CA2204566C

CA2204566C - Apparatus and method for sterilization and embolization

Info

Publication number: CA2204566C
Application number: CA002204566A
Authority: CA
Inventors: Gregory H. Lambrecht; Thomas P. Ryan
Original assignee: Sherwood Service AG
Current assignee: Covidien AG
Priority date: 1996-05-14
Filing date: 1997-05-06
Publication date: 2001-07-10
Anticipated expiration: 2017-05-06
Also published as: CA2204566A1; FR2748648B1; GB2313062B; AU2084397A; GB2313062A; DE19719934B4; JP3928822B2; FR2748648A1; DE19719934A1; US6066139A; AU723252B2; GB9708729D0; JPH1043198A

Abstract

An apparatus (20) for transcervical sterilization or transcatheter embolization with a controlled bipolar RF catheter (21) for creating thermal lesions (22) in the fallopian tubes (23) or thrombosing vessels has a catheter (21) elongate along an axis thereof with a patient end (24). The catheter (21) is circular and sized for transcervical insertion into the fallopian tube or transcatheter vessel insertion, respectively. A connector (25) on an end of the catheter (21) opposite the patient end (24) has the terminations (26) for RF and monitoring and is shaped for the surgeon to manipulate during placement and withdrawal.
Two or more bipolar electrodes (29, 30 and 31)on the patient end (24) are placed so each electrode is spaced from another with each circumscribing the catheter (21). A mucosa or thrombus sensor responsive to applied RF energy passing between the two or more bipolar electrodes (29, 30 and 31)determines the condition of the transmural formation of a lesion or the thrombus between each of the electrodes. The sensor is a temperature sensor positioned in the space (34) between the electrodes measures the change in mucosal layer temperature or the thrombus during the application of RF energy. An RF generator (27) electrically coupled to the electrodes and the sensor is alternately a phase detector (35) in circuit with the coupling determines reactance of tissue as an indicator of lag or lead of the voltage wave form or current wave form delivered or is an impedance responsive circuit (39) positioned in the RF generator (27) to determine voltage and current delivered so a calculator finds impedance delivered for finding initial electrode contact with the tissue and for measuring the change in mucosal layer. A blunt tip at the patient end (24) facilitates introduction into the tube or vessel to avoid perforation. The temperature sensor connects to an RF generator (27) with control circuitry regulating delivery to a temperature range.
A proportional controller regulates the RF energy delivery to control temperature rise time and to maintain the temperature near the mid point of the temperature range. A method for sterilization has the steps of inserting a catheter (21), delivering RF and monitoring the effect on the mucosa or thrombus, circumscribing the catheter (21) with two or more bipolar electrodes, each of the electrodes spaced from one another and passing RF energy therebetween.

Description

- - .

APPARATUS AND MEI~OD FOR
ST~n T~TlON AND EMBOLIZATION

1. Field of the Invention This relates to an apya,~us and method for transcervical sterilization and tr~ ~~cath~,ter embolization. More particularly, a t~ el~tule controlled bipolar RP catheter and its use for creating t-h-ermal lesions in the fallopian tubes or ~rol~us in a vessel, ,~,ec ively.

2. Bac~ und of the Disclosure U.S. Patent number 3,840,016 has an electrocoagulation device for i~ e sterilization of the fallopian tube using a monopolar electrode and temperature control of just the electrode. U.S. Patent number 4,057,063 has a monopolar catheter to treat the fallopian tubes with impedance increase Illonilo"ilg to assess the completion of tre~ nt U.S. Patent number 4,411,266 is an RF lecioning electrode witb temperature sensor in the conductive tip. The system is monopolar. U.S. Patent number 5,486,161 is an RF
probe with heating through a hollow needle tip in monopolar fashion. U.S. Patent number 4,057,063 senses impedance of tissue in the vicinity of a monopolar electrode with a 5 second activation at 4.8 W with no control to lesion the entry from uterus to fallopian tubes.
U.S. Patent number 5,122,137 has a monopolar RF electrode with a temperature sensor buried therein. Circuitry measures temperature when the RF power is off. This electrode is used to thermally occlude the fallopian tubes.
U.S. Patent number 5,303,719 includes a delivery system for laser, electrical power or adhesive to the fallopian tubes. The electrical modality is monopolar.
U.S. Patent number 4,685,459 has bipolar forceps with temperature sensors on theelectrodes to limit the ,,,~xi,l,.. ,,, temperature of the tissue contacted during RF coagulation.
U.S. Patent number 4,685,459 is a bipolar forceps device with power controlled to the faces by buried thermal probes in the faces of the opposing forceps ends.
U.S. Patent number 4,700,701 is an electrically energized cautery of the fallopian tube followed by insertion of a plug. U.S. Patent number 5,095,917 has a bipolar RF

3 0 catheter to lesion superficially the mucosa layer near the uterotubal junction before a porous plug is inserted and there is no control of power and no lllo~ olillg during RF activation.
U.S. Patent number 5,303,719 destroys the inner layer of cells in fallopian tube and then uses suction to collapse and adhere the walls but there is no mention of RF energy of control.

