AU783533B2

AU783533B2 - System for varicose vein treatment

Info

Publication number: AU783533B2
Application number: AU89644/01A
Authority: AU
Inventors: Antonio Longo; Mark Neurohr
Original assignee: Ethicon Endo Surgery Europe GmbH
Current assignee: Ethicon Endo Surgery Europe GmbH
Priority date: 2000-08-30
Filing date: 2001-07-11
Publication date: 2005-11-03
Anticipated expiration: 2021-07-11
Also published as: EP1263340A1; CA2388096A1; DE10042493A1; JP4818566B2; WO2002017805A1; JP2004507315A; AU8964401A

Description

WO 02/17805 PCT[EP01/08016 1 System for varicose vein treatment The invention relates to a system for the application of thermal energy in order to cause permanent contraction of vascular structures, which can be used in, the treatment of varicose veins.

A current well-established treatment method for varicose vein pathology is stripping of the saphenous vein, see, L.

Jones et al., "Neovascularisation is the principal cause of varicose vein recurrence: results of a randomised trial of stripping the long saphenous vein", Eur J Vasc Endovasc Surg 12, 442-445 (1996); G. Goren, A.E. Yellin, "Minimally invasive surgery for primary varicose veins: limited invaginated axial stripping and tributary (hook) stab avulsion", Ann Vase Surg 9 401-414 (1995); P.H. Rutgers, P.J. Kitslaar, "Randomized trial for stripping versus high ligation combined with sclerotherapy in the treatment of the incompetent greater saphenous vein", Am J Surg 168, 311-315 (1994); S. Sarin et.

al., "Stripping of the long saphenous vein in the treatment of primary varicose veins", Br J Surg 81, 1455-1458 (1994).

WO 02/17805 PCT/EP01/08016 2 Incisions are made at the ankle and in the groin of the patient.

The saphenous vein is identified, ligated and divided. A flexible stripper is inserted into the saphenous vein at the ankle incision and passed through the vein in the proximal direction until it is exposed through the groin incision. A large end piece is attached to the stripper at its distal end; some strippers are designed with a built-in "olive"-shaped distal end. The saphenous vein is, in turn, tied to the distal end of the stripper and is then removed by quickly pulling the stripper through the groin incision.

This surgical technique eliminates the path of reflux and source of blood for the varicosities. However, it achieves this with great morbidity. The stripping procedure tears the saphenous vein from the collateral vessels and, in addition, the large end piece and the accumulating stripped portion of the saphenous vein create a large residual, subcutaneous channel within the leg after vein removal. These factors lead to bleeding and haematoma within the leg, a painful and slow healing condition resulting in lengthy convalescence. This trauma also leads to damage to the nerves near to the saphenous vein. In addition, the cosmetic results of this surgery are poor due to swelling, bruising, and discoloration.

Other clinical techniques have been developed to treat varicose veins while attempting to limit the morbidity associated with stripping. Ligation of the saphenous vein at the femoral vein junction Jones et al., "Neovascularisation is the principal cause of varicose vein recurrence: results of a randomised trial of stripping the long saphenous vein", Eur J Vasc Endovasc Surg 12, 442-445 (1996); S. Sarin et. al., "Stripping of the long saphenous vein in the treatment of primary varicose veins", Br J Surg 81, 1455-1458 (1994)) and compression sclerotherapy (K.

