WO2000051512A1

WO2000051512A1 - Hollow hot tip catheter

Info

Publication number: WO2000051512A1
Application number: PCT/US2000/005133
Authority: WO
Inventors: Richard R. Heuser
Original assignee: Sun Star Technology, Inc.
Priority date: 1999-03-01
Filing date: 2000-02-29
Publication date: 2000-09-08
Also published as: AU3384700A

Abstract

A system, and method for treating a stenosis or blockage in a bodily fluid passageway is described. The system includes a catheter (10), and a controller for generating radio frequency energy along a pair of output lines (40a, 40b), a monitoring circuit (70) for monitoring the phase of the radio frequency energy along the output lines, and an impedance matching circuit (60). A lumen is provided through the catheter in order to deliver a mandril (18), and internal electrode (26) therethrough. Also, openings (132, 138) in a distal end of the electrode (26) is provided for delivering a medicine into the body of the patient at the areas treated with radio frequency energy.

Description

HOLLOW HOT TIP CATHETER

Background This invention relates generally to the catheterized treatment of a stenosis or blockage in a bodily passageway such as an artery or the like, and more particularly the invention concerns an apparatus and method for determining the optimal placement of the catheter in the bodily passageway for treating the stenosis. The invention also relates generally to an apparatus and method for creating holes or channels in a hypoperfused area of a heart with a catheter tip energized by radio- frequency waves. The invention further relates generally to an apparatus and method for creating the holes in the hypoperfused area of the heart with a guidewire that transmits RF energy to create the holes and also is hollow with one or more distal openings for delivering a fluid, such as a gene therapy medicine, to the holes and the areas around the holes to promote revascularization.

A stenosis is a narrowing or constriction in a bodily passageway such as an artery. One such type of stenosis is known as atherosclerosis and occurs in blood- conveying arteries in humans. Heretofore there have been a variety of apparatuses and methods for treating such stenoses, such as mechanical, ultrasound and laser apparatuses and methods. All of these apparatuses and methods have in mind the ultimate goal of treating a stenosis so that it does not reoccur. The ultimate goal of these treatments is to unblock the stenosis so that it does not return so that a patient who suffers from such condition may go on to lead a normal life. The apparatuses and methods in the prior art have largely failed to achieve this goal because up until now, discovering the optimal placement of a catheter in a bodily passageway to achieve the most efficient heating of a stenosis has not been available. While the prior art apparatuses and methods have failed to determine the optimal placement of a catheter in an occluded passageway, the present invention has succeeded in providing an improved device and method which reduces the chances of restenosis or a reoccurrence of the stenosis.

A problem related to the stenoses in coronary arteries manifests as a hypoperfusion, or below normal blood flow, in one or more areas of the heart muscle, which are detectable by thallium scintigraphy. Lasers have been used to treat such hypoperfused areas of the heart by lasing the endocardial surface of the heart, for example in the left ventricle, to create small holes or channels part-way through the heart muscle, roughly perpendicular to the surface. The subsequent healing of the heart in the area of the channels is believed to involve the angiogenesis of small blood vessels, resulting in an increase in perfusion of the area. However, lasers designed for this technique are expensive, and the associated catheters are stiff and have an outer diameter that creates a risk of unwanted damage to the heart and blood vessels. Additionally, the catheters include a fiberoptic laser delivery device and are expensive, and can usually be

used only one time.

After lasing the endocardial surface to create the channels in the heart, the surgeon can remove the laser from the heart chamber, and draw it all the way back through the blood vessel through which it was inserted, and out of the body. Then the surgeon can insert an injection catheter through the blood vessel and into the heart, and attempt to align it with the channels that have been created in the endocardial surface and inject a medicine, such as a gene therapy medicine, which, if it reaches the area of the channels, tends to increase the amount of angiogenesis. This is a cumbersome procedure because it requires the removal of the laser, followed by insertion of the injection catheter through a lengthy pathway of blood vessels, and it is difficult for the surgeon to know when the injection catheter is aligned with the channels for optimal delivery of the medicine.

Jacobsen et al. (U.S. 5,833,632) describes inserting a conductor wire within the lumen of a catheter, where the catheter is also made of a conductive material and provided with openings along its length. Jacobsen requires that the wire and catheter be insulated from one another and be provided with a heating element coupling the wire and catheter at their distal ends for thermal treatment at a location in the body. Jacobsen also discloses that the openings in the catheter, when used without the wire and heating element installed, can be used to discharge medication within the body, but does not disclose how the catheter openings and conductor wire can be used together to deliver thermal treatment and medication to a location in the body. With the above problems in mind, it is an object of the present invention to provide an apparatus and method for the treatment of a stenosis which reduces the chances of a reoccurrence.

It is another object of the present invention to provide an apparatus and method for locating the optimal position in a bodily passageway for the treatment of a stenosis.

It is yet another object of the invention to provide a catheter for use in treating a stenosis which uses radio frequency energy to capacitatively heat the same.

It is a further object of the invention to provide a catheter and a controller for delivering radio frequency energy to the catheter, in which the controller includes a system for determining the optimal placement of the catheter in the bodily passageway.