U.S. Patent number 4,587,975 has an angioplasty catheter with cylintlrir~l electrodes used for l~ording ;--~p~~ e plethy~mogr~hy~ A thermal cautery probe for blood vessels with a ,esi~ ,e heater does not have RF. It is le.~c~dlure controlled by using a diode breakdown voltage. U.S. Patent number 5,122,137 conc~ tes current in theS vicinity of an electrode which must be thPrr~ ly corJ~,~(;vt; due to the thP,rmocourle buried inside herein a multiple electrode co..ri2~ dion has each elec~rode sensed.
Female sterili7~ion for the p,~,.c~ion of pr~,ldn~"y may be a ~P~e~ y procedure pelÇu,l,led Id~ vscûpically with ele~ ~us~-lge y. Typically, the fallopian tubes are grasped with bipolar forceps on the outside of the tube and ele t.~osu,gical energy is applied over a period of time until the surgeon sees the tubes coagulate. Following this, a second and third coagulation made on either side of the original extend the length of the coagulation.
Severa1 papers, published since 1878, disclose procedures that attempt to use heat to close the fallopian tubes. A hot probe cau~eliLed the opening of the fallopian tube from the uterus (tubal osteum). Later tplhniques with uncontrolled monopolar RF energy delivery sometimP,s failed. The use of a bipolar probe followed by pl~cPmPnt of a plug in uterine opening of the fallopian tube had no control of power and an nnin~ul~tpd tip of 1.5 mm length, thus operating at the edge of the fallopian tube and not farther inside the tube.
Sterilization requires ce,laillly with respect to the a~pa,dus and the procedure used.
The bac~,vulld herein ~liscussPs devices which fail to provide a level of cellaiuly because 2 0 the idea for each of the identified prior tel hniquP-~ and instruments was to seal the fallopian tubes with the ~lcd~..k~.l The less invasive approach disclosed herein recognizes that natural healing will produce a superior, reliable, dlrd.~ dic and consistent result not found in the prior patents or li~erdule.
Another use for this bipolar RF catheter device is for controlled use in blood vessels for embolotherapy. This would include sealing of arterial feeder vessels that couu"unicate with tumors in order to reduce the blood supply to the tumor either prior to surgery or as a treatment to necrose the tumor. In cases where congenitally formed vessels are anomalous, these would be sealed off by this catheter device. In the lung, anomalous vessels shunt blood flow and need to be closed. Al~eiovenous fistulas, pseudoaneulysl,ls caused by trauma or infection, hepatic artery-bile duct fistulas or sites of active hemorrhage are also applications for this device. In all of these examples, the application of RF energy will thrombose and occlude the vessel by heating the blood and the vessel wall to provide closure or sealing. Sylllp~oll-a~ic arterovenous malformations in the uterus is often treated by hysterectomy since it otherwise results in massive-vaginal bleeding and spont~neous abortions. -Embolization can prevent these u~t~ s. M~sive vascular hP~..o..l.~ge can result in multi-organ failure. Many of these patients are not candidates for surgery.
Several mPtho~l~ have been tried to ûcclude vessels. These include placing polyvinyl alcohol particles or metal flakes, de~ le starch, ~ oacl~late, ethanol, det: ~hAhle balloons, small coils or gelatin sponges. These tP~hni-lvP-~ all deal with a foreign body left behind with potential to migrate or flow out of the intPn~ed site. ~P~"~ ;OIl can also result with some of these ter,hniql]P~s. Precise control of coils during po~itioning or withdrawal is often challenging. Non-target tissue emboli7~ion results in tissue devitAli7Ation of normal structures. The only techniquff d~c-il)ed in the medical lil~,~lure for thermal embolization are the use of iron micros~hcres which are heated in an external radiofrequency field at 100 kHz. Another te~hnique w~ to use hot contr~t agents, as used in angiography, heated to 100 C. Yet another te~hniq~le used a laser with a metal cap to thrombose with heat and then leave the metal cap perm~ lpntly in place.
Patent 5,053,006 ~i~cmsP~s pe~.A~ occ~ on of arteries using a l~er. The technique involves injecting a dye into the vessel and then introducing l~er light at a wavelength to perform photo~hPm~ injury to the vascular endothelium. Patent 5,108,407 suggests placing a coil for embolization com e.,~ed to a r~berû~lic cable. Laser energy is introduced into the cable to melt the adhesive and rele~e the coil. Patent 5,354,295 also involves a coil placed for endovascular occlusion. The coil is then heated by flowing current between the electrode and the tip. Energy is activated until the wire disconnects from the coil. There is no mention of RF energy and the unit is not bipolar.
Patent 5,405,322 uses a balloon to heat the wall of an aneurysm. RF current flows between the electrodes to heat the fluid in the balloon which then heats tissue through thermal conduction. There is no RF energy flowing through tissue. Patent 5,437,664 is a 2 5 device for occluding the lumen of veins. The electrode is energized in a monopolar fashion and may utilize impedamce or temperature to signal the end of the treatm~nt No temperature of impedance endpoints are suggested. There is no control of power but only shutoff when endpoints are achieved.
The device described here will embolize by inserting the device into the vessel and precisely applying radiofrequency energy to heat the blood in the vessel to a controlled temperature for thrombosis and sealing of the vessel to occur. This autologous clot will not cause any foreign body reaction since nothing is left behind after the removal of the catheter.

