CA2083525A1 - Apparatus and method for intravascular cavitation or delivery of low frequency mechanical energy - Google Patents

Abstract

ABSTRACT

An apparatus and method for recanalization of a blood vessel obstruction by application of low frequency mechanical energy to a vessel site or by creation of cavitation at the vessel site. The system includes a catheter assembly having a wire located within and extending through a wire support tube and adapted to move axially therewith. A driving apparatus positioned at a proximal portion of the catheter assembly imparts energy to the wire to oscillate it axially. A tip is connected to a distal end of the wire and imparts low frequency mechanical energy or causes cavitation at the vessel site to recanalize it.
Further, a fluid particle removal system can be incorporated within the catheter assembly to convey pressurized fluid via the wire support tube to the tip where the fluid is redirected in a proximal direction into a second tube of the catheter assembly coaxially positioned around the wire support tube. Particulate from the vessel obstruction being recanalized becomes attached viscously in the redirected pressurized fluid and is withdrawn from the vessel site.

Description

2~83~2~

APPARATUS AND METHOD FOR
INTRAVASCULAR CAVITATION OR DBLIVERY
OF LOW FREQUENCY MECHANICAL ENERGY

BACKGROUND OF THE INVENTION
The present invention relates to a new intravascular apparatus and method that can be used as a therapy for diseases of the vascular system that are characterized by an undesired obstruction or restriction of a vascular segment, or that can be used in con~unction with other intravascular therapeutic or diagnostic apparatuses or methods. More particularly, the present invention relates to a new intravascular apparatus and method for recanalization of an obstructed vessel or for removal and/or reduction of undeslred material that obstructs or occludes a vessel by application of low frequency mechanical energy to a vessel site or by creation of cavitation at the vessel site.
Obstructive arterial disease continues to be serious health problem in our society today.
Obstructive arterial disease can occur-in coronary or peripheral arteries. This disease i9 the result of the deposit and accretion of fatty substances on the interior surface of the walls of the arteries. The build up of such deposits results in a narrowing of the diameter of the artery which restricts the blood flow . .

-., .
: . ' , . ` ' ''' ~
- ' .

2083~

through the artery. Thi~ condition wherein the artery is narrowed i~ known generally a~ stenosis.
Various therapies have been considered and developed for the treatment of obstructive vascular disease. One treatment is coronary artery bypass graft surgery. Bypass surgery, however, has the disadvantage that it i8 extremely invasive and traumatic to the patient. Accordingly, less inva~ive and less traumatic alternative therapies to bypass surgery are desired.
Several less invasive alternatives to bypass surgery have been developed that rely upon intravascular catheterlzation. Intravascular catheterization therapies involve the positioning of an elongate tubular catheter incorporating a therapeutic implement via a blood vessel to the site of the vascular obstruction to treat it. One such intravascular procedure is angioplasty. Angioplasty iq a procedure in which an inflatable balloon is positioned on the inside of the artery at the site of the lesion and expanded in order to compress the materials at the lesion and thus open the restricted area in the artery. In this procedure, a balloon is attached to the distal end of a ~mall dlameter flexible catheter which includes a means for lnflating the balloon from the proximal end of the catheter. The catheter i~ maneuvered through the patient's vessels to the site of the lesion with the balloon in uninflated form. When the uninflated balloon ie properly positioned at the lesion, the balloon is then inflated to dilate the restricted area.
Although angioplasty is presently the most well developed and widely used intravascular therapeutic procedure, other intravascular 208352~

catheterization therapie~, ~uch a~ atherectomy and la~er irradiation, have al~o been considered and developed to a ~tage of at least limited ~ucce~s.
Other therapeutic approaches in addition to the~e have also been con~idered and/or developed. Although exi~ting therapies have proven to provide generally good result~ in many ca~e~ of ob~tructive va~cular dlsease, no one therapy ha~ yet proven to be succe~sful for all ca~es of va~cular disea~e. Moreover, with existing therapies for ob~tructive va~cular di~ea~e, regtenoci9 i5 ob~erved in a ~ignificant percentage of ca~es following the intravascular procedure.
Accordingly, there ctill ic a need for a new therapy for treatment of obstructive vascular diseases.
One therapeutic approach that ha~ been considered for treatment of obetructive vaecular disease i~ the application of ultraeonic mechanical energy to the vascular ob~truction. Ultra~ound apparatu~e6 and method~ have been utilized for the removal or break up of undesired material in body location~ other than blood veeeele. For example, ultraconic therapie~ have been utilized to remove kidney or gall etone~ and have been applied a~ well to other undesired materiale, euch a~ malignancies. In thoce therapeutic method~ in which ultra~ound ha~ been successfully used to remove unwanted material fram the body, the material to be removed ha~ been in a location of the body at which a euitable methodology for delivery of the ultraeonic energy to the material could be utilized. One example of cuch an apparatu~ i~ a cell disrupter. A cell dl~rupter has a mechanical horn that i8 vibrated at a high natural frequency (e.g. 10 -30 kilohertz) to direct ultraeonic energy to undecired , , ~ . . .

' . ' `

2083~25 cell groups or chemical groups in the body through a medium ~uch a~ a biological fluid or chemical eolution.
The delivery of ultrasonic energy to the undesired cell or chemical group operates to break up the group.
Ultrasonic therapeutic method~ have been con~idered for the break up and/or removal of undesired material or occlusions in blood vessels of the body.
The use of ultrasonic energy to break up undesired material in the vascular system is promiYing because of the apparent selectivity in breakdown of unde~ired obstructive material compared to surrounding healthy tiseue upon delivery of energy. Directed ultrasonic mechanical energy appears to selectively break down - undesired material in a vascular region, such as plaque or thrombu3, while causing no apparent damage to surrounding healthy vessel segmenSs. However, desplte the appeal of ultrasonic energy as a therapy for obstructive vascular diseases, it hae 80 far not been successfully used for obstructive vascular diseases.
One of the problems associated with the use of ultrasonic therapeutic techniques in the vascular system has been how to deliver the energy to blood vessel sites, especially vessel sites that are deep within the body.
At the present time, distal ves~el sites, such as the coronary arteries in which stenosis commonly occurs, are routinely acce~sed by small diameter guide wires or catheters from remote locations such as the femoral artery for diagnostic and therapeutic procedures, such as angiographies, balloon angioplasties, and atherectomies. Further, physicians and clinicians who practice in this specialty have developed familiarity and skills as well as numerous ~ u ~

accessorie~ to a~si~t in cardiovascular catheter and guide wire placement. Accordingly, it would be advantageou~ to utilize catheter~ and/or wire~ for ultra~onic energy delivery to a distal ve~sel location.
However, u~ing catheters and/or guide wires for the delivery of ultrasonic energy ha~ ceveral technical difficultie~ which have co far presented significant obstacles to the development of this therapy. Guide wire~ for u~e in pocitioning in the coronary tract may have a diameter on the order of 0.010 to O.Ola inches and a length of at least approximately 175 cm.
Catheterc and guide wires are de~igned to be flexible longitudinally in order to traverce tortuous vecsel paths. Thus, becau~e cathetere and wires are usually designed to be flexible, they are not well ~u~ted to convey mechanical energy. Accordingly, the very properties desired and necee~ary in guide wire~ or catheter~ in order to po~ition them are the same properties that have made them un~uitable for transmitting ultra~onic energy.
One previously considered approach to conveying ultra~onic energy via a wire to a distal vecsel location i8 to ~et up a harmonic wave in the wire. According to this approach, a colid wire, made of titanium for example, can be vibrated at itc natural freguency (which ic a function of itc length). A
~ignificant problem a~cociated wlth conveying ultraconic energy by ~uch a method i9 that it causes the entire wire to vibrate tranevercely as well. Thi~
tran~verse motion generates conciderable friction which result~ in undesirable attenuation along the length of the wire thereby reculting in a ~ub~tantial amount of heat in the ves~el. This iB an unde~irable re~ult that .: " ~ ' ' - , ,.
' : '-,' ' 2~83~

preclude~ operation for a sufficient period of time to be effective. Moreover, the harmonic wave set up in the wire attenuates quickly if the wire is maintained in a curved configura~ion which is typlcal for access to remote vessel locations. These drawbacks have prevented thi~ approach from achieving practical application.
Another concern associated with using ultrasonic techniques in a patient's blood vessel relates to the break up of the undesired material. The break up of undesired material~ in a person's body in other body locations, ~uch as in the kidney or gall bladder, by ultrasonic technique~ may not be of concern becau~e the presence of smaller, broken-up particles of the undesired material in such locations present little or no serious problem. However in arterial sites, the break up of material may pose problems. A~suming that ultrasonic energy could be succes~fully applied to a blood vessel obstruction, it i~ a concern that particles of the broken up occlu~ion may be carried away to another blood ves~el location and cause a restriction of blood flow there. Worse yet, particles of a broken up occlusion may become lodged in other locations causing clots. Prior method~ for applying ultrasonic techniques to blood ve~sels have not addressed capture or removal of particulate from the blood vessel following treatment.
Therefore, it is an ob~ect of the pre~ent invention to provide an apparatu~, system and method for recanalization of an occluded or partially occluded body vessel through the u~e of delivering mechanical energy to a vessel location.

It i9 another object of the present invention to provide an apparatuq, system, and method for use with other therapeutic methods and apparatu~es and which is adapted to prcvide for recanalization of an occluded or partially occluded ve~sel at least to a degree to facilitate use of the other therapeutic method~ or apparatuces.
It i~ yet further ob~ect of the present invention to provide an apparatu~, ~y~tem, and method for delivering mechanical energy over an elongate wire to a va~cular ~ite.
It i9 still a further ob~ect of the present invention to provide an apparatu~, ~y~tem, and method for delivering mechanical energy over an elongate wire lS to a vascular site without the build up or generation of heat due to transverse wire motion.
It i~ yet still a further ob~ect of the present lnvention to provide an apparatu~, ~ystem, and method for removal of undeeired materlal from a arterial ~ite ln con~unction with the recanalization of the artery by the delivery of mechanlcal energy to the artery ~ite.

SUMMARY OF THE INVENTION
According to a first aspect of the invention, there i~ provided an apparatus and method for recanalizatlon of a blood vessel obstruction by application of low frequency mechanical energy to a veecel cite or by creation of cavitation at the vee~el slte. The eyctem includes a catheter as~embly having a wire located within and extending through a wire support tube and adapted to move axially and/or longitudinally therewith. A driving apparatus .: -.. . . ,, . ~ , - .. - : ~ -- 8 - 2~8352~

positioned at a proximal portion of the catheter assembly imparts energy to the wire to oscillate it axially. A tip i9 connected to a distal end of the wire and imparts low frequency mechanical energy or causes cavitation at the vessel site to recanalize it.
The catheter as~embly also include~ a second tube located around the wire suppor~ tube to damp transverse movement of the catheter assembly during oscillation of the tip.
According to a further aspect of the invention, a fluid particle transmisslon system i8 incorporated within the catheter assembly to convey pressurized fluid via the wire aupport tube to the tip where the fluid is redirected in a proximal direction into the second tube of the catheter assembly.
Particulate from the vessel obstruction being recanalized becomes attached viscously in the redirected pres~urized fluid and is withdrawn from the vessel site.

BRIEF DESCRIPTION OF THE PIGURBS
Figure 1 is a schematic representation of a system that incorporates aspect~ of a first embodiment of the precent invention.
Figure 2 is a sectional view of a proximal portion of the catheter assembly ~hown in Figure 1.
Flgure 3 i8 a sectional view of a distal portion of the catheter assembly and dietal tip shown in Figure 1.
Figure 4a is a sectional view of an intermediate portion of the catheter assembly chown ln Figure 1.

~, .

2û~3~2~
g Figure 4b i3 an alternative embodiment of the intermediate portion of the catheter as~embly ~hown in Figure 4a.
Figure 5 i8 a cutaway view of the particle S removal sheath portion of the catheter assembly ~hown in Figure 1.
Figure 6 is a cutaway view of the proximal end of the catheter assembly shown in ~igure 1.
Figure~ 7a and 7b depict cutaway views of alternative embodiments of the proximal edge of the distal cap shown in Figure 3.
Figure 8 is a flow chart of a preferred power control syetem (driving apparatus) for the system 10 of Figure 1.
Figures 9a to 9h are circuit diagrams for the power control ~ystem of Figure 3.
Figure 10 is a axi-~ymetric cutaway view of a solenoid pole assembly (with an illustration of the flux path associated therewith) that forms part of the driving apparatu~ ~hown in Pigure 1.
Figures lla to lld illustrate the steps associated with the con~truction of the pole shown in Figure 10.
Figure 12 i~ a graph illu~trating the relationship between amplitude and frequency that establishe~ the operating thre~hold nece~ary to cause cavitation at the tip during intravascular operation.
Figures 13a and 13b are graphs illustrating alternative driving waveforms which could be generated by the driving apparatu~ of Pigure 1 for operating the system.