Summary of the Invention

The invented system and method achieves the above results in the form of a catheter for the treatment of a stenosis in a bodily fluid passageway which includes a controller for generating radio frequency energy along a pair of output lines, monitoring the phase of the radio frequency energy along the output lines, and adjusting the output impedance so that it equals that of a load, e.g., the patient. The catheter includes a catheter body which is insertable into the bodily passageway and operatively connected to the controller. A lumen in the catheter body defines an opening and a mandril is disposed within the lumen so that a terminal end extends through the opening and into the bodily passageway. An internal electrode is joined to the terminal end of the mandril, with the other end of the mandril operatively connected to one of the output lines for receiving the radio frequency energy produced by the generator and delivering such energy to the terminal end and the internal electrode. An external electrode is located externally of the catheter so that when the radio frequency energy is delivered

via the mandril to the internal electrode, the same causes or enables the capacitative heating of a stenosis.

The method of the present invention relates to finding the most optimal position for placement of the catheter so that optimal power may be delivered to the stenosis. The method involves the steps of providing a controller, which includes a radio frequency waveform generator, an impedance matching circuit, and a phase monitoring circuit, the controller being operatively connected to the catheter and a grounding pad; inserting the catheter into a bodily passageway so that it is positioned adjacent a stenosis; tuning the impedance matching circuit so that the impedance of the generator matches the output load impedance; delivering a produced waveform to the catheter; and, adjusting the phase of the waveform so that it is substantially 180-degrees out of phase relative to the grounding pad.

The present invention also provides an improved device and method for percutaneous myocardial revascularization of hypoperfused areas of the heart muscle that are less expensive and safer than the laser-based devices and methods. The channel- creating portion of the device is a radio-frequency wire, for example, the mandril and internal electrode described above, which is insertable through a balloon catheter or a simple end hole catheter such as a Tracker ® catheter made by Target Therapeutics, Inc. of Fremont, California, a division of Boston Scientific, Inc. of Natick, Massachusetts. The balloon catheter or Tracker ® catheter is in turn insertable in a right Judkins catheter of 6-french size which can easily be inserted through a major blood vessel, for example, through the femoral artery, the abdominal aorta, and the aorta, into a chamber of the heart, for example, the left ventricle. The external diameter of the 6-french catheter is a third smaller than the 9-french catheter required for the laser-based catheters, reducing the danger of unwanted damage to the heart and blood vessels.

To create the channels in the heart wall, the radio-frequency wire is inserted into the heart chamber and its tip is brought into contact with the inner heart wall at a desired location. The controller with the radio frequency waveform generator is then adjusted for optimum energy delivery and a burst of energy is applied for about one second to bore a channel about 0.014-inches in diameter and about 3- to 4-mm deep. The tip position is then adjusted by longitudinal and rotational movement of the right Judkins catheter and the process is repeated to create a map or network of from about eight to about thirty channels, typically spaced apart by about one centimeter. The RF energy is safer because it is less likely than the laser to perforate all the way through the heart wall. Additionally, the controller and radio-frequency wire are considerably less expensive than the fiber-optic laser delivery device and laser.

The present invention provides an improved device for delivering a medicine to promote the revascularization of the hypoperfused area of the heart. The device includes a radio frequency wire with an electrode at its tip coupled to a radio frequency waveform generator. The wire, tip, and generator can deliver a waveform to the hypoperfused area with sufficient energy to bore one or more holes or channels into the heart. The wire and tip include a passageway therethrough for delivering the

medicine to the holes.

The present invention provides an improved method for treating internal tissues of a patient's body whereby a hollow, conductive wire having an electrode at its tip is inserted into the patient's body and maneuvered to a desired area for treatment and RF energy is provided to the wire's tip to bore one or more holes or channels in the area. A medicine is injected to the area, immediately after creating the holes or channels, through the radio frequency wire that has created the holes or channels.

These and additional objects and advantages of the present invention will be more readily understood after a consideration of the drawings and the detailed description of the preferred embodiment.

Brief Description of the Drawings Fig. 1 is a schematic representation of a first embodiment of the present invention being used on a patient undergoing treatment for a stenosis. Fig. 2 is a greatly enlarged view of a catheter according to a second

alternate embodiment of the present invention.

Fig. 2A is a greatly enlarged view of the catheter constructed according to the first embodiment of the present invention.

Fig. 3 is a view of the catheter of Fig. 2, in place in a bodily passageway such as an artery, in a position for treating a stenosis.

Figs. 4 and 4A are schematic representations of an impedance matching circuit suitable for use with the first and second embodiments of the present invention. Fig. 5 is a block diagram of the controller constructed according to the preferred and alternate embodiments of the present invention.

Fig. 6 is a sectional side elevation of a heart showing the radio frequency wire within an end hole catheter in a right Judkins catheter inserted through the aorta

and aortic valve into the left ventricle of the heart with the tip of the radio frequency wire abutting the endocardial surface in preparation for boring a hole, and also showing several holes bored into the heart by the radio frequency wire.