Biegeleisen, R.D. Nielsen, "Failure of angioscopically guided sclerotherapy to permanently obliterate greater saphenous varicosity", Phlebology 9, 21-24 (1994); G. Goren, "Injection WO 02/17805 PCT/EP01/08016 3 sclerotherapy for varicose veins: History and effectiveness", Phlebology 6, 7-11 (1991); P.H. Rutgers, P.J. Kitslaar, "Randomized trial for stripping versus high ligation combined with sclerotherapy in the treatment of the incompetent greater saphenous vein", Am J Surg 168, 311-315 (1994)) are two alternative varicose vein treatments. The goal of saphenous vein ligation at the femoral junction is to eliminate the major path of reflux into the saphenous vein. The procedure is carried out through a groin incision. The sapheno-femoral junction and all other local saphenous vein tributaries are identified, isolated, ligated and divided. With compression sclerotherapy, a sclerotising agent is injected into the diseased vein to be treated. The agent acts as an irritant, causing damage to the endothelial lining and edema of -the vessel wall. Compression bandaging is applied as an integral part of the treatment regimen. The external force presses the damaged endothelial layers of the vessel together. Over time, the vessel walls weld together due to fibrosis and the vessel is occluded. However, both methods described above have high clinical recurrence rates and are not considered to be optimum treatment methods.

Therefore, less invasive and less traumatic methods of treating varicose pathologies were investigated. Generally, the use of intraluminal energy to constrict, damage and occlude vessels is known in the art Gorisch et al., "Heat-induced contraction of blood vessels", Lasers Surg Med 1-13 (1982); G.T. Watt, "Endovenous diathermy destruction of internal saphenous", British Medical Journal, 53 (Oct. 7, 1972); K. O'Reilly, "Endovenous dia-thermy sclerosis of varicose veins", The Australian, New Zealand Journal of Surgery 47 (No. 393-395 (June 1977); Cragg, et al. "Endovascular diathermic vessel occlusion", Diagnostic Radiology 144, 303-308 (July 1982)).

US 6,014,589, WO 99/03413, and WO 99/12489 disclose a method and a device to treat varicose veins by causing the permanent closure of the saphenous vein by the intraluminal application of 004648733 4 radio frequency (RF) energy. The energy causes vessel contraction and eventual occlusion. The energy is applied via a catheter with an expandable electrode tip. This method has the advantage of being less traumatic than the vein stripping. However, the major disadvantage is the cost and complexity of the catheter treatment system. The challenge of this design is that the catheter must be small enough to be introduced into the saphenous vein while, at the same time, having the ability to treat large diameter vessels. This is accomplished with an expandable electrode array at the catheter tip. A disadvantage is the use of many small, movable components, which is expensive and tends to be less reliable. Moreover, the use of small electrodes interacting with blood within the vessel lumen also leads to fouling of the treatment tip.

Another method and device for permanent vessel occlusion involving various means of mechanically collapsing the vessel and applying energy is known from US 5,709,224 and WO96/39961. Body lumens such as blood vessels are selectively occluded by mechanically collapsing the blood vessel, e. g. by using a negative pressure, and subsequently applying RF energy via one or more electrodes within or adjacent the collapsed region.

US 5,273,524 discloses an endoscopic instrument with an electrosurgical end-effector.

The primary function is tissue ablation with a mono-polar radio frequency electrode positioned at the distal tip of the instrument. A secondary function of tissue removal is 20 accomplished by serial fluid irrigation and suction of the surgical site. The device design S: includes a handle with a rigid metallic tube. The tube structure incorporates the coo treatment electrode at its distal end along with a single suction/irrigation lumen within S. the tube.

The foregoing prior art discussion is not to be taken as an admission of common general knowledge.

The object of at least the preferred embodiment of the present invention is to provide a possibility to cause permanent contraction of vascular structures, which is efficient, costeffective, and less troublesome to the patient.

004648733 In accordance with the invention, there is provided a system for the application of thermal energy in order to cause permanent contraction of vascular structures having the features of claim 1. Advantageous versions of the invention follow from the dependent claims.

The system according to the invention for the application of thermal energy in order to cause permanent contraction of vascular structures comprises a catheter, which is introduceable into a vascular structure and comprises at least one lumen having an opening in the distal end region. Another component of the system is a control device, to which the catheter is connectable via its proximal end region. The control device is adapted to provide a liquid, to cause heating of the liquid to a preselected temperature and to supply the heated liquid into a lumen of the catheter and to apply a vacuum to a lumen of the catheter. The preselected temperature is sufficiently high for causing permanent contraction of vascular structures when the liquid leaves the lumen at the opening of the lumen in the distal and region of the catheter. Additionally, an electric ::15 heater for heating the liquid can be arranged in the distal end region of the catheter; in that case the control device is adapted to control this heater too.