:

~- -208352~

Figure 14 i~ a ~ectional view of a distal portion of an exchange ~heath that may be used in conjunction with the embodiment of Figure 1.
Pigure 15 i~ a ~ectional view of an intermediate portion of the catheter a~sembly of an alternative embodiment of the present ~ystem that doe~
not incorporate fluid particle removal.
Figures 16a and 16b are cro~s ~ectional and longitudinal ~ectional views of an intermediate portion of the ~econd tube of the catheter assembly of a further alternative embodiment of the precent ~ystem that does not incorporate fluid particle removal.
Figure 17 i~ a sectional view of a distal portion of the catheter assembly of Figure 1 illustrating alternative embodiments of the profile of the end cap tip.
Figures 18a and 18b depict views of alternative embodiment~ of the dlstal cap.
Figure~ l9a to l9c depict alternative embodiment~ of the di~tal tip adapted for drug delivery.
Figure 20 i~ a croes cectional view of an intermediate portion of the catheter a~embly illustrating an alternative embodiment of the distal particle removal eheath eupport guide.
Figure 21 is a cross sectional view of the proximal portion of the catheter as~embly depicting an alternative embodiment of the ma~ pring ~yctem.
Figure 22 i~ a cro~ sectional view of a distal portion of an alternative embodiment of the catheter a~sembly incorporating an lnflatable dilation balloon.

2083~2~

Figure 23 ia a cross sectional view of an di~tal portion of an alternative embodiment of the second tube portion of the catheter ac~embly incorporating an expanding tip to facilitate exchange of intrava~cular device~.
Figures 24a and 24b are cross sectional view~
depicting alternative embodiment~ of the core wire.

DETAILED DESCRIPTION OF THE

PRES~NIh~ PREFER~p EMBODIM~

In the detailed description that follows, a fir~t preferred embodiment will be deccribed that utilizec intrava~cular energy delivery in con~unction with a fluld particle removal sy~tem. Next, another preferred embodiment will be described that utilize~

intravaccular mechanical energy delivery without a fluid particle removal system. m en, further alternatlve embodiments of the ~ystem(~) and/or ~ystem componentc will be described.

I. THE SYSTEM WITH PLUID PARTICLB R~MOVAh A. THE SYSTEM IN GBNERA~

Referring to Figure 1, there i9 illu~trated a ~chematic reprecentation of a eystem 10 according to a firct embodiment of the pre~ent lnvention. The cystem 10 provide~ for the intravascular delivery of mechanical energy as a therapy by itcelf or in con~unction with other intra~a~cular therapeutic or diagnostic method~ and sy~tem~. The guantity of energy delivered with thic embodiment is preferably selectable by the u~er within a range extending from a quantity of energy sufficient to cause cavitation at a vescel cite down to a quantity of energy lesc than the amount .:

.

- - 208352~

required to produce cavitation ~e.g. a lower frequency and/or amplitude). The system 10 include~ a catheter a~embly 14 with an energy delivery tip 16 and a driving apparatus 18. In thi~ embodiment, the sy3tem 10 al~o lnclude~ a fluid particle removal system 20 including a pre~urized fluid source 22 and a fluid discharge outlet 24.
In a present embodiment, the catheter a~sembly 14 has a working length of approximately 53.15 inche~ (135 cm) measured from the distal portion of a proximally-provided manifold to the distal tip 16. In a preferred embodiment for use in the peripheral va~culature, the catheter assembly 14 will have a di~tal external profile in a range between 0.060 and 0.01~ inches. In a preferred embodiment for use in the coronary vasculature, the catheter assembly 14 will have a distal external profile in a range between 0.04 and 0.010 inches. The following preferred embodiment will be described in terms of a catheter assembly 14 suitable for use in the peripheral vasculature. A
catheter assembly for use in the coronary vasculature may be provided making corresponding ad~ustments to the dimensions provided in accordance with the ranges noted above.

B. THE CATHETER ASSEMBLY
1. In General The catheter assembly 14 has a distal portion 26 sized and adapted to be positioned intravascularly to a site ln a patient's blood vessel at which treatment by application of low ~requency mechanical energy or by creation of cavitation is to take place.
The energy delivery tip 16 is located at a distal end . ~ ~

2083~2~

2~ of the catheter assembly distal portion 26. The vessel treatment site may be a location at which an ob~truction by undesired material has been determined to be present. The presence and location of the undesired material may be diagnosed by angiographic methods (e.g. dye~) well known in the art. The undesired material may include plaque, ~tenosis, organized fibrotic, collagen, or atherosclerotic materials.
A proximal portion 30 of the catheter assembly 14 is adapted to be positioned outside of the body of the patient. The driving apparatus 18 i8 associated with the proximal portion 30 of the catheter assembly 14 and is adapted to activate the delivery of low frequency mechanical energy from the tip 16 or for creation of cavitation at the tip 16. The catheter assembly 14 i~ compo~ed of a core wire 32 extending therethrough and connected to the tip 16 for the transmis~ion of the energy from the proximal end of the catheter aseembly to the distal end. The catheter assembly 14 is also compo~ed of a first tube 34 (al~o referred to herein a~ the wire ~upport tube or the supply tube) and a ~econd tube 36 ~al~o referred to herein as the particle removal sheath or the damping sheath) which are coaxially diepo~ed about the core wire 32. The core wire 32 is adapted to move in o~cillation axially within the fir~t tube 34, as described in further detail below. The second tube 36 i~ adapted to reduce or prevent tran~verse oscillation of the catheter assembly during oscillation of the core wlre axially as well as provide additional functions as described further below.

~083~2~

2. Sup~ort tube in general The support tube 34 i~ adapted to ~upport the core wire 32, maintain a pre~sure head through the catheter a~embly, and reduce fluid flow losse~ while po~sessing a sufficiently low profile and flexibility for intrava~cular u~e. In both the presently described embodiment that includes fluid particle removal and in the em~odiment de~cribed below without fluid particle removal, the support tube 34 functions to provide a ~upporting path through which the core wire 32 can translate axially with minimal lo~ due to transverse vibration. Accordingly, the support tube 34 provides for radial support for the axially translating core wire 32 from its proximal end to its distal connection to the tip 16. In the present embodiment with fluid particle removal, the support tube 34 also provides an additional function. In the pre~ent embodiment, the support tube 34 al~o provide~ an annular pa~sage between the core wire 32 and the inner surface of the support tube 34 through which the pressurlzed fluid can flow distally to the tip.
The annular clearance of the eupply tube 34 around the core wire 32 also determines the amount of flow lo~ through the system. The overall di~tal profile of the catheter a~sembly (including the ~upply tube) i9 con~trained distally (i.e. corresponding approximately to the di~tal 35 cm) in order to provide intravascular acce~. In order to reduce flow losse~
up to this dictal location, the annular clearance between the core wire and the cupply tube is increased to its maximum allowable ~ize to minimize flow lo~see through the proximal section of the catheter as~embly while maintaining an overall low profile and support 2083~2~

for the core wire. The maximum proximal profile of the catheter a~sembly allow~ for an annular clearance outside of the catheter assembly for flushing of contrast fluid during a typical procedure when S in~talled in a 7 or 8 French guide catheter.

3. SuDport tube proximal Dortion In the first embodiment, associated with the proximal portion 30 of the catheter assembly 14 i9 a manifold aesembly 40. The manifold assembly 40 includes a first port 42 and a second port 44. The fluid source 22 i~ adapted to pro~ide fluid 41 (e.g.
saline) under pressure to the first port 42 of the manifold assembly 40 via a supply line 43. The first tube 34 is connected in a proximal portion thereof to the first port 42. The first tube 34 extends distally from the first port 42 to the distal portion 26 of the catheter as~embly 14 and proximally from the first port 42 to a proximal end 46 of the firct tube 34.
Hydraulic pre~sure i~ transmitted through the catheter assembly 14 via a first tube lumen 48 of the first tube 34 from the fluid source 22 to a distal end 50 of the first tube 34 and then to the tip 16.
Referring to ~lgure 2, in a preeent embodiment, the first port 42 is compri~ed of a T-block 52 placed in-line in the first tube 34 of the catheter as~em~ly 14. The T-block 52 may be a commercially available unit purchased ~rom Hlgh Pressure Bquipment Company, of 8rie, PA. U~ed in con~unction with the T-block 52 are nuts and gland~ 54 to form a fluid tight connection to the fluid ~upply line 43 from the fluld ~ource 22. The T-block 52 connect~ the fluld ~upply 22 to a first portion 5B of the ~upply tube 34 that 2~83~2~

extends proximally from the T-block and which i8 located within a ~pring bushing 60 and to a second portion 62 of the aupply tube 34 that extend~ di~tally from the T-block and which i~ located within a wire support bushing 64. It i~ preferable that the T-block be readily connectable and disconnectable from the pressurized supply line 43 to facilitate use. In further embodiments, the T-block may be manufactured as a custom unit.
At the T-block, fluid preasure is directed both proximally and distally in the supply tube 34. In this embodiment, the fluid 41 moves di~tally in the lumen 48 of the supply tube 34 to the distal tip 16.
In this embodiment, the fluid 41 enters the sy~tem under pressure (e.g. 1000 p8i or le~s), as further explained below.

4. SuDport tube d1~aL ~oX~ion Referring to ~igure 3, there is depicted the distal end 50 of the supply tube 34 and the distal tip 16. The pressurized fluid 41 is directed from a support tube distal opening 72 located at the distal end 50 of the supply tube 34 to the tip 16. The tip 16 includes a tip channel 74 located internally thereto and open proximally to receive the pres~urized fluid 41 and redirect it ln a proximal direction.

5. Support tuk~ ermediate DortiQ~
In a preferred embodiment, the support tube 34 i8 comprised of sections along its length having different internal and external diameters. The ~upport tube 34 is provided with sections of different internal and external diameters to allow the flowing fluid - ' -208352~

medium 41 to retain more of its inherent pressure head by reducing flow losse~ due to resistance. The Darcy-Weisbach equation demon~trates that as annular clearance~ are reduced, head 1088 is increased because the annular clearance is reduced and the fluid veloc~ty is increased through the section to maintain flowrate.
Thus the diameter of the support tube 34 i~ determined for operation at a given driving pressure.
Referring to Pigure 4a, a step down in the diameter of the supply tube 34 occurs at a location 76 approximately 100 cm distally from the distal end of the second port 44 of the catheter assembly. In the pre~ent embodiment, this step down is accomplished by forming the support tube of separate sections 78 and 80 fitted into each other and lap soldered together. In a preferred embodlment with an operating pressure of 1000 psi, the inner diameter of the support tube proximal section 78 18 0.026 inches. The inner diameter of the support tube dl~tal section ~0 is 0.013 inches. The outer diameter the support tube proximal section 78 i~
a constant 0.036 inche3. In the distal section 80 of the wire support tube 34, the outer diameter ~aries.
The distal wire support tube outer diameter is 0.025 inches for the first 3.9 inches distally from location 76. Then, the outer diameter of the distal support tube section 80 tapers linearly for 2 inches down to a finished outer diameter of 0.017 inches. In this most dietal portion of the wire ~upport tube 34, the wire support tube wall is 0.002 inches thick to provide a deslred degree of flexibility and supply pressure. In order to accommodate the differences in diameter between the inner diameter of the proximal section 78 and the outer diameter of the distal support tube .

section 80, a bushing 81 is positioned between the di~tal and proximal section~ at the connection location 76.
In one embodiment, the proximal and distal ~ections 78 and 80 of the wire ~upport tube are formed of separate piece~ ~oldered together, however alternatively, a necked tubing would be a preferred.
The preferred necked configuration i~ illu~rated in Figure 4b. In Figure 4b, the ~upport tube 34 would be formed of a single piece of tubing having dimeneions corresponding to those of the proximal ~ection 78'and processed, for example by necking, to form the di~tal ~ection 80' dictally of the tapering location 76'. A
necked configuration would provide a smoother flow path tran6ition through the catheter a~embly thereby reducing flow lo~e~.
The supply tube dimension~ are selected in part to provide a ~pecific preferred annular clearance between the inner wall of the supply tube 34 and the core wire 32. The annular clearance between the core wire 32 and the firct tube 34 i~ ~elected ln part to optimize effective performance through various bends that the catheter assembly 14 will undergo during intrava~cular use. In a pre~ent embodiment, the annular clearance ic 0.0025 inches in a distal portion and 0.005 ln a proximal portion. Alternative clearance~ may be appropriate.
In the precent embodiment, the ~upport tube 34 i9 fabricated of 304 stainle~c steel although other materials including non-metals having cimilar propertie~ may al~o be uced. Alternatlvely, the ~upport tube could be fabricated using fiber compo~ite technology, i.e. the tube could be formed of compo~ite ' ' : ' ' ' .