Fig. 7 is a pictorial view of a catheter guidewire or RF wire inserted in a

3 french transit catheter, which in turn is inserted in a 6 french guiding catheter, for insertion through a patient's arteries and aorta and into the left ventricle, the wire including an open distal end to a hollow passageway through the wire for delivery of a medicine into RF treated areas within the heart.

Fig. 8 is a pictorial view of the RF wire of Fig. 7, but with a closed distal end and a series of openings spaced along and about the wire near the distal end. Fig. 9 is a pictorial view of the RF wire of Fig. 7, but with a narrowing portion culminating in a needle point with a closed distal end and a series of openings spaced along and about the narrowing portion of the wire.

Fig. 10 is a side cross-sectional view of an alternative embodiment of the

RF wire of Figs. 6 and 7 wherein the coil at the tip of the wire is expanded at its distal end to provide the opening for delivery of the medicine, and the coil is attached to the wire by a stainless steel bushing and includes a safety ribbon wire welded to the coil and further includes a PTFE shrink sleeve around the bushing and all but the distal, expanded end of the coil, and a luer fitting is attached to the proximal end of the wire, which fitting is illustrated for convenience with a smaller relative size than would typically be used.

Fig. 11 is a side cross-sectional view of an alternative embodiment of the RF wire of Figs. 6 and 7 wherein the coil at the tip of the wire is expanded at its distal end to provide the opening for delivery of the medicine, and the coil is attached to the wire by a safety ribbon wire welded to the coil and to the wire, and includes a PTFE shrink sleeve around the wire and all but the distal, expanded end of the coil.

Detailed Description of the Preferred Embodiments The system and method of the present invention according to the preferred embodiment is shown in Fig. 1 where it will be appreciated that a patient is shown undergoing a percutaneous translumenal coronary angioplasty (PTCA) treatment procedure. Although the present invention is described in the context of a PTCA procedure, the invention has utility in a wide variety of medical invasive procedures. The preferred embodiment of the present invention is described and shown generally in Fig. 1 where a hot tip catheter 10 is operatively connected via output line 40a to a controller 40 which includes a radio frequency wave form generator 50. In the preferred embodiment generator 50 is a crystal-controlled single-frequency generator for supplying a 13.56 MHz signal to the catheter. Controller 40 includes a matching circuit 60 for enabling the output impedance of the generator to be controlled, and a phase monitoring circuit 70 for enabling the controller to monitor the voltage phase between catheter 10 and an external electrode 11 connected to controller 40 via output

line 40b.

A temperature monitor 80 is operatively connected to the catheter for monitoring the temperature thereof during the PTCA treatment of a patient and in the preferred embodiment is an integral component of controller 40. More specifically, monitor 80 is interconnected with the matching capacitor in order to search for a matching position which produces a rapid temperature rise of typically 1 degree/sec or larger, either manually, automatically or audibly and described in more detail below.

Catheter 10 is shown in more detail in Fig. 2 where it may be seen that the catheter includes a catheter body 12 having a balloon 14 secured thereto. Preferably balloon 14 has an inflated diameter of around 2 millimeters and a length of around 20 millimeters and is of the type which is suitable for invasive procedures such as will be described. Catheter 10 is shown in a position inside of a bodily passageway which is represented by the cross hatches on either side of balloon 14. A lumen 16 defines a distal end 16a which includes an opening into the bodily passageway. A mandril 18 having a first end 20 and a second end 22 is disposed within lumen 16 in an operative arrangement which allows the heating of a stenosis described in detail below. In the preferred embodiment, mandril 18 is a SUS316L heat-hardened stainless steel rod and may have a length from around between 10 centimeters to 400 centimeters. Typically, however, mandril 18 is around 180 centimeters in length and has a outside diameter of around 0.40 millimeters. Preferably mandril 18 is gold plated for conductivity and includes a teflon coating thereover to facilitate the mandril's manipulability and steerability. Alternatively, in place of teflon, a material such as polystyrene may be used

which has the desirable characteristic of high capacitance. First end 20 includes a taper which terminates in a generally pointed region 24. In the preferred embodiment, the taper is around 10 centimeters in length. An internal electrode in the form of a coil spring 26 is preferably constructed of platinum and operatively connected to mandril 18 in region 24 such as by welding. Coil 26 is utilized for capacitatively heating a stenosis described in more detail below. It will be appreciated that for purposes of improved conductivity, pointed region 24 is devoid of the aforementioned teflon coating in the joinder region it shares with electrode 26. Alternatively, the coating, if electro- conductive, may extend over the joinder region and even internal electrode 26. Materials such as epoxy silver resin and aluminum film-coated polystyrene provide such a coating which is both electroconductive and highly capacitative.