SUMMARY OF THE INVENTION
To simplify this procedure and obviate surgery, an a~i)&dlus and clinical methodhave been developed that takes advantage of llallscel~icdl access and lecioning from inside-of the fallopian tube in a .ni.~;...~11y i~v~ive and controlled fashion that is not lld~lmdlic.
An a~p~dluS for L~a~sc~l./ical ste~ n with a contro11ed bipolar RP catheter for-creating thermal lesions in the fallopian tubes may have a catheter elonga~e along an axis thereof and with a patient end. The catheter is prer~ldbly generally circular in cross section and sized for tldnscelvical insertion into the fallopian tube. A connector on the end of the catheter opposite the patient end may include the ~e~ ionc for RF and monilOlhlg.
The coml~lor can be shaped for the surgeon to manipulate during transcervical pl~ce~-en~
and withdrawal. Two or more bipolar electrodes on the patient end of the catheter may be placed so each electrode is prefe~ably spaced from one another with each of the electrodes circumscribing the catheter. A mucosa sensor r~ollsive to applied RF energy passing between the two or more bipolar electrodes pr~Çeldbly deterTnin~s the condition of the t~ansl~ l forrn~tion of a lesion between each of the electrodes.
The mucosa sensor is in the prerelled embodiment a temperature sensor positionedon the patient end in the space between the two or more bipolar electrodes for 1~ ;--g the change in mucosal layer temperature during the application of R~ energy. An RF geneldlor could be electrically coupled to the two or more bipolar electrodes and the mucosa sensor is 2 O in this approach a phase detector positioned in the RF gene.dlor in circuit with the electrical coupling between the RF generator and the two or more bipolar electrodes for de~ g rea~t~n~e of tissue as an indicator of lag or lead of the voltage wave form or current wave form delivered to the patient end for measuring the change in mucosal layer as a tissue effect endpoint during the application of RF energy. An RF g~neralor is electricall coupled to the two or more bipolar electrodes when the mucosa sensor is an impedance responsive circuit positioned in the RF generator. The impedance responsive circuit in the electrical coupling between the RF gene.dtor and the two or more bipolar electrodes may determine voltage and current delivered and a calculator in the impedance responsive circuit for finding impedance delivered to the patient end for finding initial electrode contact with the tissue and for measuring the change in mucosal layer during the application of RF
energy.
In an embodiment there may be three electrodes connected to an RF geneldlor to deliver RF energy selectively between one pair of electrodes at one time to create a plurality of lesions therebetween inside the mucosal layer of the fallopian tubes. The catheter is most preferably flexible and might include a blunt tip at the patient end to facilitate introduction s into the fallopian tubes and to avoid perforation thereof. The temperature sensor could be conne~ed to an RF generator that has energy delivery control Cil~,uill.~ to regulate delivery of RF to a l~ml)GràlulG range of about 95 C to 105 C between the electrodes. The energy delivery control cir-,uill~y may include a p~po~ ndl controller for s~ ly regulating the RF energy delivery to control t~ ~dt . e rise time for lesion li~ ;. n and to .. ~2~
the temperature near the mid point of a tem~c~dturG range during thermal nec~sis of tissue for the tlallslllulal forrn~tion of a lesion.
A videoscope could s- llound the tldnsc~.~ically inserted catheter for the vi~u~li7~ion of the progressioll of the lesion via video. The tell-~.d~ure sensors are prereldl)ly located centrally relative to the axis within the space between adj ~ l electrodes.
The circular cross section of the catheter can be solid with the temperature sensors located at the center of the solid circular cross section of the catheter. The circular cross section of the catheter might be hollow having an inside and a outside wall of the catheter. The temperature sensors are then prerGIàbly located on the inside wall. The temperature sensors allel- a~ively can be located on the outside wall~ ~ The temperature sensors ~ ;vely can be located in the catheter wall~
The calculator may include a ."e..,ol~ in-~lu(1i~ an eludtion for the power delivery with respect to time and a co---i)ar~tor in the calculator to co-~-p~e power delivered to power required by the equation for closed loop control of the power delivered over elapsed time to shape lesion spread and shape~ The one or more bipolar electrodes are prerelably spaced apart to create multiple separate lesions inside the fallopian tube without moving the placed catheter. The one or more electrodes are possibly of dirr~,renl sizes so that when tissue contact is made the position near one of the electrodes is defined and the extent, depth and severity of the lesion formation plGr~ led results~ The eqn~ion in the memory prerGlably controls power to reduce sticking and charring to the electrode of tissue in contact therewith.
A method for transcervical sterilization with thermal energy delivery for creating lesions in the fallopian tubes may have steps including transcervically inserting into a fallopian tube a catheter elongate along an axis thereof and with a patient end, the catheter 3 0 generally circular in cross section and sized for the fallopian tube. The step of delivering RF and monilo,ing the effect of RF on the mucosa at a connector on the end of the catheter opposite the patient end may be included~ Circumscribing the catheter with two or more bipolar electrodes on the patient end of the catheter, each of the electrodes spaced from one another and passing RF energy between the two or more bipolar electrodes are steps~ The step of d~tv ~ E the cQ~ o~ of the t~ll,ul,ll rO.... ~ of a lesion between each of the electrodes with a mucosa sensor located between the electrodes is then followed.
The method step of transcervically i~hlh~g into a fallopian tube might bé
p~Çulll.~ by the surgeon manipulating during lla~sc~dcal plP~emPnt and withdrawal the com-eclo. shaped and located at the end opposite. The step of de~e~ ;ue the con~ ;ol- of the lld~lllulal formation of a lesion between each of the electrodes may include ",p~c ,, ;~lg impedance change during delivery of RF. The step of d~te~ ;ng the condition of the ul~ Çû~ à~iûll of a lesion between each ûf the electrodes could include ~--P~ g t~du,e change during delivery of RF. The step of d~e-...;.mle the condition of the ~ lulàl fo.. ~ ion of a lesion between each of the electrodes may include controlling leln~,e dule of the mucosa during delivery of RF to the range of about 95 C to 105 C. The step of controlling temperature of the mucosa during delivery of RF can include formation of a lesion ~h~ 1y through the wall of the fallopian tube. The step of collapsing the lesioned surface of the fallopian tube after withdrawal of the catheter followed by adhering with fibrosis the collapsed adjoining surfaces during a period of three to ten days after withdrawal is p,er~lably followed.
An a~alus for transcervical sterilization with thermal energy delivery for creating lesions in the fallopian tubes may include an elongate circular catheter with a patient end sized for transcervical insertion into the fallopian tube. One or more piezoelectric 2 0 tr~n~ducPrs are preferably on the patient end of the catheter so each piezoelectric transducer is a thermal energy source, each pie;Gulla ~sducP~r is a thin cylinder circumscribing the catheter and each pie~ot~ sducer is located to heat mucosa tissue. A connectQr on the end of the catheter opposite the patient end can include the te~ n~tions for piezoelectric energy and monitoring with the connector shaped for the surgeon to manipulate during transcervical p!acP-nnP-nt and withdrawal. A mucosa sensor responsive to applied thermal energy passing from the one or more piezotr~nsdnce-rs determines the condition of the llal~mulal formation of a lesion about the one or more pie~o~ duce-.~. The one or more pie;co~idl~ducers are preferably spaced axially from at least one qAjacent pie,o~ ducer.
Safe, effective, inexpensive minim~lly invasive method of transcervical tubal 3 0 sterilization could have a major impact on women's health. Unlike devices that include the insertion of a plug either with or without deposition of energy, the d~pa~dlUS leaves no foreign body in place after the lesion is created. Some techniques such as the mixing and application of an a&esive require a high degree of user skill and require the introduction of foreign material to the reproductive tract. Some devices endeavor to destroy cells along the 3 5 inner surface of the fallopian tubes while the device disclosed herein aims for limiting to lalllulal cell d~t~ ion. The fr~u~ c~ of RF ablation is .~ ed above 200 ldIz to avoid muscle or nerve stimv1a~ n Another major use of this device would be in ~ cr~hr,tr~r embolotherapy. This therapy is done by passing a catheter into a blood vessel and occl~lding the vessel by creating a tLolll~us to stop blood flow. This requires a flexible catheter with a hollow center for over-the-wire t~hniqnP-s.