20~3~2~

filaments captured in a resin or polymer. Such a construction could increase device pushability, hoop strength, and support to the core wire.
Referring again tO Figures 3 and 4a, in the present embodiment, particle removal ports 82 and 84 are provided in both sections 78 and 80, respectively, of the wire support tube 34. These ports 82 and 84 route the fluid 41 back into the particle removal sheath 36. This redirection by the particle removal port~ 82 and 84 allows the kinetic energy of the fluid 41 to become the driving pressure for pushing the fluid and any particulate broken away from the vessel obstruction back to the manifold exhaust port 44. In a preferred embodiment, two sets of ports are incorporated to provide a two stage drawing capability.
Primary particle removal is provided by the proximal ports 82 and secondary routing or particle removal initiation is provided by the distal ports 84. In a present embodiment, the proxlmal port~ 8~ each have a diameter of 0.010 l/- 0.005 inche~ and the distal ports 84 each have a diameter of 0.003 ~/- 0.002 lnches. In a present embodiment, there are two dl~tal port~ and two proximal ports, however, fewer or more port~ along the shaft length may be provided and the port ~lze can be modifled to ad~ust flow balance and characterlstics.
As a way of improvlng the preesure balance ln the arterlal envlronment during operatlon and maintaining particle removal flow, distal fluid disperslon orifices 85 may be provlded. The dispersion oriflces ~5 would be located proxlmal to the proxlmal end of the distal tip 16 at which the redirected fluld exits the distal tip. The dlsperslon orifices 85 would be formed to direct fluid normal or slightly proximal to the distal tip axi~. The orifices 85 would be located around the periphery of the supply tube 34.
The orifice or port ~ize i9 determined so that a flow balance would be maintained in the artery, thereby preventing collapse of the artery due to a pres~ure vacuum. The dispersion orifice~ 85 port~ are preferably ~ituated around the periphery of the supply tube 34 90 that the proximally directed fluid flow out of the distal tip 16 would be disrupted in aelect locations corresponding to the location~ of the dispersion orifices, but would remain uninterrupted in the locations between ad~acent disper~ion orifice~ in order to maintain the particle removal flow path.

6. Parti~le re~oval (damDing) ~heath Referring to Pigure~ 1 - 4, the eecond port 44 of the manifold a~embly 40 provide~ the outlet for the discharge of fluid effluent and any particulate attached viccouely therein. The ~econd tube 36 (al~o referred to a~ the particle removal or damping ~heath) i9 connected at a proximal end 86 thereof to the second port 44. The particle removal oheath 36 exteDd~
distally from the eecond port 44 to the di~tal portion 26 of the catheter a~embly 14. The fluid 41 i8 withdrawn from the catheter a~embly 14 via a particle removal cheath lumen 88 of the particle removal ~heath 36. The particle removal ~heath 36 extend~ from the second port 44 to a distal particle removal sheath opening 90 at the di~tal end 26 of the catheter a~sembly 14. The particle removal ~heath di~tal opening 90 ic located ad~acent to the channel 74 of the tip 16, and ~peciflcally the particle removal ~heath distal opening 90 i9 located ~u~t immediately proxinal 2083~25 of the tip channel 74. The particle removal sheath 36 functions to receive and withdraw fluid 41 and any material attached viscou~ly therein from the area at the particle removal sheath di~tal opening 90. In particular, the particle removal sheath 36 withdraws the fluid 41 ~upplied via the supply tube 34 that i~
directed at and redirected by the tip 16. In addition, the particle removal sheath 36 functions to draw particles or material, if any, that may become broken off from the undesired material of the vessel obstruction being treated by the application of energy from the distal tip to the vessel site. It i9 expected that some, if not most, of euch broken off particles or material in a certain size range would tend to be attached viscously in the fluid 41 drawn via the particle removal sheath distal opening 90 though the particle removal sheath 36. In a preferred embodiment, the supply tube 34 is located ln the particle removal sheath lumen 88 and is slzed to occupy only a portlon of the particle removal ~heath lumen 88, thereby providing an annular region ~ufficient to accommodate withdrawal of fluid 41 via the particle removal sheath lumen 88. Accordingly, it i8 also preferred that the particle removal sheath dlstal opening 90 i8 formed by the annular region 92 at the dlstal end of the partlcle removal sheath 36 between the lnslde of the particle removal sheath 36 and the out~lde of the first ~or supply) tube 34.
Referring to Figure 2, the particle removal sheath 36 terminates proxlmally at the second port 44.
The second port 24 i9 provlded by a Y-manifold 96 connected to the proximal end of the particle removal sheath 36. Inside the Y-manifold 96, the particle 2~83~2~

removal sheath 36 terminate~ distal to an O-ring compression seal 98 on the wire support tube 34. The O-ring 98 i8 retained in the Y-manifold 96 by a compre~sion nut 100. The second port 44 exhausts the withdrawn effluent to a collection pump (not shown) which provides po~itive pressure or vacuum.
Referring to Figure 5, the particle removal sheath 36 is provided with dimensions to provide for fluid dynamics ~imilar to those of the wire support tube 34 but with substantially lower flow losses through its length. In a present embodiment, the particle removal sheath 36 is formed of a first section 102 connected to the Y-manifold 96. The particle removal sheath 36 may be connected to the Y-manifold 96 by a urethane bond. The particle removal sheath first section 102 is 39.8 inches ~101 cm) long and has an inner diameter of 0.042 and an outer diameter of 0.052 inches. The particle removal sheath first section 102 connects to an particle removal sheath second section 104. In this embodiment, a ~econd ~ectlon 104 fits into the first section 102 and extends 13.4 inches (33.9 cm) distally therefrom. The first and second sections 102 and 104 may be connected by a urethane bond. (Instead of forming the particle removal sheath 36 of separate section~, it can al~o be formed of one piece of tubing and nec~ed or otherwise processed to produce the desired change in profile in a manner similar to that described above with respect to the ~upply tube and depicted in ~igure 4b). The overall length of the particle removal eheath 36 from the distal end of the Y-manifold 96 to the distal end thereof ie 53.1 inches. In a preferred embodiment, the particle removal sheath is formed of a single piece of - 23 - 208~2~

tubing necked to provide the first and second portions 102' and 104' as shown in ~igure 4b. The proximal portion 102~ ha~ a length of 101 cm with an outer diameter of 0.052 lnches and an inner diameter of 0.042 ~nche~. The particle removal sheath second section 104' ha~ a length of 34 cm with an outer diameter of 0.03s inche~ and an i~ner diameter of 0.029 inches. As with the supply tube, described above, the second tube may be formed of more than one piece of material and connected together to provide the change in inner and outer diameters, as described above. Such a construction is illustrated in ~igures 4a and 5. If separate pièces are used, the pieces could be connected together by suitable means ~uch as a urethane bond.
Additional lengths of tubing may be provided for the purposed of forming an overlapping bond between such separate pieces. An additional length may be provided to connect the proximal end of the second tube into the Y-manifold. In addition, it may be de~lred to provide the second tube with additional changes in profile to contribute the fluid characteri~tics, damping, etc.
The distal and proximal sections of the partlcle removal ~heath 36 provide e~sentially similar functions. Like the eupply tube 34, the inner and outer diameters of the particle removal sheath 36 are sized based on fluid dynamic analysi~ for minimizing pressure drop through each section or portion of the partlcle removal sheath. The particle removal sheath 36 is also provlded with sufficient annular stlffness to prevent collapeing during particle removal flow. A
necklng process may be used in the construction of the particle removal sheath second section 104 to provide for reduction in diameter and wall thicknesses. In a .

2083~2~

preferred embodiment, the outer diameter of the distal portion 104 of the particle removal sheath is equal to or lec~ than the outer diameter of the oscillating di~tal tip 16 to prevent catching of the distal end 90 of the particle removal ~heath 36 on lesion material a~
the tip 16 advances therethrough.
The particle removal cheath 36, in a present embodiment, i~ constructed from a high density polyethylene (HDPE). HDPE po~es~es propertie~
concidered to be desirable for use a~ a material for the particle removal sheath. These propertie~ include relatively high stiffnecs and low coefficient of friction. Other materials for the damping sheath may be used including other pla~tic~ or even metals, ~uch as sta~nless ~teel or a combination of metal(~) and non-metal~, e.g. a composite ~uch a~ a bralded configuratlon. Alternatively, the damplng sheath could be fabricated ucing fiber composite technology, i.e.
the tube could be formed of compoclte fllament~
captured in a resin or polymer. Such a construction could increace device pu~hability, hoop ~trength, and support.
It i9 preferred that the particle removal ~heath 36 be maintained concentrically disposed about the ~upply tube 34. Accordingly, a ~heath guide 112 may be u~led. The sheath guide 112 retalne the concentricity of the particle removal cheath 36 around the dictal ~upply tube 34. Thic ha~ the advantage of preventing any side cpray or di$fuclon of the operating fluid 41 when it ic redirected proximally into the distal opening 92 due to the particle removal ~heath 36 becoming eccentric. The ~heath guide 112 i9 fabricated from radlally expanding leaf ~pring~ which provide a .
.~ -: , .. . . .
- - - -. , ~

2~$3~2~

radial force in an axis-symmetric fas~,ion to produce the proper centering effect.
In addition, in a preferred embodiment, a deflector 114 is provided to additionally support redirection of the fluid leaving the proximal exhaust port 82. The deflector 114 reduces or prevents dispersal when the fluid impact~ the inner wall of the particle removal sheath 36. In a present embodiment, the deflector is formed of a tapered piece of stainless steel to reduce flow losses therearound.
In addition to providing an annular passageway for the return effluent particle removal flow, the particle removal sheath or second tube 36 al~o acts as a damping sheath to reduce or prevent the generation of transverse waves when the core wire 32 is driven in translation. The ~econd tube 36 provides this damping function by providing a frequency dependent ~tiffne~ to the catheter assembly. Based on the damping coefficient of the material, the force exerted by the particle removal sheath 36 on the core wire 32 i~ increa~ed a~ freguency goes up. The reaction force follow~ the following relation~hip:

Damping Force - Damping Coefficlent ~ Velocity The velocity component in the above equation i9 determined by the operating frequency of the sy~tem.
A~ the velocity is increa~ed, the restraining force is increased linearly. The velocity i~ the relative velocity between the ~heath 36 and the wire ~upport ~ube 34.
In this embodiment that incorporates fluid particle removal, the return effluent occupying the - 26 - 2083~2~

region between the support tube 34 and the particle removal sheath ~erve~ the function of a damping layer.
In other embodiment~ without fluid particle removal, alternative material~ may be used to provide for the damping function, as described further below.

7. Core wire generally Referring again to ~igures 1 to 4, the catheter assembly 14 also includes the core wire 32.
extending therethrough. The core wire 32 i9 connected at its di~tal end to the tip 16 and extends from the tip 16 proximally through the first tube lumen 48 of the catheter assembly 14 to the proximal end 30 thereof~ In thi~ preferred embodiment, the core wire 32 is ~ized to occupy only a portion of the first tube lumen 48 thereby allowing an annular region ~ufficient to accommodate delivery of fluid 41 via the first tube lumen 48 in the annular region. The supply tube distal opening 72 i6 formed by the annular region at the distal end 50 of the first tube lumen 43 between the in~ide of the fir~t tube lumen 48 and the core wire 32.
The core wire 32 provides the function of transmittlng phy~ical displacement from the proximal end 30 of the catheter assembly 14 to the dietal portion 26 and cpecifically to the tip 16. The transmittance may be accomplished by tran~lation and/or elongation of the core wire 32. In a preferred embodiment, the transmittance i~ accomplished primarily by translation and ~econdarily by elongation. In order to perform thi~ function, the core wire 32 i~
preferably of a biocompatible materlal posse~slng a high tensile strength and a high endurance limit. In a pre~ent embodiment, high tensile strength ~tainle~s 208352~
- 27 ^

steel 304 wire i~ used. In a present embodiment, the wire u~ed pos~esses a tensile ~trength of approximately 300-400 kp~i. In a pre~ent embodiment, a commercially available wire i~ used having a trade name of HYTEN
stainless steel wire and produced by Fort Wayne Metal Products, Fort Wayne, Indiana. The preferred diameter of the core wire is approximately 0.008 inches, although a wire in the range between 0.005 and 0.010 inches i~ also considered acceptable. Alternate material~ having similar properties may be used for construction of the core wire such as titanium or tltanium alloy.
In order to increase axial stiffness (pushability) of the core wlre, the core wire may be provided with a larger profile in its proximal portion and a smaller profile in it~ distal portion. ~his may be accomplished by providing a core wire with a tapered profile or a profile that i~ ~tepped or a combination thereof. The core wire preferably has a small profile distally for increased flexibillty in the di~tal section. Since the catheter a~sembly is intended for both peripheral and coronary applications, distal flexibility i~ important. In a present embodiment, the profile of the proximal portion of the core wire is enhanced by the addition of a stainless eteel hypotube positioned on the proximal portion of the core wire.
The stainless steel hypotube extends over the proximal 39.4 inches of the core wire. The ~tainles~ ~teel hypotube has an outer diameter of 0.015 inches and an inner diameter ~lightly larger than the diameter of the core wire 32 (i.e. O.OOB inche~). The core wire and the hypotube are soldered together 80 that the effective outer diameter of the core wire in the -- -- -- -- -- . .