Mandril 18 may alternatively be formed of beryllium copper, which provides both a low electric resistance, to minimize heating losses along the length of the mandril, and a high torque strength, so that the physician's rotating the mandril is transmitted along the length of the mandril to the internal electrode substantially without the mandril's deforming. A low resistance, high torque strength mandril may also be formed by combining gold or another low resistance metal, such as copper or aluminum, with steel, stainless steel, or another high torque strength metal, such as platinum

illinium (also known as platinum promethium) or MP35N, by plating, co-extruding, or simply by twisting two selected wires together. MP35N is a registered trademark for a cobalt-based alloy wire of Maryland Specialty Wire, Inc. of Cockeysville, MD. A thermocouple is provided in the form of a constantan wire 28 having an end 28a bonded to pointed region 24 of mandril 18, and another end 28b operatively connected to temperature monitor 80 (Fig. 1). Monitor 80, as mentioned above, is operatively connected to the matching capacitors and utilized to search for a position in which a high temperature rise, typically of 1 degree/second occurs indicating a condition in which the catheter tip is being optimally heated. The thermocouple may be formed by welding constantan wire 28 onto mandril 18. Additionally, a thermocouple sensor comprising a 50-micron copper wire and 50-micron constantan wire may be twisted together to form a 100-micron braid which is operatively coupled to the mandril across its length and anchored to the tip of coil 26 by epoxy adhesive. It will be understood that the epoxy adhesive may be electroconductive.

Energy collection structure in the form of a metal member may be placed near the 13.56 MHz conduction line, which in this case is mandril 18, for effectively collecting the electromagnetic energy by proper phasing of the electromagnetic wave standing in the mandril. Accordingly, the metal member may be heated up without any electrical connection to the mandril. Suitable for practicing an embodiment of the present invention is a single gold member or so-called marker, placed in a conventional PTCA catheter for heating the balloon and surrounding tissues. Fig. 2 shows a preferred embodiment of energy collection structure 30 in the form of a plurality of gold rings 30a through 30d which are spaced along catheter body 12 for collecting radio frequency energy provided by radio frequency generator 50 and through mandril 18 as described above. The rings preferably number more than two and each has a typical length of 1 millimeter. Another preferred embodiment of the present invention is shown in Fig. 2 A where it may be seen that collection structure 30 forms a second coil, preferably of gold,

having an inner diameter of 0.7 millimeters and suitably engaging lumen 16. The rings and spring may be constructed of any suitable material such as platinum and any suitable form of energy collection structure may be used.

In operation, catheter body 12 carrying balloon 14 is inserted, as shown in Fig. 3, into a bodily passageway such as an artery having a stenosis or constriction zone Z. Next, the optimal position for heating the stenosis is determined in order to effectively treat the occlusion thereby reducing the possibility of reoccurrence. In order to determine the optimal heating position in the passageway, the point of minimal reflectance is determined. Because the heating is capacitatively accomplished through the use of a 13.56 MHz signal applied to mandril 18 and coil 26 by controller 40, there must be a smooth flow of power in order to reduce the reflectance of the voltage wave. To minimize the reflectance of the wave and thereby optimally launch the wave into the stenosis or medium for effective treatment, there must be matching field patterns across the boundary between the signal source and stenosis Z. That is, impedance matching of generator 50 is a prerequisite component to place optimal energy across a hypothetical 50-ohm output load.

Digressing for a moment, it will be appreciated that measuring the reflectance of the voltage wave at the tip of the catheter, and more specifically at the tip of coil 26, is a difficult task. By recognizing, however, that the optimal placement, e.g., the true point of minimal reflectance may be evidenced by other indicators utilized in conjunction with generator 50 and matching circuit 60, such indicators may be

incorporated for use with catheter 10 for determining the optimal placement thereof. Such other indicators will be described below in conjunction with Fig. 5.

Shifting attention momentarily, the impedance matching aspect of the preferred embodiment will be discussed. It is generally known that maximum power transfer from a source to an output load takes place when the source impedance and the output load impedance are complex conjugates. In certain instances, as here, when the source and the load do not have complex-conjugate impedances, it is necessary to use an impedance matching device or network to manipulate the impedances so that the source impedance and the load impedance match. Referring now to Fig. 4, generator 50 is schematically represented with an internal impedance of Z_g = R_g + jX„ across two terminals a,b. Generator 50 is to be coupled with an output load, e.g., the patient undergoing treatment, having an impedance between terminals c,d of Z_L = R_L + jX_L. In order to maximize the delivery of energy to the stenosis, a condition must exist where Z_g = Z_L.

In practice, however, output load Z_L has been found, in the clinical situation, to range from between 100-ohms to 1-kiloohm, and to change further depending upon, among other things, the size of the patient, the placement of the catheter, and the length of the line leading to catheter 10 which may be as long as two meters or more. Matching circuit 60, a portion of which is illustrated in Fig. 4A, is connected between generator 50 and load Z_L, and enables the impedance seen by the source, e.g., generator 50, to be adjusted so that it equals Z'_L = R_g - jX_g; that is, R_L is transformed to a resistance R_g and X_L to a reactance -X_g. More specifically, matching capacitors 60a, 60b (Figs. 1 and 4A) have reactance values of X₂, X₃, respectively, and inductor 60c, a value of X]. By solving two simultaneous equations, the design values for R_ab and X_ab, where R_ab = R_g, and X_ab = -X_g may be determined. It will be appreciated that with such values determined and the impedance matched, maximum power may be delivered to the catheter tip in the most optimal manner. It will be understood that the impedance matching step may be performed manually, or automatically such as by a suitably dedicated programmed microprocessor as will be described.