BRIEF DESCRIPIION OF THE DRAWINGS
Figure 1 is a pel~pe~;live view of an dj~pa~atus for ~scelvical stP-rili7~iQn with a controlled bipolar RF catheter for creating thermal lesions in the fallopian tubes illustrated before insertion.
Figure 2 is a s~h~m~ic diagram of the Cil~;ui~ to control the RF energy responsive to thermal fe~lbac~
Figure 3 is a schç-m~tis diagram of the coupling to the lesioning electrodes with the RF genel~tol and the sensor f~j~)OIlSive Cll~;ui~ to control the lesion shape and extent.
Figure 4 is the trdllscei~vically inserted àpp~tuS having the patient end in thefallopian tube with the acco~ an~ing lesion passing t~a~ làlly.
Figure S is the a~paldtus transcervically inserted through the operating channel of a hysteroscope with the patient end observable entering the fallopian tube.
Figure 6 is the al)p~atus inserted through a prebent transcervical introducer tube exiting at the tubual ostium for entering the fallopian tube with the patient end of the d~ )~ aluS .
Figure 7 is a srh~ tic illustration of three electrodes showing the selective bipolar RF activation of certain electrodes to control the lesion location, si_e, shape and extent.
Figure 8 is a cross section taken along line 8-8 in Figure 1 of the gap between electrodes.
Figure 9 is a cross section taken along line 9-9 in Figure 1 of the location of the sensor.
Figure 10 is a cross section taken along line 10-10 in Figure 1 of the electrode on 3 0 the catheter.
Figure 11 is a cross section taken along line 11-11 in Figure 1 of the sensor in the catheter wall.
Figure 12 is a cross sectional illustration of a closed, lesioned fallopian tube.
Figure 13 is a schematic diagram of a phase detection circuit used for the control of 3 5 the application of RF energy.

Figure 14 is a partial p~l:~C~,liVe view of a piezoelectric element as would be carried by a catheter into the lumen.

DETAILED DESCRIPl'ION OF THE INVENTION
An apparatus 20 for l~ ical ~e~ with a controlled bipolar R~ catheter 21 for creating thermal lesions 22 in the fallopian tubes 23 shown in Figures 1, 4, S, 6 and 7 has the catheter 20 elongate along an axis "A" thereof and with a patient end 24. The catheter 21 is generally circular in cross section and sized for transcervical insertion into the fallopian tube as shown in Figures 4, S, and 6. A conne~;~or 25 on the end of the catheter 21 opposite the patient end 24 inrludes the wires and l~ lalions 26 for col~e~ lion to an ele~ o~ul~ical gen~r 27 shown in Figure 3 that supplies RF and controls the amount by llloni~u,h g. The connector 25 can be shaped like a handle 28 in Figure 4 for the surgeon to manipulate during transcervical pl ~empnt and withdrawal. Two or more bipolar electrodes 29, 30 and 31 on the patient end 24 of the catheter 21 are placed so each bipolar electrode 29, 30 or 31 is prererdbly spaced from each other with each of the bipolar electrodes 29, 30 or 31 circumscribing the catheter 21 as shown in Figures 1, 3, S, 6 and 7. The catheter 21 patient end 24 is flexible and a central part 24' of the catheter 21 between the patient end 24 and the connector 25 may be less flexible than the patient end 24 to aid in insertion through collapsed or cir~;uilous v~cnl~t~lre as in Figure 7.
A mucosa sensor 32 responsive to applied RF energy passing between the two or more bipolar electrodes 29, 30 or 31 determines the condition of the llal~l..ul~l formation of the lesion 22, see Figures 4 and 12, between each of the bipolar electrodes 29, 30 and/or 31 to thereby signal the elecllus.l,gical geneld~or 27 during lllûnilolillg for controlling the application of RF to the inside wall 33 of the fallopian tube 23. The mucosa sensor 32 is in 2 5 the pr~relred embodiment a temperature sensor, see Figure 1, pûsitioned on the patient end 24 in a space 34 between two or more of the bipolar electrodes 29, 30 and 31 for mP~llring the change in mucosal layer temperature during the application of RF energy. The RF
generator 27 electrically coupled to the two or more bipolar electrodes 29, 30 and 31 and the mucosa sensor 32 would in this approach include a phase detector 35 positioned in the RF generator 27. The phase detector 35 is thus in circuit with the electrical coupling between the RF generator 27 and the two or more bipolar electrodes 29, 30 and 31 for d~ llhlillg re~ct~nce of tissue as an indicator of lag or lead of the voltage wave form or current wave fûrm, see Figure 13, delivered to the patient end 24. The phase detector 35 thereby measures the change in mucosal layer 33 as a tissue effect endpoint during the 3 5 application of RF energy. The phase detector 35 is shown in Figure 13 and has two input voltages Vv~ a 500 kHz ~.a~fullll propo,i- ~' to the RF output voltage, and V~, a 500 kHz voltage proportional to the RF current output. Phase detector 35 has a phase lock loop that processes these two signals producing an output voltage (VO"~ p,opo,i --' to the phase betwveen the two inputs, thus giving the n~agnitll~e of the lead or lag of the phase angle between the two ~t;ru,uls. A change in this phase angle would imply that the c~pa~ilive or inductive CûlJl~)Ol C~ll, of the tissue has changed and this could be a marker that implies that the tissue is somciently coagulated. The gen&dt~r 27 supplying RF energy in a particular embodiment has activation controlled to en~oill~ of time, inli~eddnce, phase, or lelll~e,d~ure. Power, current, voltage, le.ll~c.d~uie rise and steady-state temperature are controlled for producing the desired leslonir~ effect in the mucosa layer 33. Several cycles are possible wherein multiple endpoints are achieved as milestones for lesion 22 creation.
The source of RF can either be a stand-alone generator 27 with a temperature fee~1back loop in Figure 3 as the,l,lo,-l~ processor 36 or an illelî~ce 37 in Figure 2 as a D to A
col,vellel that controls the power into the device from an external source. The inte~~e 37 would then modulate power to have the same effect as the geneId~,r 27 with temperature control. A microprocessor 38 in controlling ~elllp~d~ule operates over two stages. In the first stage, the baseline temperature is measured and then the slope or inten~1ed rise is calculated to achieve the target temperature in lO seconds. In the second stage, the temperature is held at the target for a second lO second period. In each stage, proportional 2 0 control is used to adjust power delivery from the generator 27. The power delivery from the generator 27 is controlled by a digital-to-analog co"ve-ler 37 from the microprocessor 38 to drive a voltage that is p-opo-lional to power from the RF generator 27.
Proportional control is implementeid as follows, where Tp = proportioning band (C) Pm = ~ power (W) T = measured temperature (C) T, = target or setpoint temperature (C) P = power level setting to regulate at the target temperature (W) If (T, - T) > O then P = Pm 3 0 otherwise if ~, - T) < O then P = O
otherwise P = Pm (T, - I~/Tp Proportional control can be implemented on the rise or heatup of the mucosa sensor 32 for temperature when elevated toward the target temperature. Proportional control can also be implemented to hold the temperature cors~l~ during stage two, the steady state part of the 3 5 activation.