The present invention achieves the clinical objective of contracting or occluding a vessel, e. g. the saphenous vein, by intraluminal application of heat energy. The heat is transferred to the vascular structure in question via a heated liquid, preferably a 20 physiological treatment fluid. This concept allows for a simplified, less expensive, and S: more robust design of the components of the system, in particular of the catheter.

~The system has the advantage that the catheter can be designed as a disposable component adapted to deliver and return the heat transfer liquid to a local treatment area within the lumen of a WO 02/17805 PCT/EPOI/08016 -6vessel. The complexity and expense of the system is moved from the catheter to the control device. Preferably, the control device is a reusable device designed to be used outside the sterile surgical field. It preferably contains all or most of the components and control units for heating, delivery and return of the liquid.

The procedure in which the system according to the invention is used is similar to the current procedures, but offers many advantages. The catheter is inserted into the vessel to be treated and passed to the end of the treatment section. The blood can be evacuated from the vessel to be treated by such methods as elevation, roller cuff, compression bandaging or direct application of pressure. -Then the system is activated. The liquid-.sent-to) the treatment site through the catheter is heated, fills the treatment area and homogenously treats, i.e. heats, the vessel wall. The liquid is then returned, by means of a vacuum, via the catheter, preferably to a collection container located in or connected to the control device. This treatment cycle continues as the-catheter is retracted from the vessel, thus treating a length of the vessel.

The system according to the invention permits less invasive and less traumatic treatment than current methods, eliminating haematomas, swelling, and bruising and reducing pain and time associated with recovery. The treatment time is comparable to that of current methods. An efficient catheter design allows for lower costs such that the catheter can be provided as a disposable article. Moreover, the use of a heated liquid or physiological treatment fluid allows for a homogenous and uniform treatment of the vessel wall, which avoids the application of excessive heat to certain spots and generally allows for shorter treatment times, thus reducing thermal effects upon surrounding structures.

WO 02/17805 PCT/EP01/08016 -7- The physiological treatment fluid is preferably saline solution.

It may also contain typical sclerotising agents to aid the treatment of the vessel.

In an advantageous version of the invention, the catheter comprises at least two lumina, each having an opening in the distal end region, and the catheter and the control device are adapted to supply the liquid and to apply the vacuum to separate lumina.

Preferably, one lumen runs in the inner region of the catheter, such lumen being adapted to supply the liquid. In this case, the catheter can have a generally circular cross-sectional shape and a coaxial arrangement of the lumina, the lumen for supplying the liquid running generally along the central axis of the catheter.

This arrangement has many-advantages, -in particular if the liquid is heated by the control device. First, it is an efficient arrangement within a prescribed outer envelope that allows for a maximum cross-section of the lumen for improved delivery and return flows. Second, this arrangement is thermally efficient.

Heat loss along the length of the catheter is reduced because the central lumen for liquid supply is insulated by two wall thicknesses of catheter material and by the return lumen or return lumina (to which the vacuum is applied). Heat loss is also reduced because the heat transfer interface of the liquid delivered to the treatment site is minimized to the diameter of the central lumen. In this way, the temperature loss of the liquid delivered to the distal end region of the catheter is minimized, whereas the catheter maintains a lower temperature on the outer surface along its length where it comes into contact with the vessel wall. This avoids unintentional thermal treatment of the vessel before the controlled treatment at the catheter tip, i.e. in its distal end region.

If the catheter comprises at least two lumina, the distal end region of the catheter preferably has at least one supply port and at least one vacuum port. These ports can be designed for WO 02/17805 PCT/EPO1/08016 8optimum delivery and removal of the liquid, as illustrated below by means of specific embodiments.