It will further be appreciated that any suitable impedance matching circuit for the waveform frequency generated by generator 50 would do, and that the matching circuit may be reconfigured for other medical procedures which require different frequencies of energy.

Before launching the wave, the optimal position for the catheter must be found. This is accomplished through matching circuit 60 which includes an output voltage detector circuit, an output current detector circuit, and means for determining the

output impedance of the generator. It will be understood that if the catheter tip is not touching the stenosis, the impedance across the catheter tip will be different than when the catheter tip is in contact with the stenosis. During RF heating it is important to have firm contact with the tissue or stenosis because if the tip is floating in the blood, matching the impedance of the output circuitry is very difficult because it may be rapidly fluctuating. Thus, in order to efficiently and effectively heat a stenosis, there must be a good, firm contact between the catheter and the stenosis. It should further be understood that the catheter may be initially tuned, manually or automatically as mentioned above, while floating in the artery and then advanced to identify the stenosis (indicated by a change in the impedance seen by the source).

Once the impedance of the output line is properly matched, the catheter is in a position to deliver optimal energy to heat the stenosis. Now, by minutely adjusting matching capacitors 60a, 60b, in matching circuit 60, a phase difference of 180-degrees may be developed between the electrode or coil 26 and external electrode 11. By adjusting the matching capacitors as just described, power may be deposited with the highest efficiency at the tip of the catheter to heat the area adjacent coil 26. The adjustment of the capacitors may be accomplished manually by observing the phase over a suitable display, or automatically by a central processing unit programmed to tune the impedance network after positioning of the catheter tip as described above.

In accordance with another preferred embodiment of the present invention, controller 40 may also be seen in Fig. 5. The reader will observe that the controller is substantially the same as the controller described above except for some modifications to monitoring device 70 which will be described in detail below.

As shown, monitoring device 70 is operatively coupled to matching circuit 60 for the purpose of manipulating the matching circuit to maintain a matched impedance between the output impedance of controller 40 and that of a load. A logic processor 70a forms part of monitoring device 70 and is coupled to a device 70c described in more detail below. Processor 70a may be any suitable programmable processor such as a dedicated microprocessor programmed to determine the output impedance in response to input provided from device 70c, and in response thereto adjust matching circuit 60, and more specifically capacitors 60a, 60b so that a substantially

matched impedance condition exists between controller 40 and a load.

Logic processor 70a may also be provided with a sound or speech generator and linked to a speaker to provide audible, or otherwise sensible information to the physician as the catheter is operated and manipulated in surgery. For example, logic processor may keep track of the number of seconds of operation and report it out to the physician in any suitable manner, such as a generated-speech count. Additionally, logic processor may audibly or otherwise report the temperature at the stenosis or the impedance. For example, a repeating beep may rise or fall in pitch in accordance with the impedance of the load. The impedance of the load is believed to increase sharply as the tissue in the stenosis is successfully dessicated, and thus the corresponding sharp increase in the pitch provides a signal to the physician to switch off the radio frequency energy. Other catheter parameters may also be reported audibly or otherwise, such as ready-to-operate status or fault conditions.

Device 70c, according to one embodiment, assumes the form of a temperature monitor operatively coupled to thermocouple 28. The temperature monitor, by virtue of its sensitivity to differentially-sensed temperature conditions at internal electrode 26, determines rapid temperature rises, and in response thereto, enables processor 70a via connection 70b, to adjust the matching capacitors so that optimal heating may be achieved. Device 70c, according to another embodiment, assumes the form of an impedance monitoring circuit for determining the output impedance of the generator and adjusting the matching circuit so that the output impedance of the generator is substantially the same as the impedance of a load. Device 70c, according to another embodiment, assumes the form of a current flow monitor for monitoring the current flow from the generator and detecting changes related to impedance variations; and further, in response to such changes, adjusting the matching circuit via processor 70a so that the output impedance of the controller is substantially the same as the impedance of a load. Device 70c, according to yet another embodiment, assumes the form of an ultrasonic signal monitor which is capable of producing an ultrasonic signal and providing such signal to mandril 18, whereupon such signal is reflected from an area internally of the bodily passageway into which the catheter is inserted, and received by the ultrasonic signal monitor. In response to such received signal, the signal monitor enables processor 70a to manipulate matching circuit 60 for maintaining an impedance match between controller 40 and a load.