CA 02204~66 1997-0~-06 ~l(e~dl~ly the RF ~~,.1c.d~or 27 would be electrically coupled to tbe two or more bipolar electrodes 29, 30 and 31 with the mucosa sensor 32 Illoni~o~ g with an i,l,~edallce r~l~ive circuit at 39 electrically coupled to the RF g~ tor 27 and sensitive to the Impeddflce betwveen the bipolar electrodes 29, 30 and 31 during the application of RF
energy. The impe(l~nre r~onsive circuit 39 would thus be in tbe electrical coupling b~n the RF ge~ (,r 27 and the two or more bipolar electrodes 29, 30, and 31. Theimpedance l~,onsive circuit 39 could receive voltages pf~ol~ional to RF voltage and current delivered so a calculator in the impedance responsive circuit 39 would find in real time the impedance delivered to the patient end. The impedance calculated in real time thus verifies initial electrode contact with the tissue and thereafter ,l,cas.l,es changes in mllcos~l layer impedance between the bipolar electrodes 29, 30 and 31 during theapplication of RF energy. The calculator includes a memory having an equation for the power delivery with respect to time and a co",~a,dor in the calculator to equate power delivered to power required by the equation for closed loop control of the power delivered over elapsed time thus shaping lesion spread and size. The equation in the memory controls power to a range of 5 to 15 watts to reduce sticking and charring to the electrodes in contact with the mucosa layer. Of course, the impedance circuit 39 could be within the generator 27 and the calculator would be written the microprocessor 38.
In an alle",a~e embodiment with three bipolar electrodes 29, 30 and 31 shown schem$ically in Figure 7, the bipolar electrodes 29, 30 and 31 are connected to RF
generator 27 that has switching in a multiplexer 40 shown in Figure 3 to deliver RF energy selectively between one pair of the bipolar electrodes 29, 30 and 31 or co",bindions thereof. Thereafter the delivery of RF energy between the various combinations of bipolar electrodes 29, 30 and 31 creates a plurality of lesions therebetween inside the mucosal layer 33 of the fallopian tubes 23 as illustrated in the various combinations shown in Figure 7.
Note that Figure 7 shows three lesion locations from application of dirrele"~ combinations of bipolar electrodes 29, 30 and 31. Con~eq~lPntly, the size and shape of the respective lesions 22 in each of the three views can be made to order. In the top view of Figure 7, bipolar electrodes 29 and 30 when activated produce a lesion 22 that begins in the middle 3 0 thereof between the bipolar electrodes 29 and 30. During second stage of energy delivery, the lesion 22 extends axially in the proximal and distal directions to enco"lpass the bipolar electrodes 29 and 30. Similarly, the centered view of Figure 7 has the bipolar electrodes 29 and 31 of the same relative polarity and bipolar electrode 30 is the opposite polarity. Thus, the lesion 22 extends from around bipolar electrode 30 to extend symmetrically to the other bipolar electrodes 29 and 31. The bottom view of Figure 7 has bipolar electrode 29 CA 02204~66 1997-0~-06 nf~l~ to have one polarity and bipolar electrodes 30 and 31 are the other polarity. The lesion 22 favors geGg~ hic?lly the space about bipolar electrode 29 and tbe gap between bipolar electrodes 29 and 30. Of course this could be shifted distally by reversing the respective polarity and collp!ing~.
The ~a~dlus 20 has the bipolar electrodes 29, 30 and 31 linearly arrayed to be activated in a bipolar fashion as described. Since there may be from two to eight cylindrical electrodes in an array, any combination of two, thtee, four, etc. electrodes may be chosen to activate. The multiplexer 40 can be used to time sequ~on~e the bipolar electrodes 29, 30 and 31 in pairs to provide a contiguous lesion 22 of 1 to 4 cm length. Each lesion can be entirely completed before proceeding to the next con~ d~ion of bipolar electrodes or they can be time multiplexed such that they are all heating sim~llt~neously. The one or more bipolar electrodes 29, 30 and 31 are spaced apart to create multiple separate lesions 22 inside the fallopian tube 23 without the need to axially relocate the placed catheter 21. The one or more bipolar electrodes 29, 30 or 31 are of dirfelel-l sizes so that when tissue contact is made the position near one of the bipolar electrodes 29, 30 or 31 is defined and the extent, depth and severity of the lesion 22 formation desired by the surgeon results.
The catheter 21 is flexible being made of a polymer such as polyethylene and includes a blunt tip at the patient end 24 to f~ t~te introduction into the fallopian tubes 23 and to avoid perforation thereof. Alle.l,alively, an introducer 41 with a performed bend 2 0 42, see Figure 6, could be placed with its opening 43 directed toward the tubal osteum. In this manner, the RF catheter 21 slides inside the introducer 41 until it enters the fallopian tubes 23. The progression of the catheter 21 entry into the fallopian tube 23 could be moniloled by transvaginal or abdominal ultrasound. The mucosa sensor 32 for temperature could be connected to RF generator 27 that has energy delivery control circuilry to regulate delivery of RF energy to a temperature range of about 95 C to 105 C between the bipolar electrodes 29, 30 or 31 as illustrated in Figures 2 and 3. The energy delivery control circuil.~ in Figures 2 and 3 includes a proportional controller in the microprocessor 38 for substantially regulating the RF energy delivery to control temperature rise time for lesion formation and to "-~inl~ the temperature near the mid point of a temperature range of 95 C
3 0 to 105 C during thermal necrosis of tissue for the llall;~lllUldl formation of lesion 22.
A hysteroscope 44 shown sch~m~tic~lly in Figure 5 could visualize the progression of the lesion 22 via video. A hysteroscope 44, made by Wolf Instruments Company located in Minneapolis, MN, can be used. That device has a mini~ture crescent shaped outer tube wall that contains imaging delivery and light delivery surrounding an operating channel.
3 5 The mucosa sensors 32 for temperature as shown in Figure 1 are located centrally relative CA 02204~66 l997-0~-06 to the axis "A" within the gap 34 between l~ C~ electrodes. The circular cross section of the catheter 21 can be solid with the t~lupe~dlule sensors located centrally of the solid circular cross section of the catheter 21 as seen in the cross section of Figure 8. The circular cross section of the catheter 21 might be hollow having inside and outside walls 45 and 46, see Figure 8, of the catheter 21. If a guide wire 47 is used instead of introducer 41 to aid in plq~emPnt~ it would be as shown in Figure 8. Such temperature sensor 32 is then located on the inside wall 45. The temperature sensors 32 qlle~ ively can be located on the outside wall 46 as in Figure 9. The le",~eldtu,e sensors 32 all~ a~ively can be located within the wall 48 as in Figure 11.
A method for transcervical sterilization with thermal energy delivery for creating lesions 22 in the fallopian tubes 23 with steps including transcervically inserting into fallopian tube 23 the catheter 21 elongate along its axis ~A" and the catheter 21 with its patient end 24. The catheter 21 is generally circular in cross section and sized for the fallopian tube 23. The step of delivering RF energy and monitoring the effect of RF