20B3~2~

proximal portion (extending over the proximal 42 inche~) i8 0.~15 inches. The core wire diameter distal of the hypotube i~ the diameter of the core wire only, i.e. 0.008 inche~. Alternatively, in~tead of being formed of separated piece~, the core wire may be formed of a Qingle piece of wire that i9 necked down, ground, or otherwise proce~sed to reduce the diameter thereof in a distal portion. In a yet further embodiment, ctainless ~teel or high tensile strength composite fiber coils may be incorpcrated to the core wire to improve its pushability while retaining flexibility.
In a preferred embodiment, the core wire i9 coated with a Teflon coating to reduce friction between the wire cupport tube 34 and the core wire 32. The Teflon coating alco contributes to damping of the core wire during oscillation. Other coatings providing low frlction may be substituted or uced.
In further embodiments, mean~ may be incorporated into the core wire or in the construction thereof, to enhance the resiliency of the core wire.
For example, the core wire can be procecced with a ctre~s relieving heat treatment for thi~ purpose.

8. Core wire and catheter accembly ~roximallY
Referring to Pigure 6, there ic depicted a most proximal portion 120 of the catheter assembly 14 including the proximal end 46 of the cupply tube 34.
The driving apparatu~ 18 (as shown in Pigure 1) impartc movement to the core wire 32 by meanc of generatlng an alternating magnetic field that operatec on a masc 122 connected to a proximal end 124 of the core wire 32.
The proximal end 46 of the supply tube 34 of the .' ' . ~ -- . . - ~ , ' ' ,:
';~ : ' '.' . .

2V83~25 catheter a~embly 14 includes a pressure vessel hou~ing 126 having therein a cylindrically shaped hou~ing chamber 128. The mass 122 is located in the chamber 128. A spring 130 i8 adapted to cooperate with the mass 122 and the core wire 32 to form a mass-spring a~embly 132, as explained in more detail below. The spring 130 i~ also located in the housing chamber 128.
The chamber 128 is sized to accommodate the axial o~cillation of the mas~ 122 therein. In this embodiment, the chamber 128 is approximately 1.5 inches in length. The driving apparatu~ 18 generates a magnetic fleld through the hou~ing 126 that operates on the ma~s-~pring a~embly 132.
The housing 126 include~ an outer sleeve portion 134 and an outer ~leeve bushing portion 136.
The outer ~leeve portion 134 provide~ a bearing ~urface for the magnetic mass 122, isolation between the magnetic ma~ 122 and the magnetic poles of the driving apparatus 18, and field coupling of the ma~
(saturation cwitch), as explained below. The in~ide diameter of the outer ~leeve portion 134 i~ ~ized to closely fit to the dimen~ion~ of the mass 122. In the present embodiment, the internal diameter of the sleeve portion 134 ie 0.210 lnche~ and the external diameter of the mass 122 ie 0.200 inche~. Thu~, in the present embodiment, the radial clearance between the sleeve portion 134 and the ma~ 122 i~ 0.005 inches. This clearance gap dimen~ion i~ determlned to provide for efficient tran~mi~sion of the magnetic field acro3~ the gap to the mas~ 122.
The outer ~leeve portion 134 i~ preferably fabricated from a magnetic material possessing a high permeability and ~aturation point. Tn a preferred 208352~

embodiment, a mild steel is used Alternatively, ~tainle~s ~teel 416 or other ~imilar material~ may be u~ed. The u~e of a magnetic material allows the flux path from the poles of the driving apparatu~ 18 to be es~entially shunted until the sleeve becomes saturated and the flux i8 forced through the ma~s 122. At the time of saturation, the flux i~ dumped into the mas~
causing a switch effect on the force level on the mass 122, essentially providing an almost square function forcing curve on the masc 122 which is a desirable re~ult.
The housing 126 also includes a threaded stud 138. The threaded stud 138 i~ included on an outside proximal end of the sleeve portion 134. The ctud 138 functions to provide for tuning of the catheter assembly 14. The sleeve portion 134 is positioned and received into the driving assembly 18, as explained in more detail below. Through the use of the threaded stud 138, the position of the magnetic mass relative to the driving apparatue solenoid poles can be ad~usted to provide the desired driving performance. It is preferred that the ~tud 138 be ad~usted to provide maximum displacement of the magnetic mass 122 induced by the magnetic field. Ad~ustment of the driving apparatus 18 durlng operation will be further described below.
As stated above, the housing 126 also includes the outer sleeve bushing portion 136. The outer sleeve bushing portion 136 forms the distal portion of the housing 126 and defines the distal wall of the housing chamber 128. The outer ~leeve bushing portion 136 fits into an open distal side of the outer sleeve housing portion 134 and includes a shoulder 142 - 31 - 2083~2~

that re~t~ thereupon. The ~leeve bushing portion 136 i8 cylindrically ~haped and approximately 0.475 inche~
in length with the shoulder portion 142 being approximately 0.375 inche~ long. In the proximal portion of the ~leeve bushing portion 136, the out~ide diameter of i9 sized and adapted to closely fit into the outer cleeve housing portion 134. The outer sleeve bushing portion 136 aleo defines a cylindrically shaped opening therethrough to receive the spring bu~hing 60.
The outer eleeve bushing portion 136 provides annular ~pacing between the outer sleeve portion 134 and the spring bushing 60. In addition, to annular spacing, the outer spring bushing portion 136 provides for coaxial as~embly of the outer sleeve portion 134 and the spring buQhing 60. In a preferred embodiment, the sleeve bushing portion 136 i~ fabricated from 302 stainle~ cteel and is attached to the outer cleeve portion 134 by means of ~oldering. Alternative materials and alternative means of connection may be suitable.
As also mentioned above, the spring bushing 60 ic mounted in the outer sleeve bushing portion 136.
In a present embodiment, the ~pring bushing 60 is cylindrically chaped and approximately 3 inche~ long and has an outside diameter of approximately 0.125 inches. The spring bushing 60 defines a cylindrically ~haped opening therethrough to receive the proximal portion of the first (or supply) tube 34. A proximal end 144 of the ~pring bushing 60 providec a mounting ~urface for a distal end of the ~pring 130. The ~pring bushing 60 also provides support to the proximal portion of the cupply tube 34 that is received in the opening therein. In a preferred embodiment, the spring 208352~

bushing 60 is fabricated from 302 8tainle8B steel.
Alternatively, other similar materials may be used. In a present embodiment, the spring bushing 60 is soldered to the outer sleeve bushing 136 and the proximal portion of the supply tube 34.
As mentioned above, the mass 122 and the spring 130 are de~igned to operate toge~her as the mas~-spring assembly 132 in conjunction with the driving apparatus 18 to impart the desired oscillation to the wire 32. Therefore, the spring-mass assembly 132 provides for both magnetic circuit coupling of force inducement from the driving apparatus 18 and dynamlc inertia for conversion of the spring~s potential energy to kinetic energy. The mass 122 is formed of a cylindrically shaped magnetic metal. In a present embodiment, the mass 122 is made of mild steel.
Thic material possesses both desired properties of high magnetic permeability and a high magnetic ~aturation point material. The mass 122 has a cylindrically 2 0 8haped rece88 14 6 located therein and oriented in a distal direction to receive the proximal portion of the spring 130. The mass 122 hae an outside diameter of 0.200 inches and an internal blind diameter of 0.180 inches. In additlon to the recese 146, the mass 122 includes a 0.025 inch center hole for core wire attachment and four peripheral holes ~not ~hown) coaxial therethrough. These latter holes function to improve fluid dynamic flow (whether air or water) around the mass 122.
The spring 130 is connected to the mass 122 inside of the housing 126. ~ e spring 130 provides energy storage for the ~ystem 10. For example, in one mode of operation of the driving apparatu~ 18, the ... . .

. . ~

: . -.. . . . .

2083~2~

magnetic field generated by the driving apparatus 18 move~ the ma~ 122 proximally. Movement of the mas~
122 proximally continue~ unit the dynamic and ~tatic forces on the ma~s 122 are off~et by the ~pring'c reaction force due to it~ attachment to the ma89 122 and the ~pring buehing 60 (i.e. the "reference point"
of the system). In a present embodiment, a "music n wire (high tensile ~trength eteel) i~ used for the ~pring. The wound spring hae an outside diameter of 0.180 inche~ overall. The spring 130 is preferably fabricated from a material havlng magnetic properties to contribute to the forcing function applied by the driving apparatu~ 18 to the magnetic ma~. In a present embodiment, the ~pring 130 le composed of wlre having a dlameter of 0.032 lnche~. In a pre~ent embodiment, the epring 130 ic eoldered to both the mass 122 and the cpring buehing 60. As mentioned above, the ma~s 122 includes the cylindrically ~haped receee 146 located therein and oriented in a dl~tal direction to receive the proximal portion of the ~prlng 130. When the spring 130 i9 attached to the magnetic mase 122, the mas~ recess 146 1~ preferably partlally fllled wlth colder ~o that some of the proxlmal ~prlng c0118 received in the mac~ recee~ 146 are fixed, i.e. not active. In a preferred embodiment, four epring coils between the mass 122 and the ~prlng bu~hlng 60 are allowed to remain actlve, that i~, allowed to move during macs o~cillation.

9- ~ia~al tip Referri.ng agaln to ~igure 3, connected to the distal end 26 of the catheter a~embly 14 1~ the distal tip 16. Specifically, the di~tal tip 16 i~ connected 2083~2~

to the di~tal end of the core wire 32. The di~tal tip 16 includes a distal cap 150 and a di~tal bu~h~ng 152.
The cap 150 and bu~hing 152 are soldered to the core wire 32 for tran~mi~sion of the core wire mo~ement.
The end tip 16 ha~ a di~tal ~urface 154 which may po~3e~se~ a ~pherical profile, or an other than spherical profile as discussed below.
The end cap 150 extends proximally from the distal bu~hing 152. The end cap 150 ha~ an inner diameter large enough ~o accommodate the distal portion and end 50 of the first tube 34 as well as to provide an annular region between the fir~t tube 34 and an inside surface of the end cap 150. The end cap 150 posce~ee~ a length ~uch that a proximal end 158 of the end cap 150 is proximal of the distal end 50 of the fir~t tube 34 and distal of the openlng 90 of the particle removal cheath 36. In a preferred embodiment, the end cap 150 has an outer dlameter of 0.036 inches, an inner diameter of 0.018 lnches, and has a length of approximately 0.200 inche~. In a preferred embodlment, the proximal end 158 of the end cap 150 lc spaced from the opening 90 of the partlcle removal tube 36 by approximately 0.05 lnches durlng operation. Thls distance will change of course when the tip is oscillating axlally. Thls di~tance may also be changed to modify the flow pattern of particulate around the tip. In a preferred embodiment, the outside proximal region of the dictal cap 150 is tapered to reduce potential for catching of the proximal edge of the cap on the arterial obstructlons durlng tlp oscillatlon.
Thi~ tapering 160 may be accompli~hed through grinding or chemical etching. A taper of approximately 10 ' . ' ; .
. . ~ .
.:: : ' . . - , -2083~25 degrees i~ pre~ently used. In a preferred embodiment, the end cap 150 i~ made of 304 ~tainless Qteel.
Located in~ide the end cap 150 and extending proximally from the end cap tip 122 i~ a solder ~oint 162. The ~older joint 162 ~urrounds a most distal portion of the core wire 32 and bondc the core wire to the end cap 150. The core wire 32, a proximal end of the bushing 152 and the end cap 150 define the channel 74 that receive~ the supply of fluid 41 from the fir~t tube 34 and redirect~ it proximally. The redirected fluid 41 and viscou~ly attached material are withdrawn from the vascular site via the di~tal particle removal ~heath opening 90. In a preferred embodiment, the end cap solder joint 162 and the bushing 152 occupy approximately 0.05 inches of the end cap 150. In a preferred embodiment, the end cap ~older ~oint 162 i~ a ~ilver ~older compatible with 304 ~tainle~s ~teel and u~ed following generally accepted ~oldering practices.
Referring to Pigure~ 7a and 7b, the in~ide proximal ~urface 164 of the end cap 150 can be modified to po~sess exit flow characteri~tic~ to improve particle removal performance. The pre~ent embodiment utilizeQ a ctraight taper for the proximal inside ~urface 164. In order to further improve flow attachment, the inside curface 164 can have a reducing taper. Conver~ely, if a more diffu~e fluid flow profile i~ preferred, an inside ~urface 166 may poQ~e~s an expanding taper, a~ illustrated in Figure 7b. All the taper configurations can be fabricated into the tip u~ing conventional machining procee~ee and deburred with a chemical etch proce~.
In order to minimize flow los~e~ and mechanical wear locces, all component~ u~ed for ~ ~ - . . . . . .

- 2083~2~

hydraullc conveyance are chemically poli~hed or etched to remove burr~ and surface imperfections.

C. DRIVING E~TRONICS AN~ HARDWARE
1. Drivinq ~lectronics In General As mentioned above, the driving apparatus 18 i9 located at and a~sociated with the proximal portion 30 of the catheter acsembly 14. m e driving apparatus 18 i~ adapted to impart axial movement (i.e.
transmittance) to the core wire 32 located in the catheter a~sembly 14. According to a fir~t preferred mode of operation, the driving apparatus 18 i~
cpecifically adapted to impart a proximally directed force on the core wire 32 which causes oscillation of the core wire due to the action of the spring 130 at the proximal portion of the core wire 32. In an alternative mode of operation, the driving apparatu~ 18 can be operated to impart a proximally directed (tensioning) force on the core wire while the pressurized fluid 41 imparts a tensioning force upon the tip 16 to move it di~tally. In this alternative mode of operation, the bu~hlng receives a fluid force that cooperate~ with the proximal mase-spring assembly 132 to provide for oscillation of the core wire 32.
Referring agaln to Pigure 6, the core wire 32 i~ connected at a proximal end 124 thereof to the mass 122. The driving apparatus 18 is adapted to apply its force to the mass 122 of the core wire 32 at a frequency, thereby cau~ing the entire core wire 32, and the tip 16 connected at the di~tal end thereof, to move in o~cillation axially. m e frequency and amplitude of the core wire movement i~ selected to deliver energy to the site at the distal end of the catheter assembly 14, :
,, ', "' ' , -- ~ . . . .