All of the above embodiments of monitoring device 70, and more specifically device 70c, (except for the phase monitoring circuit described above), provide for the indirect monitoring of the capacitative treatment of the blockage in a bodily passageway. Each of the devices, e.g., the temperature monitor, impedance monitor, current flow monitor, and ultrasonic monitor may best be understood by recognizing that the optimal heating point is close to the minimal reflectance point as measured by the output circuitry, but not exactly at the same point. Other indicators

provided by those devices discussed above, e.g., the embodiments of device 70c, provide a way to minutely adjust the impedance matching circuit in response to external variations, so that optimal heating may be achieved at the catheter tip. Such external variations, it will be understood, arise from such things as the variations in the length of the output line from patient to patient, variations in the load impedance experienced during capacitative heating, and so on. It will be further understood that the treatment and techniques described herein are also useful during treatment of a blockage insofar as determining impedance variations during the heating of a stenosis or blockage, and in response thereto, adjusting the matching circuit to accommodate such impedance variations.

It will further be appreciated that the embodiments discussed above are not so limited to applications in the 13.56 MHz range, nor to hot-tip/hot balloon applications. Rather the above-described embodiments will be understood to have a wide range of useful applications in all areas of medical practice in which it is desirable to treat body tissue or blockages in bodily fluid passageways with heat.

A method according to the preferred embodiment of the present invention involves the steps of providing a controller, which includes a radio frequency

waveform generator, an impedance matching circuit, and a monitoring device, the controller being operatively connected to the catheter and a grounding pad; inserting the catheter into a bodily passageway so that it is positioned adjacent a stenosis; tuning the impedance matching circuit so that the impedance of the generator matches the output load impedance; delivering a produced waveform to the catheter; and, adjusting the phase of the waveform so that it is substantially 180-degrees out of phase relative to the grounding pad.

Another method according to the preferred embodiment of the present invention involves the steps of providing a controller operatively connected to a catheter and a grounding pad located externally of a bodily fluid passageway, the controller including a radio frequency waveform generator, and impedance matching circuit, and a monitoring device operatively connected to the matching circuit for monitoring the impedance of the controller; inserting the catheter into a bodily fluid passageway so that the catheter tip is positioned adjacent a blockage which represents a component of the output load impedance; determining the output impedance of the controller; and adjusting the matching circuit so that the output impedance of the controller is substantially the same as the impedance of a load.

After heating the stenosis as just described, the stenosis may then be dilated by inflating balloon 14 as conventionally taught in U.S. Patent No. 5,344,398, the disclosure of which is herein expressly incorporated by reference.

Fig. 6 shows an apparatus for treating hypoperfused areas of the heart. The apparatus includes mandril 18 with attached coil 26 as described above, which together comprise a radio frequency wire 90. The mandril is connected to controller 40 and may include the end 28a of constantan wire 28 bonded to pointed region 24 of mandril 18, for the optimized application of radio frequency energy through the mandril to heat capacitatively the patient's body in the area adjacent coil 26, also as described

above.

The radio frequency wire is preferably inserted through a simple end hole catheter 116, with first end 20 and pointed region 24 of mandril 18 and coil 26 extending out of an open end 116a of catheter 116. Alternatively, radio frequency wire 90 could be inserted in balloon catheter 10 as shown in Fig. 2. In either case, the end hole catheter or balloon catheter is, in turn, inserted in a right Judkins catheter 112, typically of 6 french size. Coil 26 culminates at a distal end in a tip 92.

The catheters and wire 90 are inserted through a blood vessel into a chamber of the heart, for example, through the femoral artery, abdominal aorta, aorta, and aortic valve into the left ventricle. The selected chamber is one in which thallium scintigraphy has revealed a hypopro fused area 94 of heart muscle. Tip 92 is brought into contact with an inner wall 96 of the heart chamber at a desired location 98 as shown in solid line in Fig. 6. Matching circuit 60 in controller 40 preferably is then adjusted, as described above, to match the impedance of the load, to produce a 180° phase difference between coil 26 and external electrode 11, to optimize heating as monitored through thermocouple 28, and/or to optimize the ultrasonic signal reflection, and a wave of radio frequency energy, preferably about one second in duration, is applied to radio frequency wire 90. The radio frequency energy capacitatively heats the heart muscle at the contact point so as to bore a hole 100, preferably about 0.014-inches in diameter and about 3- to 4-mm deep. A map or network of from about eight to about thirty holes 100, preferably spaced apart about one centimeter, is created by repositioning wire tip 92 through longitudinal and rotational movement of catheter 112, as shown in dashed line, and repeating the optimized application of radio frequency energy.

After creation of the map of channels, wire 90 is removed and the heart is allowed to heal. The healing is believed to involve the angiogenesis of new blood vessels which will increase the perfusion of the formerly hypoprofused area, leading to improved heart function. The angiogenesis may be promoted by injecting a medicine, such as a gene therapy medicine, into the hypoperfused area adjacent the holes after creation of the holes. The medicine may be injected after using the above-described wire by removing the wire and inserting an injection catheter into the heart chamber in a manner similar to that for the wire, or the wire itself may be used for the medicine, as will now be described.