energy during delivery on the mucosa at the connector 25 on the end of the catheter 21 opposite the patient end 24 is included. Circumscribing the catheter 21 with two or more bipolar electrodes 29, 30 and 31 on the patient end 24 thereof so each of the electrodes is spaced from one another while passing RF energy between the two or more bipolar electrodes 29, 30 and 31 are steps of the method. The step of de~ g the condition of 2 0 the lrdl~llwldl for nation of lesion 22 between each of the electrodes with the mucosa sensor 32 located between the electrodes is followed during the application of RF energy.
The method step of transcervically inserting into fallopian tube 23 is performed by the surgeon manipulating during transcervical plq~em~nt and withdrawal the connector 25 shaped and located at the end opposite. The step of dele~...i--il-g the condition of the ~a~ uldl formation of lesion 22 between each of the electrodes in an q-lt~rnqte method includes measuring impedance change during delivery of RF energy. The step of d~e~ ini.~g the condition of the lral]SlllUldl formation of lesion 22 between each of the electrodes prefe~dbly includes measuring temperature change during delivery of RF energy.
The step of dele~...i-.il-g the condition of the l~dl~lllulal formation of lesion 22 between each of the electrodes includes controlling temperature of the mucosa during delivery of RF
energy to achieve temperature the range of about 95 C to 105 C in the mucosa. The step of controlling temperature of the mucosa during delivery of RF includes forming lesion 22 ~ub~ ially through the wall of the fallopian tube 23. The step of collapsing the lesioned surface of the fallopian tube 23 after withdrawal of the catheter 21 followed by adhering CA 02204566 l997-05-06 with a fibroid growth the cQll~sPA a~lioir~;~ surfaces during a period of three to ten days after withdrawal is plt;re àbly followed; this con~lition is illu~l,àled in Figure 12.
Another ~palaluS for transcervical stPrili7~tion with thermal energy delivery for creating lesions 22 in the fallopian tubes 23 has the ~'~ ga~e circular catheter 21 with its patient end 24 sized for transcervical insertion into the fallopian tube 23. One or more pie_oelectric tr~n.~ducPr~ 49 in Figure 14 are on the patient end 24 of the catheter 21. As illustrated in Figure 14, pie_oelectric tr~n~ducP~r 49 is a thermal energy source (e.g., C5800 or PZT8, Valpey-Fisher, Framington, MA) which lla~l~lS an acoustic wave that is absorbed by the adjacent tissue and is co"~t;,led to heat. Each pie~ll~sducer 49 is a thin cylinder circumscribing the catheter 21. The cylinder is coated on the inside and outside with a thin gold or gold/chloll,iu,l, coating to provide a cQn~ll-ctive surface as a palllwa~ to energize the opposing cylindrical faces with an AC voltage in the range of 3-12 MHz. The wall thickness determines the resonant frequency of the driving voltage. The cylinder is preferably located such that its inner cylinder wall rides on the catheter 21. The outside of the cylinder is coated with an in~ul~ting coating or is loosely placed inside of an insulator (i.e. polyethylene) that allows cooling fluid to be circulated around the cylinder surface.
This coolant reduces the surface l~",peldlule of the piezoelectric transducer 49, cools the tissue in contact with the device and provides acoustic coupling. In another embodiment, the PZT element is inside of the catheter 21 and thus acoustically beams through the catheter 21. Electrical leads from a driving generator supply energy to each pie~o~ ducer included to transfer electrical fluc*ln~ing energy from the driving generator to each piezotransducer 49. Each piezotr~n~ducer 49 is located to heat mucosa 33 tissue. The connector 25 on the end of the catheter 21 opposile the patient end 24 includes separable terminations for the electrical leads for piezoelectric energy and for monitoring. The connector 25 is shaped for the surgeon to manipulate during transcervical pl~PmPnt and withdrawal. The mucosa sensor 32 responds to applied thermal energy passing from the one or more piezotr~n~ducers 49 and deterTninP-s the condition of the lldnsmu~dl formation of a lesion 22 about the one or more piezotransducers 49. The one or more piezotransducers 49 are prere,dbly spaced axially from at least one adjacent piezotransducer 49. Although not shown, this is i~lçntis~l to alrdnge",ent of the bipolar electrodes 29, 30 and 31. The plel~lled tip is blunt and insulated to serve as a guide for the catheter 21.
The current method includes placement of the bipolar electrodes 29, 30 and 31 into the fallopian tube 23. Impedance and temperature are monitored to assure proper placement. Bl~n~hing of the fallopian tube 23 wall is visible through scope 44 as the tissue CA 02204~66 l997-0~-06 ~ 14 ~lesirc~es. The imaging catheter attaches to video to allow obse~ ~dlion of the lesion 22 and pl~cem~nt of the bipolar electrodes 29, 30 and 31.
P1~Gem~~-nt of the apl)drdlus during a rabbit study used the catheter that delivers the RF energy to lesion the fallopian tubes that was flexible and had a slight taper in the tip with a blunt and sealed end to .,.i.~ ;,e perforation. The transcervical entry was made either with a rigid or flexible hy~leloscope with an operating channel of 1-1.5 mm for passage of the electrode. Under direct vi~ i7~ti()n~ m~rking~ on the catheter at 10 mm intervals allowed the monitoring of insertion depth to place the lesion in the correct target zone which should be in the cornua or ampulla zone of the fallopian tube.
The bipolar RF electrodes placed into the fallopian tube with intimate contact with the mucosal layer blanches and constricts slightly upon heating the zone of mucosa between the electrodes. The level and rate of energy application reduces sticking of the electrode to the mucosa as well as charring. When sticking was excessive, the electrode did not easily remove. When excessive charring occurred due to high temperatures, the electrodes cause a tunnel and the normally closed tube remained open after the electrode removal. In the range of energy applied resulting in temperatures between 9S-105 C, the tube closes after removal of the electrodes and the catheter easily slid out. The depth of the lesion is 1-3 mm of the tubal wall eYten~ling outward from the inner lumen and falling off radially such that the outer wall will not become so hot as to harm nearby structures that may include bowel or other heat sensitive organs. Figure 12 shows the crossection of the fallopian tube. The inner mucosal surfaces are normally closed as shown in the figure. After the lesioning is performed, the mllcos~l walls will once again close together. The intended extent of the lesion is shown shaded in the figure.
The healing process ultimately closed the treated fallopian tube. The initial 2 5 response of the heating of the fallopian tube is an infl~ o~y response that then began to close the tube. ~ver time, the tissue fibroses and the lumen closes or is obliterated. Thus, no plug or foreign body is left in place in the lesion site. Because the lumen walls do not imme~i~tely adhere, removal of the catheter and electrodes is easy. Following the lesion creation, sufficient healing time of 2~ weeks is required to insure tubal closure. Complete 3 0 closure is necess~ry to avoid ectopic pregnancy. The quality of the lesion site may then be evaluated by one of the following methods: 1) an x-ray contrast material injected into the tubal osteum and eY~min~d by fluoroscopy, 2) a small laparoscope is placed abdominally or transvaginally into the abdomen to evaluate a colored dye injected into the tubal osteum and observed to exit from the fimbrial end of the tube, or 3) microbubble emulsions are injected CA 02204~66 1997-0~-06 into the tubes and color flow doppler or sOllogla~hy evaluales the extent of the flow down the tube.