2083~2~

and specifically proximate to the tip 16, for the break up and/or removal of unde~ired material.
Referring to Figure 1, the driving apparatus 18 is compri~ed of a power control system 168 connected to a driving solenoid 169. In a pre3ent embodiment, the power control system i9 comprised of a Peavy CS-800 ~tereo power amplifier, a BR Preci~ion Model No. 3011B
2 MHz function generator, a Fluke Model No. 77 multimeter, and miscellaneou~ coaxial cables to route the function generator signal to the amplifier then route the output of the amplifier to the driving ~olenoid through the multimeter for current monitoring.
The drivlng ~olenoid i8 sized to receive the proximal end of the catheter assembly 14 and specifically, the housing 126 containing the spring mass system 132.

2. ~s~ L~L~yL~4:2 - ~-In a preferred embodiment, the above mentioned components u~ed for the power control ~ystem are incorporated into a ~ingle dedicated system. Such a sy~tem i~ repre~ented by the block diagram of Figure 8. Circuit diagrams for the power control system shown in Figure 8 are ~hown in Figures 9a to 9h. The power control sy~tem includes an emergency power control circuit (Flgure 9b), a solenoid hook up circuit (Pigure 9c), a sguare wave generator circuit (Figure 9d), a foot control ~wltch circuit (Figure 9e), a high fre~uency ~witch (Figure 9f), a peak current display circuit (Flgure 9g), and a freguency display circuit (Figure 9h).

3. Solenoid pole configuration and construction - 38 - 2083~2~

The driving solenoid is comprised of a pair of solenoid poles. Referring to ~igure 10, there is depicted a solenoid pole 170 which can be used for the driving solenoid. The poles are ~ymmetrical and constructed from four U-~haped transformer core assemblies. The core assembly i~ commercially available from ~lectro-Core, Washington, Missouri, Part Number EL-1005. The cores are constructed by laminating thin magnetic ~teel layers together to produce a highly permeable core which posses a high saturation point and low eddy current losses (due to lamination construction).
Since the proximal section of the device establishe~ a magnetic circuit, all component dimensions and tolerances are optimized for overall system performance. Air gaps in the ~y~tem appear a~
resistance to the magnetic path and reduce the effectiveness of the magnetic field transfer. The processlng ~teps for construction of the pole pieces and solenold coil are represented in Figures lla to lld.
The face~ 172 of the pole piecee are tapered to channel the magnetic flux 174 through the proximal mass thereby improving magnetic coupling with the mas~
122. Tapering the pole faces 172 al~o reduces flux loeses across a gap area 176 between the pole faces 172.
The gap 176 between the pole faces i~ 0.05 lnches. Thls dlmenelon inrluences the force transferred to the ma~s 122. Increa~ing the slze of the gap 176 would reduce the force transferred to the mass 122 and thereby re~ult in a decrease of tip ; displacement; reduclng the gap 176 decreases the 2~8352~

avaiiable mass travel, again resulting in a reduction in tip di~placement.
In a preferred embodiment, the ~olenoid has a body and tuning knob and/or stop, an inner diameter of 0.25 inches to receive the housing 126, and a length of 2.00 inche~. In a precent embodiment, the driving ~olenoid requires approximately 200 watts of power at 8 amp5.

D. QPERATION
1. Poeitioning Referring again to ~igure 1, control and operation of the catheter ascembly 14 i9 effected from the proximal portion 24 located outside of the patient'e body. Operation of the syatem to treat an ob~truction at a veesel ~ite involves positioning of the di~tal portion 26 of the catheter aeeembly 14 into the patient's vaeculature. Po~itioning may be effected by meane and methode which are known to thoee having sklll in the art. For example, the catheter aesembly 14 may be positioned percutaneou~ly into the va~cular sy~tem from an acceeeible location euch ae the femoral artery. The po~itioning of the catheter as~embly can be accompli~hed conventionally through the u~e of a guide catheter which has been already prepo~itioned to the obstructed veeeel site through the uee of a guide wire.
The distal portion of the wire eupport tube 34 may be formed or bent by the physician-clinician lnto a elight curvature to allow eteering of the tip 16 according to conventional method~ known and u~ed with conventional guide wire~ for intrava~cular po~itioning.
A elight 'J' can be formed in any variety of radii and . .

208352~

location~ proximal from the end 16 provided that the bending or curve i~ at most one inch from the distal tip and that the bend radiu3 is no le~s than 0.375 inche~.
An alternate positioning method would be to implement a quick exchange introducer as de~cribed in copending application Ser. No. 07/704,828 filed May 23, 1991 the entire disclosure of which i~ incorporated herein by reference.

2. Driving apparatus oDeration Once the catheter 14 has been positioned in the va~cular sy~tem, the clinician-physician can operate the driving apparatus 18 to impart mechanical energy from the tip 16 by oscillating the core wire with the desired ~troke, frequency and power. The driving apparatus 18 is operated to impart axial movement to the proximal portion of the core wire 32.
Thus, the operating frequency of the tip 16 is determined by the operating freguency of the driving apparatu~ 18.
The operating frequency of the system is a function of the system's stiffness (proximal spring stiffnes~ ystem mass (proximal mass and core wire), and/or ~y~tem damping ~wire support tube annulus material and clearances). Of these, the most influential component defining the system operational frequency i8 the system stiffness. Accordingly, in the conctruction of the mass-spring system 132, materials are selected and processed to provide the appropriate ~tiffne~s for the frequency of operation desired. With appropriate ~election and construction of materials, the operating frequency can be established at the 2Qg3~2~

de~ired level. In the present embodiment, the operating frequency can be establi~hed any point in a range of 100 to 5000 Hz or les~.
Tip di~placement (amplitude) i8 a factor in determining a preferred operating frequency for the ~ystem. An operating frequency and tip displacement amplitude are preferably ~elected to yield a tip velocity ~uitable to recanalize the vessel obstruction by reorganizing the obstructive material or at lea~t temporarily dicplacing it.
In one preferred mode of operation, the frequency and amplitude are ~elected to cau~e cavitation at the tip. Cavitation i~ favored as a method of disrupting the cellular ~tructure of the ob~tructive material in the ves~el. Studies indicate cavitation generate~ a ti~ue dependent disruption, i.2. hard calcified le~ion~ break up readily under low power level6 while more compliant healthy arterial tissue remain intact.
Based on fluid dynamic~ theory and obcerved arterial pre~cure~ and den~itiec, the relation~hip between frequency and di~placement to initiate cavitation has been defined and i~ ~hown in Figure 12.
It i5 ob~erved from the graph of ~igure 12, that as frequency i5 increaeed, the required dieplacement i9 reduced, therefore high operating frequenciee are preferred.
Although operating frequency and amplitude can be selected to induce cavitation at the dietal tip 16, another preferred mode of operatlon i9 to operate the catheter assembly with a frequency and di~tal tip displacement lec~ than required to induce cavitation.
Thi~ low frequency mechanical energy mode ha~ been 2083~2~

obgerved LO be very effective in recanalization of occluded ve3sels. In a present embodiment, a preferred operating frequency of the system is 540 Hz with a tip a peak to peak displacement of 0.100 inches.
Since the operating frequency is proportional to stiffness and inversely proportional to system mass and damping, if a higher frequency i~ preferred, this can readily be provided by either increasing the stiffness of the spring or decreasing the sy~tem mass and damping.
If desired, the peak-to-peak di3placement of the tip 16 oscillation can be ad~usted down from approximately 0.100 to 0 inches.
In addition to driving frequency and amplitude, another consideration in control system operation and performance relate~ to the driving system waveform. In the operation of the driving apparatus 18 to occillate the core wire 32, it is advantageou~ to minimize the magnetic resi~tance of the magnetic circuit. Accordingly, the ma~ 122 ic drawn into the center of the magnetic pole gap 176 ~of Figure 10). As the ma~ 122 is moved from its re~t po~ition, a reaction force i~ generated on the mass by the epring 130. Upon reaching pole center, the magnetic field is removed or shut off and the spring 130 attempts to restore the mass 122 to the re~t poeition. m rough the u~e of digital control in the power circuit of Figure 8, the magnetic field is energized at a frequency at or below the sy~tem's mechanical natural frequency. The proce~s of pulling the ma~s proximally i~ repeated at this operating frequency. In one embodiment of operation, this process repeats itself at a frequency of 540 times per ~econd. The driving apparatus 18 and .
. . . . . .
.
-.: ~

2083~2~

the power ~inusoid excitation wave form allows the sy~tem to be driven with an electrical signal of 270 Hz, or 1/2 of the mechanical operational frequency.
Referring to Figures 13a and 13b, there are S graphs of two alternative embodiments of the driving signal that may be output from the drivlng circuit of Figure 8 to the solenoid to impart axial movement of the core wire 32. In the first embodiment of operation, the driving ~ignal includes a series of pulses with each pulse having a relatively high initial spike to impart rapid current increase in the coil of the solenoid. The high initial spike is followed by a flat pulse. In this embodiment, each pulse may also include a relatively sharp reverse spike at the end of the pulse to shut off the solenoid force. The waveform deplcted in the graph of Figure 13b is another alternative embodiment of the operating mode. The embodiment of Figure 13b shows a driving circuit output slgnal with a square wave. Application of a force on the proximal end of the core wire to move it distally is provided by the recoil action of the spring in cooperation with the operation of the magnetic oscillation of the proximal mass. In a present embodiment, a sinusoidal wave form is preferred.
In alternative embodiments, the driving apparatus could be operated to move the core wire in a di~tal direction by application of force on the proximal portion of the wire, instead of relying upon the reaction by the ~pring to move the core wire di~tally. Alternatively, the driving apparatu~ and the spring could combine to move the core wire distally.
Alternatively, a distal force may be applied by a 2083~2~

combination of both the ~pring 130 and the driving apparatus.

3. Tip displacement audio feedback During normal operation of the driving apparatus 18 to impart axial oscillation to the core wire and tip, the ~ystem generates an audible sound that i~ loudest during maximum tip dieplacement. This coincides with maximum energy delivery to the site of the vessel ob~truction. In a preferred mode of operation, the system 10 should be operated at maximum tip displacement to deliver the maximum quantity of energy to the vessel site. ~ecause the system is relatively quiet during operation, the audible feedback from the sy~tem may be obscured by ambient noise levels in a typical catheter lab. As a means of providing tip dlsplacement feedback, an audio output from the ~olenoid is preferably incorporated into the system.
The physics of operation of the ~olenoid produce a variance in the solenoid current requirements as the proximal mass 122 moves through the magnetic gap.
U~ing thi~ current level fluctuation as a control to monitor the oscillation of the proximal mass in the gap and ~imilarly the displacement of the distal tip, a tone signal can be generated whose tone or level would represent tip displacement levels.
An alternate method of displacement monitoring would be to mount a small vibration pickup, similar to a phonographic needle, on the wire support tube 34 and monitor the dietal tip energy directly and ~0 calibrate its output to tip displacement. Again the pickup's output would be routed to an audio amplifier ~ . .
,,, ', ' .

' ', ' ' , .

~083~2~

for generation of a tone which would indicate an acceptable tip di~placement.

4. Particle removal in aeneral According to a further aspect of the present embodiment, there is provided a means for fluid particle removal from the site of the vessel obstruction proximate to the distal tip 16. Fluid removal from the di~tal tip 16 provides for the removal of particles, such a~ particles of the unde~ired material that break away upon application of low frequency mechanical energy or cavitation. Thi~
function i8 provided in part by the flushing action of pressurized fluid 41 as it i8 applied to the distal tip from the first (or supply) tube 34 and withdrawn by the particle removal sheath 36. This fluid removal action utilizes at least in part the Coanda effect.
The fluid is ~upplied under pressure to the manifold a~sembly 42 by the hydraulic pressure source 22. In a preferred embodiment, the hydraullc pressure source 22 i8 a supply pump that delivers saline fluid at an output rate of up to 200 mL/minute at a pressure that is variable at approximately 1 kpsl or less. The fluid fills the supply tube 34 including the pressure chamber 128 of the housing 126. In the first embodiment, preesurized fluid 41 e~capes the supply tube 34 at the distal opening 72 and is directed at the distal tip 16.
The location of the particle removal sheath 36 relative to the distal tip 16 is important for proper particle removal flow performance around the distal tip 16. Referring to Figure 3, in the present embodiment the distal end of the particle removal .
-2 0~3~!2 ~

sheath 36 i 0.05 inches from the proximal edge 158 of the distal cap 150 during operation. In a present embodiment, the particle removal sheath may be moved relative to the supply tube 34. Movement of the particle removal shea~h 36 from the preferred position relative to the supply tube 34 reduces the particle removal effect.