Moreover, if the catheter comprises at least two lumina, the control device can be adapted to supply liquid and to apply a vacuum to respective separate lumina of the catheter simultaneously. In this way, heated liquid is delivered to the vessel wall at the treatment site, and at the same time used liquid is aspirated, thus enabling a steady flow and uniform and welldefined treatment conditions.

In an alternative embodiment of the invention, the catheter has one lumen only and the control device is adapted to supply lii quid-to .the lumen- o*f the catheter and to apply a vacuum to -thelumen of the catheter alternately. In this case, the design of the catheter is particularly simple, but during the heat treatment a steady flow of the liquid is not possible. The latter is not a disadvantage, however, e.g. if a vessel is sectionally treated along its length. To this end, a given section of a vessel wall can be heated by means of a certain amount of liquid for a certain period. Then this liquid is aspirated, and the catheter is retracted in order to expose the next section of the vessel wall to be treated, etc.

Preferably, the catheter has an atraumatically shaped distal end region. Moreover, the catheter can be adapted to be inserted into a vascular structure by means of a guidewire. To this end, the guide wire can be guided in one of the lumina considered above or in an extra lumen provided for the guidewire.

As already mentioned, the control device is preferably adapted to heat the liquid to a preselected temperature and to supply the heated liquid to a lumen of the catheter. In this case, the design of the catheter can be particularly simple because it does not include a heater.

004648733 9 It is also possible to arrange an additional electric heater, which is preferably designed as a resistive heater, for heating the liquid in the distal end region of the catheter, wherein the control device is adapted to control this heater. This concept still allows for a uniform heat transfer from the heat source to the vessel wall when the liquid supplied by the control device flows around the electric heater and is heated in this way, whereas the electric heater does not directly contact the vessel wall. Preferably, a temperature sensor, which is electrically connected to the control device, is located in the proximity of the electric heater in order to monitor the temperature of the liquid and to aid in controlling the heater. The electric heater can be used for fine-adjustment of the temperature of a liquid which is preheated by the control device. It is advantageous that the electric heater can allow for a better fine-control of the temperature of the liquid, but on the other hand a catheter including an electric heater contains a larger number of components and is more expensive.

As already mentioned, the control device is preferably designed as a reusable component to be used outside the sterile field. It preferably includes an electrical supply for the entire system, a standard connection for supply of the liquid (treatment fluid) and/or optionally a reservoir for fresh liquid, a pump for supplying the liquid to the catheter, optionally a heater to heat the liquid, a vacuum pump for applying the vacuum S and aspirate the spent liquid, optionally a reservoir to collect the spent liquid, a connection fitting for the catheter (which preferably is provided with an integral connector at its proximal end for quick connection to the connection fitting of the control device) and all sensors and controls to operate the system.

oleo In accordance with a second aspect of the invention, there is provided a method of applying thermal energy in order to cause permanent contraction of vascular structures, the method comprising introducing a catheter into a vascular structure, said catheter comprising at least one lumen having an opening in the distal end region; heating liquid to a preselected temperature remotely of the distal end region; supplying the heated liquid into a lumen of the catheter; and 004648733 9a applying a vacuum to a lumen of the catheter, wherein the preselected temperature is sufficiently high for causing permanent contraction of vascular structures when the liquid leaves the lumen at the opening of the lumen in the distal end region of the catheter.

As used herein, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude other additives, components, integers or steps.