Mini-pig study:
In a study of swine with 3 week healing, 105 C lesions were made at one or both ends of the fallopian tubes. The mucosa of the fallopian tube secrete fluid con~ uollsly and thus if both ends are sealed create a large fluid fl;~te-n~led zone called hydrosalpinx. In fallopian tubes with lesions on only one side, there was no h~dl()s~lpil~. In 8/11 tubes with lesions on both ends, hydrosalpinx was evident. In several of the fallopian tubes, the lumen was obliterated as seen in histological analysis.
Rabbit study:
In two mating studies of 70 rabbits, in activations where the bipolar electrodes delivered either 95 or 100 C to the mucosal layer of the fallopian tube, there were no pregn~ncies.
The healing period was 4 weeks or 3 months ffler lesioning and mating was daily for three weeks post-healing. The rabbit fallopian tubes are somewhat smaller in diAmeter than humans, although the lesions were llallsluu~àl with bl~nrhing on the outside of the structure imm~li~tely after lesioning. In humans with the larger fallopian tube, the lesions will be somewhat ~liminiched through the wall to the outer layers. The fallopian tubes of the rabbits were given a 95 C or 105 C thermal dose with a 10 second rise to the target temperature and then a further 10 second hold. The catheter was immPAi~tely removed from the fallopian tube. There was a single electrode failure where the target temperature was reached after 13 seconds and not well IllA;ll~ ed at steady-state. The uterine horn associated with this fallopian tube had 7 gestational sacs. In the Le~ g 19 fallopian tubes that were treated to 95 C according to protocol, there were no gestational sacs. In the 105 C series, there were no pregnAn~ies in the 20 uterine horns treated. There were 39 2 5 gestational sacs in the 8 control uterine horns.
~o~dul~ in l-.. ~.. c:
The device is used with transvaginal and transcervical access. The patient is premedicated with an oral sedative and the cervix is anesthetized with a paracervical block. If dilation is required, this would be done next to allow a CO2 hysteroscope to enter the cervix. The hysteroscope would have an operating channel of at least 1 mm and be either rigid or flexible. The hysteroscope is inserted into the cervix and advanced superiorly towards the fundus. The tubal osteum is then vic~ i7ed on either right or left side. Then the catheter electrode is advanced a fixed distance (marked on the catheter electrode) until it enters the tubal osteum and enters sufficiently to be placed into the cornual or isthmus region of the fallopian tubes. The CO2 in~ tor is turned off, then two or more electrodes are then CA 02204~66 l997-0~-06 attached to the output of the ge"e alor and the contact impedance read to assure viable tissue contact, especially if concern about tubal p~ alion is an issue. A le.ll~e~dtu,e sensor which could be a thermocouple, the~...i~tor or fibe.oplic probe is located in the catheter between the active electrodes. Power is applied at 500 kHz in two cycles. The target temperature is between 95 C and 105 C. The electrodes are then elle~ ed during cycle 1 which is 10 seconds in duration and power is controlled such that the t~ )eldlule of the sensor ramps linearly to the target temperature. In cycle 2, the power is adjusted such that the temperature remains constant over a 10 second cycle. Following this cycle, power is turned off and the temperature decrease is observed as well as impedance values to leas~.l,e that the electrodes are still in contact with the tissue inside the fallopian tube. The fallopian tube is a normally closed structure and the energy deposited and lesion created is such that the electrode does not stick to the tube as it is removed and that the tube then lm~S its normally closed resting state. Tn~ufflation is resumed. The other tubal osteum is then located, the electrode passed inside and the procedure repeated. As the coagulation process is underway, the hysteroscope allows observation of steam, smoke or popping of the tissue during the time power is applied. ~ltern~tely, if difficulty (such as resis~ ce) is encounlered during insertion of the catheter, a linear everting catheter sheath may be used to guide introduction and adv~nremrnt of the catheter electrode into the fallopian tube. A
third allel"ativ~ would be to consider an ultrasound-guided procedure with echogenic, 2 O precurved introducer catheters such as the Jansen Andersen insemination set (Cook Instruments). Although this is not feasible for all women due to anatomic variation, the procedure is possible about 75-90% of the time. ~deqll~te pl~rPment can be confirmed by abdominal ultrasound. Overall, this procedure can be done much more rapidly thanhysteroscopy, and cervical dilatation/anesthesia is not necessary.
2 5 For embolization of blood vessels, a transcatheter technique of non-surgical management to occlude affected arteries and prevent further bleeding is done. The vessels would first be imaged by arteriography, CT or MRI to track the cause of hemorrhage or the extent of the anomalous vessel with appropliate feeder vessels to target for occluding. A
percutaneous puncture is made and a steerable wire is inserted into the nearest vessel to allow access to the target embolization site. Using common over-the-wire techniques, the thermal embolization catheter as described for tubal ligation, but having an axial passage, is passed to the embolization site. Power is applied preferably with a bipolar configuration as described previously. Temperatures between 50 and 90 C are controllably reached to create an embolus. The catheter is withdrawn following the heating; thus, forming an autologous CA 02204~66 l997-0~-06 l11rOI11~US. Angiography is redone to check the vessel for leakage or patency. The patient can be IJ.oni~ied after the procedure with CT or MRI sc~rlning.
Any a~a.alus intern~lly placed within a vessel for treating it by controlled spaced apart energy delivery from a catheter to ablate, lesion or thrombose tissue about the catheter is the concept. A catheter elongate along an axis has a patient end and is generally circular in cross section and sized for insertion into and passage within the vessel. A connector on the end of the catheter opposite the patient end includes ~e~ ...i-.~l ;ons for l~ i-.g energy and for monilo,il g. The connector is shaped for the surgeon to manipulate during vessel pi~r~.."e.~l and withdrawal. Two or more spaced apart energy delivery members are on the patient end of the catheter. Each of the members is separated axially from another and each of the members circumscribes the catheter. A sensor responds to energy applied to the lining by passing between the two or more members. The sensor determines the amount of ablation or thrombosis or the condition of the formation of a lesion between each of the members. A source of energy electrically couples to the terminations for tr~n~mi~sion to the members as the sensor controls the amount of energy delivered to the tissue.
While particular preferred embodiments and methods have been illustrated and described the scope of protection sought is in the claims that follow.