5. Operating pressure The ~ystem 10 with fluid particle removal operates with a preferred inlet 42 pressure of 1000 psi or less. This operating point has been defined by using conventional fluid dynamic relations with preferred geometr$es in order to attain a mild particle removal effect at the device distal tip. The operating pressure can be increased or decreased based upon the desired particle removal effect. Increasing the pressure results in higher particle removal and more turbulence around the distal tip 16. Convereely, decreaslng the operating pres~ure reduces the amount and severity of particle removal.
The operating pressure i~ also influenced by the core wlre 32 and supply tube 34. If a core wire of a larger dimension i8 used with a supply tube 3g having the same internal diameter, the required supply pressure lncreases in order to obtain the same distal exit pre~sure. The opposite is also true, as the wire size is reduced supply pressure requlrements drop.
Depending on the desired particle removal effects and distal fluid mixing, the operational pressure can vary from 500 to 1 kpsi or less.
In an alternative embodiment of the mode of operation, a vacuum could be applied to the second port 208352~

44 to reduce the proximal supply pressure requirements while maintaining the same pressure differential between the supply and particle removal ports. m us, the proximal ~upply pres~ure requirement would be reduced to les~ than 1 kpsi, for example. Application of a proximal vacuum could require a change in the construction of the particulate transmission sheath 36.
The sheath 36 would be required to support a high hoop stress and therefore a con~truction of a hypotube or composite construction may be preferred. In this alternative embodiment of the operating mode, obstruction ablation would be accompllshed with the distal tip mechanical movement and a distal orifice.
Particulate tran~mission proximally would be accomplished through the combined efforts of the vacuum and distal return orificec.

6. Operating fluid At pre~ent, ealine i~ the preferred fluid 41 of operatlon. Saline paeee~ the low ~l~co~ity and bio-compatibility required for the ey~tem operation. As apo~sible alternatlve, a lower vi~co~ity, bio-compatible fluid could be u~ed. In thie fa~hion, a gae ~uch as CO2 could be u~ed. If CO2 were u~ed, it would be important to recover 100% of any CO2 gas input to the system along with any additional fluid attached viscously. m e ga~, euch ae CO2, ehould be bio-diffu~ible (i.e., quickly abeorbed into thé blood stream). The ga~ may be routed through a lubricating reservoir to promote a lubricated wire/~upport tube interface. Use of a ga~ may require a tightly controlled distal cap having a proximal annular edge to 208352~

promote the Coanda effect for flow attachment to the distal wire aupport tube 34.

7. Mode of particle removal The present embodiment utilizes two modes of energy transfer for particulate retrieval and removal.
The first inherent form of energy into the system is a relatively low velocity, static pressure head flow through the fluid from the hydraulic supply pump 22.
As the fluid 41 moves through the system, this low velocity and static pre~eure i8 exchanged for a high velocity, low static pressure head energy at the proximal and distal particle removal ports. The ports act as a means of converting any potential head or static head to a kinetic head or velocity head. This conversion to velocity promotes viscous attachment of surrounding particles into the supply fluid and their movement distally with the operating fluid. This viscou~ attachment yields the distal particle removal zone around the distal tip of the device. As the operating fluid moves proximally, the kinetic head 18 converted back to a ~tatic head pushing the fluid proximally.

~. ~upply fluid modul~ion In the present embodiment, the ~upply fluid 41 is stopped during tip oecillation. The fluid 41 can act as a hydraulic damper during ~upply flow thereby impeding tip oscillation. A~ a ~olution the fluid supply may be modulated such that the fluid is supplied at times corresponding to when the driving apparatus is ~0 off. This modulation of fluid supply can be accomplished using a manual valve activated either by - 4a -2083~2~

hand, pneumatics, or electronic~ to turn the flow on and the magnetic circuit off. The modulation could also be accompli~hed by an electronic controlling circuit which e~entially controlled the frequency at which the fluid is turned on and off in sequence with the driving apparatus. Present valved technology would limit the operating frequency of thia fluid modulation.
Prequencies attainable today at pre~sure~ vary from low (less than 1 Hz) u~ing a manual valve to very high (up to 1 Khz) u~ing a bobbin type valve. A~ an alternative, the fluid ~upply could be modulated by a solenoid. The fluid modulation aolenoid could be continually on and di~tal mass o~cillation would begin when the fluid flow was halted.
In an alternative mode of operation, after cro~sing a lesion, preeaure to balloon during inflation could be modulated to provide a low frequency (0-1000 Hz) balloon profile oscillatlon.

9. Catheter Bxchange It eometimes lo neces~ary during intrava~cular procedurea to exchange a fir~t lntravaecular device for another. Thia may be neces~itated by a need for a different device, or for a device with different dimen~$ona or a different bend at the tlp. In the present embodiment, the catheter as6embly 14 can be exchanged for another, if deaired, or for a ~eparate different intravascular device. In order to exchange a firat catheter aeaembly 14 for another, an exchange eheath 180 may be utilized, a~
illustrated in Figure 14. The exchange ~heath 180 would be poeitioned over the outaide of the catheter a~embly 14 before the catheter assembly 14 ia 208352~

positioned intravascularly. Then, the catheter assembly 14 i~ positioned at the ~ite of the va~cular ob~truction. A conventional guide catheter may be used for thi~ ~tep. Then, the distal tip i~ oscillated and the catheter a~embly and tip are advanced through the obstruction. Then, the exchange ~heath 180 i~
po~itioned past the di~tal tip and over the lesion site after the distal tip 16 has cro~ced the le~ion. Then, the catheter as~embly i8 withdrawh from the exchange ~heath and the ~econd intravascular device i9 po~itioned through the exchange ~heath acro~ the lesion. Then, the exchange sheath may be withdrawn at lea~t partially. The ~econd intravascular device could be a balloon dilation catheter, an atherectomy device, or other therapeutic or diagno~tic device, including a second catheter acsembly with an o~cillating tip. The exchange ~heath 180 would preferably have a di~tal profile with tapered edge~ 182 to facilitate exchange.
The exchange sheath 180 may be formed of high density polyethylene ~HDPE) and have an outer diameter of 0.041 inche~ at the tip and an inner diameter of 0.036 inches. The proximal portion of the exchange sheath 180 may have an outer diameter of 0.059 inches and an inner diameter of 0.053 inche~.

10. Alternative method of operation Although the precent embodiment ha~ been described in terms of its utility for the recanalization of an ob~tructed ve~sel by the application of low frequency mechanical energy or cavitation to the ob~truction, along with removal of broken off particle~ by vi~cou~ attachment by fluid particle removal, there are other way~ to uee the 208352~

present embodiment. For example, the present embodiment may be used in conjunction with other therapeutic device3 to treat a vessel obstruction. As an example, the present embodiment may be used to e~tablish a pa~sageway through a severely obstructed vessel. Some ves~els are co ~e~erely obstructed that it is difficult or imposslble to get a conventional balloon dilation catheter across the obstruction. The present embodiment could be used to cross such a severely obstructed vessel because the present embodiment is capable of forming a passageway through the obstruction. Then, the catheter a~sembly of the present embodiment could be removed and a conventional balloon catheter could be installed through the passageway in the obstruction formed by the present embodiment. Then, the balloon catheter could be used ~o dilate the vessel at the cite of the ob~truction.
Thus, the cliniclan-phy~ician could be afforded the opportunity to use conventional balloon dilation techniques in location~ previoucly inacceesible to balloon catheters and to choose ceveral different therapies to provide the bect treatment as indicated.

II. T~E NO~-PARTICLE REMOVAL SYSTEM
A. In general In a first alternative preferred embodiment, the particle removal function may be eliminated.
According to this embodiment, i.e. a "dry" cy~tem, in some circumstances, it may be considered unnecessary to provide for removal of particles that become broken off of the undesired material. This may be due to the type of materlal being treated, the location of the material being treated, concurrently administered treatments .

(i.e. medication~) to reduce the likelihood of complications of ~uch broken off particle~, or optimization of energy delivery to reduce the likelihood of particulate generation. If such factors indicate that the particle removal function is not necessary, an alternative embodiment of the present invention may be provided in which the catheter a3~emb1y 14 doe~ not provlde a pressurized fluid via the tube 34 or a return via the ~econd tube 36 for particle removal. In a non-particle removal embodiment, the operation of the system would be elmilar and treatment would proceed in a manner similar to that of the embodiment with particle removal described above except that there would be no provision for fluid and/or particle removal. Accordingly, in the non-particle removal system there would be no need to provide for the supply pump and fluid outlet.

B. ~upport tube in the non-particle removal embodiment In the non-particle removal embodiment, because the annular region between the core wire 32 and the fir~t tube 34 is not ùsed for conveyance of pressurized fluid, it is preferred that a ~maller distance be provided between the core wire 32 and the ~upply tube 34 compared to the system with fluid particle removal. In a preferred embodiment of the non-particle removal system, thi~ may be done by provlding a supply tube with ~maller dimensions compared to the ~upply tube in the embodiment with fluid particle removal. In the non-particle removal version, the first tube 34 may be formed of first and second sections as in the particle removal embodiment ,. , X0~35~a described above. Referring to Figure 4a, in the non-particle removal embodiment, the supply tube section 78 has an outer diameter of 0.036 and an inner diameter of 0.026. The Rupply tube distal section 80 has an outer di~meter of 0.014 inches and an inner diameter of 0.007 inches for the proximal 2 cm and an ouSer diameter of 0.011 inches thereafter. The proximal 1.3 cm of the distal section 80 fit~ into and therefore overlaps with the proximal ~ection 78. The bushing 81 has dimensions to accommodate the difference in diameters between the proximal and distal sections 78 and 80.

C. Core wire in the non-particle removal embodime~
As ln the embodiment with fluld particle removal, ln the non-partlcle removal embodlment, the core wire 32 include~ proximal and di~tal ~ectlons havlng different diameter~. In the non-partlcle removal version, the proximal ~ection of the core wire has an outer diameter of 0.010 inches and a length of 108 cm. In the non-particle removal version, the distal section of the core wire 32 has an outer diameter of 0.005 inche~ and a length of 35 cm. In a preferred embodiment, the core wire 32 i~ formed by grlndlng down a solld wire in the distal portion to form the distal ~ection of reduced dlameter.
In a pre~ent embodiment of the non-particle removal syetem, the annular region between the core wire 32 and the supply tube 34 i~ filled with ~aline.
This 18 done to reduce frlction between the core wlre and the flrst tube 34, to dampen transverse movements of the core wire 32 and qupply tube 34 due to core wire 2~3~2~

o~cillation~, and to reduce the presence of captivated air in the catheter as~embly. Saline i8 preferred due to it~ low vi3co~ity and biocompatibility. Other fluid~ could be u~ed which posses biocompatibility, low visco~ity, and good lubrication qualitie~. The saline i~ flu~hed into the area between the core wire 32 and the fir~t tube 34 via the fir~t port 42. Because this embodiment of the pre~ent invention without particle removal does not require a fluid pump ~ource 22, the ~aline may be flu~hed into the ~upport tube 34 from a ~yringe.
In addition, to further reduce friction between the core wire 32 and the wire eupport tube 34, a Teflon llner may be provided on the surface of the core wire 32 and/or a Teflon coating or liner may be applied to the inside ~urface of the wire ~upport tube 34. In addition to reducing friction with the core wire, the Teflon liner on the inner ~urface of the 6upport tube 34 provide~ for damping inside the wire support tube 34 for tran~ver~e wave attenuation.
Alternatively, a vapor depo~ition proce~ could be uced for adding a low frlction bearing ~urfaces to the inner surface of the wire ~upport tube 34.
In thi~ embodiment of the pre~ent invention without fluid particle removal, the port~ 82 and 84 and orlfices 85 on the flret tube would not be required and therefore would be omitted.

D. Damping sheath in non-particle removal embodiment In this embodiment without fluid particle removal, although the second tube 36 i~ not required to provide for the particle removal of fluid, the ~econd .
. -.
,. ;
-.

tube still provide~ a damping function for the catheter as~embly during axial oscillation of the core wire 32 within the first tube 34. In the embodiment with fluid particle removal, the return effluent occupying the volume between the fir~t tube 34 and the ~econd tube 36 contributes to the damping effect. In the embodiment without particle removal, a cuitable material may be provided between the fir~t tube 34 and cecond tube 36 to provide for damping. In one embodiment, the region between the fir~t and the cecond tube~ i~ filled with contra~t fluid or caline. Contrast fluid ic preferred because of its higher vi~cosity as well as its ability to be visible fluoroccopically.
Alternatively, other materialc may be used to provide for damping of any trancverce movement of the catheter assembly. Referring to ~igure 15, iD the embodiment without fluid particle removal, the volume between the first and the ~econd tubes may be occupied by a damping layer 190. In a present embodiment, the conventional constrained damping layer 190 is po~itioned between the wire cupport tube 34 and the damping ~heath 36. With the appropriate selection of damping material, the inner support tube 34 could be prevented from initiating tran~verce vibrationc induced by high cycle vibrations. Al~o cince the rectraining force i~ frequency dependent, static bending for positioning would realize e~centially no increase in device ~tiffnecc. The damping layer may be formed of a vi~cou~ fluid or a viccoela~tic solid. In u~ing a viscouc fluid, the viscoeity of the constrained damping layer could vary from air with a vi~cocity of 0.01~ cP
up to very vi~couY siliconec or other ~imilar materials whose viscositiec fall in the order of 70,000,0000 cP.