S *l *o• WO 02/17805 PCT/EP01/08016 10 In the following, the invention is explained in more detail by means of embodiments. The drawings show in Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 a view of an embodiment of the system according to the invention, comprising a control device and a catheter connected to the control device, a schematic illustration of the use of the system in order to cause permanent contraction of vascular structures, i.e. in part the catheter being introduced into a"vessel before the application of thermal energy and in part after the application of thermal energy, the vessel being contracted, in part a side view of the distal portion of the catheter of Figure 1 and in part a longitudinal section of the distal portion of this catheter, in part a cross-section of the catheter of Figure 3 along the line III-III of Figure 3 in part (b) a similar cross-section of a second embodiment of the catheter, and in part a similar cross-section of a third embodiment of the catheter, in part a side view of the distal portion of a fourth embodiment of the catheter, in part a longitudinal section of this embodiment along the axis V-V of part and in part an end view of this embodiment, and in part a side view of the distal portion of a fifth embodiment of the catheter, in part a longitudinal section of this embodiment along the axis VI-VI of part and in part an end view of this embodiment.

Figure 6 WO 02/17805 PCT[EP01/08016 11 Figure 1 illustrates an embodiment of the system for the application of thermal energy in order to cause permanent contraction of vascular structures. The system comprises a catheter 1 and a control device 2. The catheter 1 is introduceable into a vascular structure, e.g. the saphenous vein or another vein, via its distal end 4. At its proximal end 5, the catheter 1 includes an integral connector 6 which fits to a port provided at the control device 2.

The primary function of the catheter 1 is to deliver a physiological fluid (which, in the embodiment, is heated by the control device 2) to a treatment site in the vascular structure where the catheter 1 has been inserted and to return the used physiological -fluid from the treatment site. To this end, the -catheter 1 comprises at least one lumen having an opening in the region of its distal end 4. The catheter 1 must be able to be easily inserted into and then guided within the lumen of the vascular structure or vessel to the initial treatment site. It can be constructed of a biocompatible polymer such as polytetrafluoroethylene (PTFE), polyurethane, polyethylene, *or polyvinylchloride. The catheter 1 is preferably constructed of PTFE. PTFE offers the advantages of biocompatibility, chemical inertness, dimensional stability, thermal insulation, and a smooth surface finish. Specifically dealing with insertion and guiding, the catheter must be of the proper stiffness. This can be accomplished with an appropriate balance of material properties and lumen dimensions or a design that allows for the use of a guidewire through a lumen. Preferably, the tip or distal end region of the catheter is of ergonomic design to allow easy insertion.

In order to be inserted into the vessel to be treated, the outside diameter of the catheter 1 should be in the range from 1 mm to 5 mm, preferably around 3 mm. For treatment of long vessels within the body of a patient, the catheter 1 should have a length from 50 cm to 150 cm, preferably around 100 cm.

WO 02/17805 PCT/EP01/08016 12 In the embodiment, the control device 2 includes a standard connection to a separate container for the physiological treatment fluid and an electrical pump for delivering the physiological fluid from this container to a lumen of the catheter 1. In the control device 2, the physiological fluid is heated to a preselected temperature before it is supplied to the catheter 1.

Moreover, the control device 2 comprises a vacuum pump for applying a vacuum to a lumen of the catheter. By means of this vacuum, spent treatment fluid is collected and fed to a reservoir, which is located outside the control device 2. The control device 2 also includes the electrical supplies, sensors, and control means (preferably comprising a microprocessor) to operate the system.

Figure 2 illustrates the concept of use of the system. In Figure 2(a) the distal end 4 of catheter 1 has been guided inside the lumen of a vessel 8 to a predetermined position, i.e. the treatment site where the vessel 8 is to be contracted, for varicose vein treatment. In this position of the catheter 1, the control device 2 is operated to deliver heated physiological fluid via the catheter 1 to the .treatment site, where the physiological fluid leaves the lumen of the catheter 1 and heats the wall of the vessel 8. This causes a contraction of the wall, resulting in a contracted area 9. Preferably, the temperature of the physiological fluid is about 800 C to 900 C when it leaves the catheter 1. The spent physiological fluid is aspirated via the catheter 1, together with any other liquids or solid particles at the treatment site (like blood, emboli, etc.), by means of the vacuum applied to the catheter 1.