Claims

1. Apparatus for transcervical sterilization, comprising:
a catheter (21) elongate along an exis thereof having a patient end (24), the catheter (21) being generally circular in cross section;
an RF-generator (27); and two or more bipolar electrodes (29, 30 and 31) on the patient end (24) of the catheter (21) for delivering RF-energy to surrounding tissue in an area between said two or more bipolar electrodes while being energised by said RF-generator, said two or more bipolar electrodes being axially spaced from one another and each of said two or more bipolor electrodes (29, 30 and 31) circumscribing said catheter (21);
characterized in that the apparatus is provided with a mucosa sensor (32) which detects a parameter which indicates a change in temperature of the surrounding tissue in said area between said two of more bipolar electrodes (29, 30 and 31).

2. Apparatus according to Claim 1, characterized in that a controlling means (36, 35, 38 and 39) is provided for controlling the energy delivered from said RF-generator (27) to said two or more bipolar electrodes (29, 30 and 31) on the basis of said detected parameter.

3. Apparatus according to Claim 1 or 2, characterized in that said mucosa sensor (32) is a temperature sensor positioned on the patient end (24) in the space (34) between said two or more bipolar electrodes (29, 30 and 31) for detecting a change of temperature of said tissue while said two or more bipolar electrodes (29, 30 and 31) are energised.

4. Apparatus according to Claim 2, characterized in that said mucosa sensor (32) is a phase detector (35) positioned in said RF-generator (27), said detector being connected to said RF-generator and said two or more bipolar electrodes (29, 30 and 31) and which determines as said parameter a reactance of said surrounding tissue in the area between said two of more bipolar electrodes (29, 30 and 31) for measuring the heating during the energising of said two or more bipolar electrodes (29, 30 and 31) as an indicator for the delivery of RF-energy, said controlling means comprising a calculator and a memory including an equation for the power delivery with respect to time as well as a comparator for comparing the power delivered to power required according to said equation for closed-loop-control of the power delivered over elapsed time to shape lesion spread and shape.

5. Apparatus according to Claim 1 or 2, characterized in that said mucosa sensor (32) is an impedance responsive circuit (39) positioned in the RF-generator (27) said circuit being in the electrical coupling between the RF-generator (27) and said two or more bipolar electrodes (29, 30 and 31) for determining voltage and current delivered, a calculator being provided in said impedance responsive circuit (39) for finding impedance delivered to the patient end (24), for finding initial electrode contact with the tissue and for measuring the change in said surrounding tissue during the application of RF-energy.

6. Apparatus according to any one of Claims 1 to 5, characterized in that three bipolar electrodes are connected via switching means (40) to said RF-generator (27), said switching means being designed to selectively connect two of said three electrodes with said RF-generator (27) to create a plurality of lesions in the surrounding tissue.

7. Apparatus according to Claim 1, characterized in that the mucosa sensor (32) is a temperature sensor which is arranged on the patient end (24) in the space (34) between said two or more bipolar electrodes (29, 30 and 31) for detecting a change in temperature of the tissue while said two or more bipolar electrodes are energised and which is connected to said RF-generator (27), said RF-generator (27) comprising an energy delivery control circuit for regulating the delivery to a range of about 95°C to 105°C and said energy delivery control circuit comprising a proportional controller to control temperature rise time for transmural formation of the lesion and to maintain the temperature during thermal necrosis of tissue for the transmural formation of the lesion near the mid point of said range.

8. Apparatus according to any one of Claims 2 to 6, characterized in that said catheter (21) has an axial passage for transcatheter embolization and said controlling means (36, 37, 38, 39) controls the energy delivery of said RF-generator (27) to said two or more bipolar electrodes (29, 30 and 31) to achieve a tissue temperature between said two or more bipolar electrodes (29, 30 and 31) in the range of about 50°C to 90°C.

9. Apparatus for transcervical sterilization, comprising:
a catheter (21) elongate along an axis thereof with a patient end (24), the catheter (21) being generally circular in cross section;
a connector (25) on the end of said catheter (21) opposite the patient end (24), the connector (25) including terminals (26) for RF-energy and for monitoring, said catheter (21) having a handgrip for manipulation by a surgeon; and two or more bipolar electrodes (29, 30 and 31) on the patient end (24) of the catheter (21) for delivering RF-energy to surrounding tissue in the area between said two or more bipolar electrodes (29, 30 and 31) while being energised, said electrodes being axially spaced from one another, each of said two or more bipolar electrodes (29, 30, and 31) circumscribing said catheter (21); characterized in that a temperature sensor (32) is provided between said two or more bipolar electrodes (29, 30 and 31) for detecting a change of temperature of said surrounding tissue in the area between said two or more bipolar electrodes (29, 30 and 31).

10. Apparatus according to Claim 9, characterized in that catheter (21) has an axial passage for transcatheter embolization.