. , . ~, 2083~2~

Similarly in u~ing a vi~coelastic polymer, such as rubber, the selected material could be selected with moduli of elasticity ranging from 15 to 15000 psi to provide adequate damping and energy adsorption/storage to prevent transverse wave generation. Also, it may be necessary to provide a means for retaining the damping layer material in the volume between the first tube 34 and second tube 36. An adhesive seal 194 may be provided for this purpose.
Because the second tube 36 in the non-partlcle removal embodiment i~ not use~ for the withdrawal of effluent, it may be preferably provided with dimen~ions e~pecially ~uitable for the function(s) it perform~, e.g. damping. In this embodiment, the second tube 36 has an overall length of 132.7 cm. In the embodlment without particle removal, the ~econd tube 36 may be formed of section~ 102 and 104. These sections may be separate piece~ that are connected together or alternatively may be formed of a single plece of tubing necked, stretched, or otherwise processed to form sections of different inner and outer diameters. In the non-particle removal embodiment, the proximal section 102 of the second tube 36 ha~ an outer diameter of 0.042 inche~, an inner diameter of 0.037 inches, and a length of 98.3 cm. The di~tal section 104 of the second tube 36 ha~ an outer diameter of 0.024, an inner diameter of 0.014, and a length of 34.4 cm.

III. OTHER A~TERNATIyE E~30DDMENI~
A. ~mLlLg-9heath Al~ernati~e Embodime~a 1. Splines - -., ~ , ....

, ~

2~83~2~

In the above described embodiments, damping was provided by the second tube 36 and a material between the second tube 36 and the first tube 34. In the system with particle removal, damping was provided, in part, by the return effluent and in the non-particle removal system damping was provided, in part, by other materials. In an alternative embodiment, the wire support tube 34 could be encapsulated or fonmed in a polymeric tube 200 that provides damping and ~tiffness through the u~e of longitudinal splines 202 running the length of the catheter assembly. The polymeric tube 200 would replace and serve ~ome of the same functions as the second tube 36 de~cribed in the embodiments above. The splines 202 would be tapered in diameter as the distal portion of the shaft is reached to improve dlstal flexibility. The u~e of splines 202 would allow an increase in the proximal stiffness of the device while maintaining a sub~tantial area 204 for contrast flow around the devlce during angiography operation.
The outside diameter of the splines 202 would be sized such that the device could be used in a conventional a Fr guide catheter. The spline~ 202 may be incorporated into the inside wall of the second tube 36 or alternatively may be used as a sub~titute for the second tube 36 in a device that does not include a fluid particle removal sy~tem.
In an alternative in which the splines 202 replace the ~econd tube 36, the conventional guide catheter used for positio~ing the device may be used as well for additional structural ~upport. The guide catheter will provide a support against which the spline configuration of the polymeric tube can be dicposed against during operation. The epline 2083~

configuration of the polymeric tube 200 provides an adequate room for contrast fluid to flow around the spline configuration to the le~ion ~ite when it i8 in the guide catheter during angiography.

2. Rheological Fluid Referring again to Figure 15, in yet a further alternative embodiment, a rheological fluid could be u~ed as the damplng layer material 190. This alternative would provide for increa~ing device stiffnes~ and maintaining flexibility during po~itioning. The rheological fluid would be located in the annulus between the wire ~upport tube 34 and the damping sheath 36. A rheological fluid po~sese~ the feature of e~entially changing phase, from fluid to solid, when expoced to an electrical field. When the electrical field i~ removed the materlal returns to its original fluid ~tate.
Incorporating thie feature into the damping sheath 36 would allow the catheter aeeembly to be located within the va~culature and then to be fixed using an electrical field providing a stiff outer member during device operation for improved wire tranclation. The location of the rheological fluid annulu~ in terms of di~tal po~ition could be any length ba~ed on the device performance requirement~ and requlred longltudinal ~tiffening. For u~e of the rheological fluld, a metalized ~urface 192 on both the wire support tube 34 and the damping ~heath 36 would be requlred to eetabli~h the appropriate electric field acro~ the fluld medium 190. Thl~ would be ~imilar to a coaxial capacitor.

.

. ., ', :' : : .

2083~2~

B. Distal Ca~ Alternative Embodimente Referring to Figure 17, there are depicted alternative embodiments for the profile of the ~urface 154 of the di~tal tip 16. Alternative profiles include flat 210, elight curvature 212, ~light linear taper 214, spherical 216 or large linear taper 218. Each of these profilee may be particularly euitable depending upon the eelected operating speed, dieplacement, and type of material being recanalized. In pre~ent embodiment~, the spherical face 216 and the flat face 210 are preferred due to their leading edge~ which provide a location for flow separation during the back stroke of the dietal tip to lnduce cavitation. The linear taper 214 or conlcal face 218 may be preferred in terme of greater penetration when operating below the cavitation frequency.
Referrlng to ~igures 18a and 18b, there are depicted alternative embodiments of the distal tip 16 having lncorporated thereln means for reducing the local pres~ure field around the dietal tip 16. In Figure 18a, bleed ports 226 extending through the dlstal eurface 154 of the tip are incorporated through the dlstal tlp 16. In Figure 18b, a permeable member 228 i9 incorporated in additlon to bleed porte 226.
The permeable member 228 extends over the bleed port~
226 through the dietal tip 16. Bleed ports 226 or the permeable member 228 are incorporated into the di~tal tlp 16 to promote a local low pres~ure field. In effect the bleed port~ 226 and permeable member 228 act ae pressure tape from the relatively high preeeure blood field outside the tip to the relatively low pressure field at the dl~tal return orlfice. These alternatives would be most effective in an embodiment . .
.

- 20~352~

~hat did not posse~s any port~, e.g. 84, proximal to the di~tal end cap, i.e. in embodiments in which all the supply fluid 41 being pumped would be redirected by the di~tal cap.

s C. Ad~unct Dru~ Thera~y Referring again to Flgure 3, in an alternative embodiment, the annular region 92 between the wire ~upport tube 34 and the damping sheath 36 can be used a~ a path for introducing ~arious drug or biological fluid therapie~ intrava~cularly to promote thrombu~ or fibrouc material di~olution and di~persal.
In further alternative embodiment~, drug therapie~ may be applied to a ~teno~ ite via the dl~tal tip 16 of the catheter a~embly 14. Pigure~ l9a, l9b, and l9c depict alternative dictal tip embodlment~ adapted for drug delivery. Flgure l9a ie an alternative embodiment of the distal tip having drug delivery port~ 230 extending therethrough to provide an immediate path to the le~ion ~ite. Thie path provided by portc 230 would be available during the procedure and lecion cro~ing.
In this embodiment, the drug therapy would be delivered vla the annular region 232 between the core wire 32 and the ~upply tube 34.
Figure~ l9b and l9c depict alternative embodiments in whlch the relati~ely high frequency oscillation~ generated at the tip 16 are harne~ed to in~ect drug therapies into the lesion ~ite. A pumping action could be generated by the moving core wire 32 or distal tip 16. In both the embodiment~ depicted in Figures 19b and l9c, a pumping chamber 236 i~ formed in the distal tip 16. The pumping chamber 236 communicate~ with in~ection port~ 23~ oriented .
. `,` ; , `' ' ' ' : -- ' : , 2~35%5 laterally from the end cap 150. Therapeutic drug~
could be introduced into the pumping chamber 236 by way of the annular region between the core wire 32 and the ~upply tube 34 or by another lumen provided especially for thi~ purpo~e, e.g. a~ ~hown in Figure l9c.
Referring to Figure l9b, a proximal chamber seal 240 i~
located on and connected to the di~tal end of the ~upply tube 34 in~ide the tip 16. The chamber ~eal 240 form~ the proximal ~ide of the chamber 236. Drug theraple~ ~upplied to the chamber 236 are in~ected in the ve~el envlronment through the ports 238 by the pumping action of the tip relative to the core wire 32.
In Figure l9c, the drug therapy i~ provided via a separately provided lumen 2g2 and delivered to the pumping chamber 236 via a port 244. The distal end of the core wire 32 i~ connected to a piston 24~ which move~ independently of the cap 150.

D. a~tal Sheath Guide Embodlment In the embodiment de~cribed above and depicted in Figure 3, the di~tal ~heath guide~ 112 are formed of a plurality of radially extending leaf springc. In a further alternative embodiment depicted in Figure 20, the di~tal ~heath guide may be composed of a thin wall hypotube 250 formed into ~trut~ 252 from the support tube 34 to the particle removal ~heath 36.

E. ~g~ ,e,~ Ma~ Q~lm~nt~
In the embodiment de~cribed above and depicted in Figure 6, the mac~ 122 i~ connected to the spring 130 to form a mas~-~pring ~y~tem 132 specifically constructed to cooperate with the driving apparatu~ to impart o~cillation to the core wire. In a 2083~2~

further alternative embodiment, the masc-~pring system may be composed of a mass associated with multiple ~prings. An alternative embodiment incorporating multiple springs in a ma0s-~pring cystem i~ shown in Figure 21. The multiple springs can be attached to the moving ma~s in either ~eries or parallel fashion. In the embodiment ehown in Figure 21, three springc are utilized. A fir~t ~pring 260 is connected to the proximal mass 122 and the spring bu~hing 60 in a location corre~ponding the that of the spring 130 of the embodiment deccribed above. In addition, a nested ~pring 262 i~ located interior of and coaxial to the fir~t spring 260. This spring may have a different spring con3tant and/or stiffness. A third spring 264 i~ located proximal of the ma~s 122 between the mass and a proximal wall 266 of chamber 128. All springs may have different ~pring con~tants and/or ctiffnesses.
These spring~ may be fabrlcated from various materials ranging from high ctrength stainlecs steels po~essing high endurance limits to highly efficient polymer~ such as dence rubber~ with storage efficiencies on the order of 90 per cent or combination~ thereof. These modificationc to the ~pring and its mounting would affect the operating freguency of the eystem due to their impact on system stiffAe~.
Attachment of the springs 130, 260, 262, and 264 to the mass 122 and/or ~pring mounting bushing 60 can be accompli~hed by any biologically compatible method, including bonding, ~oldering, brazing, or welding. The present embodiment u~es soldering.
In a further embodiment, the proximal mass 122 can be varied in size depending on the desired force performance required. The force available -: ,, , - ' " - -.
: . .

2083~2~

through the ma~s i~ directly proportional to the mass diameter. Mass diameter can be increased while reliefs in the mass can be provided to maintain the inherent mass size.

F. Embodiment with Dilation Balloon Referring to Figure 22, there 18 depicted a further embodiment 270 of the present invention in which a dilation balloon is incorporated onto the catheter asser~ly 14. As mentioned above, one way in which the system 10 may be used is to recanalize an obstructed vessel site 80 that a conventional dilation balloon can be installed acro~s the site in order to perform an angioplasty procedure. In the embodiment 270 of Figure 22, a conventional dilation balloon 272 is incorporated onto the catheter assembly 14. Thus, instead of withdrawing the catheter assembly 14 after an obstruction has been recanalized in order to install a dilation balloon catheter, the dilation balloon is already on the catheter a~embly eo that the phy~ician can proceed with the dilation a~ soon as the obstruction is crossed by the tip 16. This can reduce the time involved in treating an obstruction and also eliminate the need for crossing the obstruction again with a separate balloon catheter through the recanalized vessel. In the embodiment shown in Figure 22, the balloon 272 is bonded proximally at 274 to the second tube 36 and bonded di~tally at 276 to the first tube 34. In this embodiment, the annular region between the first tube 34 and the second tube 36 is used for conveyance of inflation fluid for the balloon 272 .
' G. Outer Sheath with exDanding tip Referring to Figure 23, there is depicted another embodiment of the present invention. In the embodiment of Figure 23, the damping sheath 36 is provided with an expanding tip 290. In this embodiment, the damping sheath 36 i~ used with a ~upply tube and core wire (neither shown in Figure~ 23a and 23b) in a catheter a~embly as in the embodiments described above. The expanding tip 290 may be provided by mean~ of incorporating a braid 292 into the material of the damping sheath construction. Tnis embodiment of present invention provides for facilitating exchange of lntravascular device~ for the treatment of a vessel obstruction. The expanding tip 290 of the embodiment represented in Pigure 23a and 23b provides for expanding the diameter of the distal portion of the second tube 36 from a first ~or ~maller) diameter to a second ~or larger) diameter. The fir~t diameter i8 the diameter at which the ~econd tube 36 is u~ed for the recanalization of an obstructed artery by the applicatlon of low frequency mechanical energy or cavitation, in a manner according to the embodiments described above. At the second diameter, the distal portion of the second tube is large enough 80 that the supply tube and di~tal tip may be withdrawn proximally from the second tube 36. Then, the ~econd tube may be used as an introducer ~heath to allow the positioning of another intrava~cular device to the ve~sel site.
The other intravascular device may be a balloon catheter, an atherectomy device, or even another supply tube with a distal tip.
In an exemplary method of use, the .~. .. .
:

--208352~

catheter a~sembly 14 incorporating the second tube with the expanding tip 290 in the first or smaller diameter i9 advanced to the vessel ~ite ob~truction as in the previously de~cribed embodiments. The di~tal tip is o~cillated to impart low frequency mechanical energy to the vessel obstruction or to cause cavitation at the ve~sel ~ite obstruction. The distal tip is advanced through the obstruction thereby recanalizing that portion of the ve~sel. After the distal tip and the portion of the second tube including the expanding member 290 is past the obQtruction, the expanding member 290 is expanded from the first to the second diameter so that the fir~t tube and distal tip can be withdrawn from the second tube. Then, a balloon dilation catheter is advanced through the lumen of the ~econd tube to the site of the recanalization. The cecond tube i~ withdrawn proximally leaving the balloon portion of the dilation catheter exposed to the recanallzation ~ite. Then, the balloon can be inflated to further treat the vessel obstructlon as in a conventional angloplasty. An advantage of the above descrlbed procedure i~ that after recanalization, a balloon catheter can be advanced across a vessel obstruction by means of the acces~ provided by the second tube thereby facilltating provision of therapy to the ~lte.