In the embodiment, the catheter 1 has two lumina. The physiological fluid is supplied via one lumen while the vacuum is applied to the other lumen at the same time. This permits a continuous operation of the system, and the catheter 1 can be slowly pulled to the left (in the representation according to WO 02/17805 PCT/EP01/08016 13 Figure in order to cause a contraction of the vessel 8 along some section.

Alternatively, the delivery of the physiological fluid is interrupted after a certain amount has been supplied, whereupon the spent physiological fluid is aspirated. Thereafter, the catheter 1 is moved to the left (in the representation according to Figure for a preselected distance, and then another amount of heated physiological fluid is supplied, and so on.

Preferably, the physiological treatment fluid is a saline solution. It may also contain typical sclerotising agents to aid the treatment of the vessel. Usually, the contraction induced by the Sheat treatment is permanent. Figure 3 shows the catheter 1 in more detail. The catheter l includes a cylindrical exterior wall 10 and a cylindrical interior wall 12 in a coaxial arrangement., see also Figure 4(a) which shows a cross-section through catheter 1 along the line III-III of Figure 3 The interior wall 12 can be supported at the exterior wall 10 by some open structure which is not shown in the figures. The interior wall 12 defines the perimeter of a first lumen 14, which runs along the central axis of the catheter 1 and has an opening at the distal end 4 of catheter 1, which is designated as supply port 15. The annular space between the exterior wall 10 and the interior wall 12 defines a second lumen 16, which also has an opening at the distal end 4 of catheter 1, designated as suction port 17.

The heated physiological treatment fluid is supplied via the first lumen 14 and through the supply port 15, while the spent physiological treatment fluid is aspirated through the suction port 17 and returned via the second lumen 16, as indicated by the arrows in Figure 3 The coaxial arrangement of the lumina 14 and 16 has the advantage that the heated physiological treatment fluid does not contact the exterior wall 10 and thus cannot WO 02/17805 PCT/EP01/08016 14 cause undesired heat effects before the fluid leaves the catheter 1 at the supply port Figure 4(b) and Figure 4(c) show the cross-sectional shapes of two other embodiments of the catheter. In Figure a catheter 1' has a cylindrical exterior wall 10', which is divided by an inner wall 12' extending along the diameter of the catheter thus defining a first lumen 14' and a second lumen 16'.

In Figure a catheter 1" comprises a cylindrical exterior wall 10" and a star-like interior wall 12" which define three lumina 14", 16" and 18". The lumen 18", can be used for a guidewire and/or for the leads of a temperature sensor located .at the distal end of the catheter 1"-in order to monitor and control the temperature of the physiological treatment fluid delivered via the supply port.

Figure 5 illustrates the distal part of a fourth embodiment of the catheter, here designated by 20. The distal end region 21 is frustoconically shaped. The catheter 20 comprises an exterior wall 22 and an interior wall 23, which are coaxially arranged so that the cross-section looks like in Figure The interior wall 23 defines a first lumen 24 which ends at the supply port at the distal end of the catheter 20. The annular space between the exterior wall 22 and the interior wall 23 forms a second lumen 26, which has a total of four openings in the distal end region 21, i.e. four suction ports 27, which is best seen in the end view according to Figure This design allows for a particular efficient aspiration of spent physiological treatment fluid.

The distal portion of a fifth embodiment of the catheter, here designated by 30, is illustrated in Figure 6. Again, the distal end region 31 is frustoconical and thus has an ergonomic and atraumatic shape. The catheter 30 comprises a cylindrical WO 02/17805 PCT/EP01/08016 15 exterior wall 32 and a cylindrical interior wall 33, which are coaxially arranged, resulting in a cross-sectional shape as in Figure The interior wall 33 defines a first lumen 34, which is connected to the inner space of a cross tube 35 located close to the distal end of the interior wall 33, see Figure At both of its ends, the cross tube 35 extends to the exterior wall 32 and has openings, i.e. the supply ports 36.

Thus, physiological treatment fluid can be delivered via the first lumen 34 and through the supply ports 36 to the sides of the catheter 30, which enables a particularly efficient heat treatment.