As shown in Fig. 7, mandril 18 and internal electrode 26, together comprising wire 90, may be hollow, defining a passageway 120 therethrough along the longitudinal axis of mandril 18 from its proximal end, where it is selectively operatively connected to output line 40a of the RF generator or to a conventional syringe for injection of a medicine through passageway 120, and through internal electrode 26 to its distal end at tip 92. Wire 90 is preferably between about 0.014-inches and about 0.021- inches in outer diameter, and most preferably is about 0.021 -inches in outer diameter. The inner diameter of wire 90 with an outer diameter of about 0.014-inches is preferably at least about 0.010-inches and may be as large as about 0.012-inches. The inner diameter of wire 90 with an outer diameter of about 0.021 -inches is preferably at least about 0.014-inches and may be as large as about 0.018-inches. The 0.014-inch wire may be inserted in a 3 french transit catheter 124, which in turn fits into a 6 french guiding catheter 126 for percutaneous insertion into the heart. Guiding catheter 126 may be a right Judkins catheter to facilitate rotational maneuvering of the catheter and wire as described above. The larger wires require selecting accordingly sized catheters. Wire 90 may include a nylon, polyethylene, or spray ed-on PTFE, coating 122 to reduce friction with, and insulate it from transit catheter 124. Coating 122, as shown in Figs. 7-9, preferably does not extend over tip 92.

Wire tip 92 may be provided with an open end 128 for delivery of the medicine adjacent holes 100, which will be understood to mean delivery to the area around holes 100 as well as into holes 100. In use, the surgeon may insert wire 90 within the catheters, as described above, and, with wire 90 operatively connected to the RF generator, maneuver tip 92 to a desired location in the patient's heart and deliver a waveform to tip 92 to create one or more holes in the endocardial surface of the heart. Wire 90 may include thermocouple 28 as described above, and the surgeon may operate the RF generator as described above for the optimal positioning of tip 92 and delivery of the waveform to the desired location. The surgeon or logic processor 70a may monitor the temperature of tip 92 and prevent an overheating condition by shutting off the generator when a maximum temperature is reached. After creating one or more holes, the surgeon may then disconnect the

RF generator, connect the syringe, and inject medicine through passageway 120. The medicine will exit wire 90 at open end 128 adjacent the one or more holes and be absorbed by the tissue there to promote angiogenesis. The surgeon may then either

repeat the process of creating holes and injecting medicine or remove the wire and

catheters.

As shown in Figs. 8 and 9, tip 92 may be shaped and provided with one or more openings to modify the delivery of medicine adjacent holes 100. The embodiment shown in Fig. 8 includes a closed, generally blunt distal end 130 and a plurality of lateral openings 132 spaced along and axially about tip 92, preferably within about 4- to 5-millimeters of end 130. The lateral openings allow the medicine to be distributed more diffusely, as compared to a single distal opening, to a wider area around holes 100.

It will be understood that the term "medicine" encompasses both vaccines, which are preparations for active immunological prophylaxis (prevention of a disease), and therapies, which are preparations for the treatment of a disease or disorder. The medicine may include a DNA-based, injectable fluid, also referred to as gene therapy medicine, or may include any other therapies or vaccines as appropriate

for the conditions being treated.

An alternative embodiment for wire 90 shown in Fig. 9 includes a narrowing portion 134 of tip 92 culminating in a needle point 136, which may be open or closed. A plurality of openings 138 are spaced along and axially about tip 92. Needle point 136 and narrowing portion 134 may be used to force tip 92 into the endocardial surface of the heart to mechanically create or start a hole 100, or to further enlarge a hole created by RF energy and to ensure injection of the medicine within the hole when desired. The openings of the embodiments in Figs. 7, 8 & 9 may be recombined with one another or altered as necessary to promote delivery of the medicine in a desired manner to the endocardial surface of the heart.

Another embodiment for wire 90 is shown in Fig. 10 where a stainless steel bushing 140 is fitted into passageway 120 at end 20 of mandril 18. Coil 26 is fitted onto bushing 140, and a thin- walled, PTFE sleeve 142 is heat-shrunk around bushing 140 and a proximal portion 144 of coil 26. A safety ribbon wire 146 extends along the interior of coil 26 from bushing 140 to the distal end of coil 26. Ribbon wire 146 is

welded at its ends to coil 26 to prevent coil 26 from unraveling, and at its distal end forms tip 92 for wire 90, which preferably includes closed end 130. Ribbon wire 146 can provide a bendable stiffness required for the surgeon to bend coil 26 to a desired angle for maneuverability. A distal portion 148 of coil 26 is exposed beyond PTFE sleeve 142, and the helix of the coil in portion 148 is stretched to allow a helical opening 150 for the delivery of medicine adjacent holes 100. Sleeve 142 prevents any leaking through coil 26 except at exposed distal portion 148, which preferably is about 5- millimeters in length.

Fig. 11 shows another embodiment of wire 90, similar to that of Fig. 10, but with coil 26 fitted into end 20 of mandril 18 and held in place there by brazing or welding coil 26, mandril end 20, and one or more safety ribbon wires 146. Wire 90 includes PTFE sleeve 142 heat-shrunk around lumen end 20 and proximal portion 144 of coil 26, and distal portion 148 of coil 26 is exposed beyond PTFE sleeve 142. The helix of the coil in portion 148 is stretched to allow helical opening 150 for the delivery of medicine adjacent holes 100.