I. Core Wire Alternative Fmbodiments There are ~everal core wire alternatlve embodiment~ that may provide potentially lmproved constralned axlal stlffne~s and flexibility.
A flr~t alternative core wlre con~tructlon 19 ~hown in Flgure 24a. In the first alternative core wire construction, the core wire 32 could po~ess a profile in the form of a spline 300 such that the bending ~tiffne~ would be les~ in a given plane, e.g.
plane 302. The con~trained axial stiffne~s would not be compromised due to the addition of cpllnec along the core wire shaft. The number of splines could vary depending on the required stiffne~s for a given application. ~our splines may be suitable although fewer or more may be desired. Al~o the u~e of cplines would reduce overall cystem mas~ allowing an increase in frequency of operation for the system. In further alternative embodiments, the core wire crosc ~ection could pos3e~s a profile other than round or splined.
For example, the core wire profile could be triangular, square, rectangle, or other geometrically beneficial crocc sectlons. These alternative core wire embodlmentc may pocceco desirable features similar to the spllne profile embodiment.
A cecond alternative core wire construction 20 i9 shown in Figure 24b. In thi~ alternative embodiment, the core wire 32 would have a composite conctruction with a multiple lumen polymer extrucion 304 lnto which prestressed (radially) member~ 306 are installed to yield a stiffening force on the polymer lumen. Thic embodiment would allow reduction in the overall system ma~c due to the hybrid or composite construction o~ the core wire and variability in core wire stiffnecs baced on prestressing of the internal member. Thic embodiment would also provide for preferred bendlng planec, e.g. plane 302.
A third alternative core wire embodiment includes a composite ~haft using filament members as3embled ln a resin or polymer. A fiber orientation :

208352~
~ 67 -can sub~tantially increase a component~s stiffness in one direction while having a lesser impact on 3tiffness in other directions or axes. This attribute would be utilized to increase the con~trained axial stiffness of the core wire shaft while continuing to afford a lesser bending stiffness for flexibility.
A yet further alternative embodiment of the core wire 32 would be to form the core wire of a wire rope construction with a low coefficient of friction ~acket. The shear plane inherent to a rope construction would allow th$s alternative core wire embodiment to have good bending flexibility while maintaining a high con~trained axial stiffness.

J. operatl~g ~ ,AL~ LlL ~
Retrieval of the ablated particulate could be accomplished by using a rotational retrieval means similar to an auger effect. Through vi~cous forces on the fluid and the rotation of the partlculate tran~mission sheath 36 relative to the cupport tube 34, a vi~cous pump could be established to transport debri~
proximally. The internal profile of the particulate transmission sheath 36 could be modified to promote a viscous attachment and/or the profile of the ~upport tube 34 could also be modified to improve vi~cous attachment effect during relative rotation. In this alternative embodiment, the ablation of the obstruction would be accomplished through a combined effect of a distal orlfice and the mechanical movement of the distal tip. Particulate trancmission would be accomplished through the viscous pump and a proximal vacuum.

. . , 2~83~2~

It i8 intended that the foregoing detailed de~cription be regarded as illustrative rather than limiting and that it is understood that the following claims including all equivalent~ are intended to define the scope of the invention~

.....

Claims (31)

1. An apparatus for recanalization of a obstruction in a blood vessel characterized by the presence of undesired material at a site in the blood vessel comprising:
a wire support tube adapted to be positioned intravascularly in the patient, said wire support tube having a proximal portion locatable outside the patient's vessel and a distal portion adapted to be positioned in the patient's blood vessel at the site of the obstruction;
a wire located within and extending through said wire support tube, said wire adapted to move axially with respect to said wire support tube;
a tip connected to a distal end of said wire and extending distally from the distal portion of the wire support tube;
a driving apparatus positioned at said proximal portion of the wire support tube and adapted to impart energy to said wire located therein to move said wire in oscillation axially with respect to said support tube;
a second tube located around at least a distal portion of the wire support tube, said second tube adapted to damp transverse movement of the wire support tube or wire caused by wire oscillations.

2. The apparatus of Claim 1 in which said second tube is adapted to provide an annular region between an inner surface of the second tube and an outer surface of the wire support tube.

3. The apparatus of Claim 1 in which said second tube fits closely over the wire support tube and further in which the second tube includes a plurality of splines extending longitudinally on an outside surface thereof.

4. The apparatus of Claim 1 further comprising:
a pressurized fluid supply connected to said proximal wire support tube and adapted to convey pressurized fluid distally in said support tube along said wire to a distal opening of said wire support tube directed at a channel in said tip adapted to redirect the pressurized fluid from said wire support tube distal opening toward a distal opening of said second tube formed by the annular region between said wire support tube and said second tube; and an exhaust port connected to a proximal portion of said second tube and adapted to withdraw effluent from the second tube conveyed from the distal opening thereof.

5. The apparatus of Claim 1 further comprising:
a distal sheath guide located between the wire support tube and the second tube corresponding to a distal location thereof, said distal sheath guide adapted to maintain the second tube concentrically coaxially disposed about the wire support tube.

6. The apparatus of Claim 1 further comprising:

an inflatable balloon connected to the distal portion of the second tube.

7. The apparatus of Claim 1 further comprising:
a mass connected to the proximal end of the wire and adapted to be moved by application of a magnetic field from the driving apparatus; and a spring connected between the mass and the supply tube adapted to store energy from said mass and restore the mass position to oscillate the wire connected to the mass.

8. The apparatus of Claim 7 in which the driving apparatus further comprises:
a solenoid assembly positioned around the proximal end of the wire support tube and adapted to apply a magnetic field to the mass; and a control circuit connected to the solenoid assembly and adapted to drive the solenoid assembly.

9. The apparatus of Claim 1 further comprising:
a rheological material occupying an annular region between the wire support tube and the second tube; and a switchable electrical potential source connected across the wire support tube and the second tube and adapted to cause the rheological fluid to change from a first phase to another phase.

10. The apparatus of Claim 1 in which said tip further includes at least one port extending through a wall thereof from an inside chamber of said tip to the vessel environment outside said tip whereby a drug therapy provided through the wire support tube is conveyed via the inside chamber of the tip through the at least port to the vessel environment.

11. An apparatus for recanalization of a obstruction in a blood vessel characterized by the presence of undesired material at a site in the blood vessel comprising:
a wire support tube adapted to be positioned intravascularly in the patient, said wire support tube having a proximal portion locatable outside the patient's vessel and a distal portion adapted to be positioned in the patient's blood vessel at the site of the obstruction;
a wire located within and extending through said wire support tube, said wire adapted to move axially with respect to said wire support tube;
a tip connected to a distal end of said wire and extending distally from the distal portion of the wire support tube;
a driving apparatus positioned at a proximal portion of said wire support tube and adapted to generate a magnetic field to impart energy to said wire located in said wire support tube; and a mechanical energy storage member connected to the proximal end of said wire and adapted to store the energy received from said driving apparatus and to release said energy to said wire to move said wire in oscillation axially with respect to said support tube.

12. The apparatus of Claim 11 in which said energy storage member further comprises:
a mass connected to the proximal end of said wire and adapted to be moved by application of the magnetic field from said driving apparatus; and a spring connected between said mass and said supply tube adapted to store energy from said mass and restore the position of said mass to oscillate said wire.

13. The apparatus of Claim 11 further comprising:
a second tube located around at least a distal portion of said wire support tube, said second tube adapted to damp transverse movement of the wire support tube or wire caused by wire oscillations.

14. The apparatus of Claim 13 in which said second tube is adapted to provide an annular region between an inner surface of said second tube and an outer surface of said wire support tube.

15. The apparatus of Claim 14 in which said second tube fits closely over the wire support tube and further in which the second tube includes a plurality of splines extending longitudinally on an outside surface thereof.

16. The apparatus of Claim 15 further comprising:
a pressurized fluid supply connected to said proximal wire support tube and adapted to convey pressurized fluid distally in said support tube along said wire to a distal opening of said wire support tube directed at a channel in said tip adapted to redirect the pressurized fluid from said wire support tube distal opening toward a distal opening of said second tube formed by the annular region between said wire support tube and said second tube; and an exhaust port connected to a proximal portion of said second tube and adapted to withdraw effluent from the second tube conveyed from the distal opening thereof.

17. The apparatus of Claim 16 further comprising:
a distal sheath guide located between the wire support tube and the second tube corresponding to a distal location thereof; said distal sheath guide adapted to maintain the second tube concentrically coaxially disposed about the wire support tube.

18. The apparatus of Claim 13 further comprising:
an inflatable balloon connected to the distal portion of the second tube.

19. The apparatus of Claim 13 further comprising:
a rheological material occupying an annular region between the wire support tube and the second tube; and a switchable electrical potential source connected across the wire support tube and the second tube and adapted to cause the rheological fluid to change from a first phase to another phase.

20. The apparatus of Claim 21 in which the driving apparatus further comprises:
a solenoid assembly positioned around the proximal end of the wire support tube and adapted to apply a magnetic field to the mass; and a control circuit connected to the solenoid assembly and adapted to drive the solenoid assembly.

21. A method for recanalization of a obstruction in a blood vessel characterized by the presence of undesired material at a site in the blood vessel comprising the steps of:
positioning a wire support tube intravascularly in the patient so that a distal portion of the wire support tube is in the patient's blood vessel at the site of the obstruction;
imparting an oscillating axial movement to a proximal portion of a wire located within and extending through said wire support tube to as to cause axial oscillation of a tip connected to a distal end of said wire that extends distally from the distal portion of the wire support tube; and damping transverse movement of the wire support tube and wire by means of a second tube located around at least a distal portion of the wire support tube;
whereby the vessel obstruction can be recanalized by the oscillation of the tip.

22. The method of Claim 21 in which said step of imparting oscillating axial movement to the wire is further characterized by the step of:

oscillating the wire at a frequency and amplitude sufficient to cause cavitation at the distal tip positioned intravascularly.

23. The method of Claim 21 in which said step of imparting oscillating axial movement to the wire is further characterized by the step of:
oscillating the wire at approximately 540 cycles per second with a tip displacement of approximately 0.010 inches.

24. The method of Claim 21 in which said step of imparting oscillating axial movement to the wire is further characterized by the step of:
oscillating the wire at a frequency in the range between 100 and 5000 Hertz.

25. The method of Claim 21 in which said step of positioning a wire support tube is further characterized by the steps of:
positioning a guide catheter intravascularly;
and positioning the wire support tube through the guide catheter to the vessel obstruction.

26. The method of Claim 21 further comprising the step of:
advancing the wire support tube and distal tip through the vessel obstruction while the wire is being oscillated whereby the vessel can be recanalized.

27. The method of Claim 21 further comprising the step of:
after the vessel obstruction has been recanalized by oscillation of the tip, positioning a second intravascular device through the vessel obstruction via the recanalization.

28. The method of Claim 21 further comprising the step of:
after the vessel obstruction has been recanalized by oscillation of the tip, withdrawing at least the wire support tube and wire from the vessel site and positioning a second intravascular device through the vessel obstruction via the recanalization.

29. The method of Claim 21 further comprising the step of:
after the vessel obstruction has been recanalized by oscillation of the tip, withdrawing the wire support tube and wire from the second tube and positioning a second intravascular device through the second tube across the recanalization.

30. The method of Claim 21 further comprising the steps of:
conveying a pressurized fluid via the wire support tube from the proximal portion to the distal portion;
directing the pressurized fluid out a distal opening of the wire support tube at a channel in the tip;
redirecting the pressurized fluid into a proximal direction by means of the tip channel;

withdrawing the redirected fluid and any viscously attached particles via a distal opening of the second tube;
withdrawing the redirected fluid from the second tube from an exhaust outlet located in a proximal portion of the second tube.

31. The method of Claim 30 in which the step of conveying pressurized fluid is further characterized by the step of:
conveying fluid at a pressure at approximately 1000 psi.