A second lumen 38 ends at a suction port 39 at the distal end of catheter 30 and is used., to .aspirate the spent. physiological treatment fluid.

Claims

1. A vascular structure thermal energy application system to cause permanent contraction of vascular structures, comprising: a catheter, which is introduceable into a vascular structure and comprises at least one lumen having an opening in the distal end region, and a control device, to which the catheter is connectable via its proximal end region, the control device including a heater remote from the distal end region wherein the control device is operable to control the heater to cause heating of liquid to a preselected temperature, the control device being adaptedAsupply the heated liquid into the at least one lumen of the catheter through the opening in the distal end region and to apply a vacuum to a lumen of the catheter, wherein the preselected temperature is sufficiently high for causing permanent contraction of vascular structures when the liquid leaves the lumen at the opening in the distal end region of the catheter.

2. System according to claim 1, characterized in that the catheter comprises at least two lumina each having an opening in the distal end region and that the catheter and 0 the control device are adapted to supply the liquid and to apply the vacuum to separate .0oo 00:.0 lumina.

3. System according to claim 2, characterized in that one lumen runs in the inner region of the catheter such lumen being adapted to supply the liquid.

4. System according to claim 3, characterized in that the catheter has a generally circular cross-sectional shape and a coaxial arrangement of the lumina, the lumen for supplying the liquid running generally along the central axis of the catheter.

5. System according to any one of claims 2 to 4, characterized in that the distal end region of the catheter comprises at least one supply port and at least one vacuum port. 004648733 17

6. System according to any one of claims 2 to 5, characterized in that the control device is adapted to supply liquid and to apply a vacuum to respective separate lumina of the catheter simultaneously.

7. System according to claim 1, characterized in that the catheter has one lumen only and the control device is adapted to supply liquid to the lumen of the catheter and to apply a vacuum to the lumen of the catheter alternately.

8. System according to any one of claims 1 to 7, characterized in that the catheter has an atraumatically shaped distal end region.

9. System according to any one of claims 1 to 8, characterized in that the catheter is adapted to be inserted into a vascular structure by means of a guidewire.

System according to any one of claims 1 to 9, characterized in that the control device includes a pump for supplying the liquid.

11. System according to any one of claims 1 to 10, characterized in that the control device includes a vacuum pump for applying the vacuum.

12. System according to any one of claims 1 to 11, wherein the heater is an electric heater located within the control device.

13. System according to claim 12, characterized in that the electric heater is designed as a resistive heater.

14. A system for the application of thermal energy substantially as hereinbefore 20 described with reference to any one of the embodiments shown in the drawings.

15. A method of applying thermal energy in order to cause permanent contraction of vascular structures, the method comprising: introducing a catheter into a vascular structure, said catheter comprising at least one lumen having an opening in the distal end region; 004648733 18 heating liquid to a preselected temperature remotely of the distal end region; supplying the heated liquid into a lumen of the catheter; and applying a vacuum to a lumen of the catheter, wherein the preselected temperature is sufficiently high for causing permanent contraction of vascular structures when the liquid leaves the lumen at the opening of the lumen in the distal end region of the catheter.

16. The method of claim 15 wherein the catheter has two lumina, each having an opening in the distal end region, for liquid supply and vacuum respectively.

17. The method of claim 16 wherein the supply of liquid and application of vacuum occur at the same time.

18. The method of claim 17 wherein the catheter is moved continuously along a section of the vascular structure.

19. The method of claim 15 or 16 wherein fluid is supplied and vacuum is applied in successive steps.

20. The method of claim 19 wherein the catheter is moved after each vacuum step.

21. The method substantially as hereinbefore described with reference to the S: accompanying figures. Dated 2 August 2005 o Freehills Patent Trade Mark Attorneys 0-0020 Patent Attorneys for the Applicant: ooo Ethicon Endo-Surgery (Europe) GmbH