The present invention provides a system and method which achieves many of the objects of the invention and which overcomes many of the drawbacks of the prior art. It should be understood that the invention is not restricted to the particular embodiment which has been described, since variations may be made without departing from the scope of the invention as defined in the claims.

Claims

I CLAIM:

1. An apparatus for treating a bodily tissue in a patient, the apparatus comprising: a controller including a radio frequency waveform generator for generating radio frequency energy along a pair of output lines, one of the output lines configured to be

coupled to the patient through an electrode; a radio frequency wire having a tip configured to be positioned adjacent the bodily tissue, the radio frequency wire operatively connected to the other of the output lines; the controller and radio frequency wire configured to deliver a waveform to

the tip with sufficient energy to bore a hole in the tissue; and wherein the radio frequency wire includes a passageway defined therethrough for delivering a fluid adjacent the hole.

2. The apparatus of claim 1 wherein the wire is configured to deliver the fluid into the hole.

3. The apparatus of claim 1 wherein the tip has an open distal end for delivery of the fluid adjacent the hole in the bodily tissue.

4. The apparatus of claim 1 wherein the wire defines a lateral opening for delivery of the fluid adjacent the hole in the bodily tissue.

5. The apparatus of claim 4 wherein the wire defines a plurality of lateral openings spaced along the wire.

6. The apparatus of claim 4 wherein the wire defines a plurality of lateral openings spaced axially about the wire.

7. The apparatus of claim 1 wherein the tip has a blunt distal end.

8. The apparatus of claim 1 wherein the wire tip has a narrowing portion near its distal end.

9. The apparatus of claim 8 wherein the wire tip includes an opening on the narrowing portion of the distal end.

10. The apparatus of claim 1 wherein the wire is no more than about 0.014" in diameter.

11. The apparatus of claim 1 wherein the wire is no more than about 0.021" in diameter.

12. The apparatus of claim 1 further comprising a first catheter for receiving the radio frequency wire and a second catheter for receiving the first catheter, the

second catheter configured to be inserted through a blood vessel and maneuvered to the bodily tissue.

13. The apparatus of claim 12 wherein the second catheter is no larger than a 6 french catheter.

14. An apparatus for treating a bodily tissue in a patient, the apparatus comprising: a controller for generating radio frequency energy along a pair of output lines, and an electrode connected to one of the output lines; a hollow tube configured to allow fluid passage therethrough, the tube having a tip configured to be positioned against the bodily tissue at a contact point, and the tube having a proximal end operatively connected to the other one of the output lines for receiving the radio frequency energy and delivering such energy to the tip with sufficient energy to bore a hole in the bodily tissue adjacent the contact point; and a fluid delivery system for applying a fluid through the hollow tube for treatment of the area adjacent the contact point.

15. The apparatus of claim 14 wherein the tube has an open distal end for delivery of the fluid adjacent the contact point.

16. The apparatus of claim 14 wherein the tube defines a plurality of lateral openings spaced along the tube for delivery of the fluid adjacent the contact point.

17. The apparatus of claim 14 wherein the tube includes a plurality of lateral openings spaced axially about the tube.

18. The apparatus of claim 14 wherein the tube tip has a narrowing portion adjacent its distal end.

19. The apparatus of claim 14 wherein the tube tip includes an opening on the narrowing portion of the distal end.

20. The apparatus of claim 14 wherein the tip has a blunt distal end.

21. The apparatus of claim 14 wherein the tube is no more than about 0.021" in diameter.

22. The apparatus of claim 14 further comprising a first catheter for receiving the tube and a second catheter for receiving the first catheter, the second catheter configured to be inserted through a blood vessel and maneuvered to the bodily tissue.

23. The apparatus of claim 22 wherein the second catheter is no larger than a 6 french catheter.

24. An apparatus for treating a bodily tissue in a patient, the apparatus

comprising: a controller including a radio frequency waveform generator for generating radio frequency energy along a pair of output lines, one of the output lines configured to be coupled to the patient through an electrode; a radio frequency wire having a tip configured to be positioned adjacent the bodily tissue, the radio frequency wire operatively connected to the other of the output lines, the controller and radio frequency wire configured to deliver a waveform to the tip with sufficient energy to bore a hole in the tissue; a first catheter for receiving the radio frequency wire and a second catheter for receiving the first catheter, the second catheter configured to be inserted through a blood vessel and maneuvered to the bodily tissue; and wherein the radio frequency wire includes a passageway defined therethrough and an opening adjacent the distal end of the wire tip, the opening in fluid communication with the passageway , the opening and passageway configured to deliver a

fluid adjacent the hole.

25. A method for treating an internal tissue of a patient's body, the method comprising the steps of: inserting a hollow, conductive wire having a distal tip into the patient's body and maneuvering the wire so that the tip is located at a desired area within the body for

treatment; providing RF energy to the wire tip of sufficient energy to bore a hole in the tissue in the desired area; applying medicine to the tissue adjacent the hole.