WO2014195491A1

WO2014195491A1 - An apparatus for thermal ablation

Info

Publication number: WO2014195491A1
Application number: PCT/EP2014/061895
Authority: WO
Inventors: Henrik Bisgaard Poulsen; Jacob Kollerup Jensen
Original assignee: Kebomed Ag
Priority date: 2013-06-07
Filing date: 2014-06-06
Publication date: 2014-12-11

Abstract

An apparatus for treating uterine disorders by effecting necrosis of the uterine endometrium. The apparatus comprises a catheter with a bladder which can be inflated with a hot medium controlled by a control means. To enable abortion of the treatment, the apparatus comprises an emergency release structure which can be activated independent on the control means to reduce pressure in the bladder.

Description

AN APPARATUS FOR THERMAL ABLATION

FIELD OF THE INVENTION

The invention relates to an apparatus for thermal ablation at a site in a subject. Particularly, the invention relates to an apparatus for treating uterine disorders by effecting necrosis of a uterine endometrium by use of a distendable balloon which is inserted into the uterus.

DESCRIPTION OF RELATED ART

Application of thermal energy is known for treating body tissues. Particularly, it is well known to effect necrosis of the endometrium e.g. by use of an expandable balloon or bladder filled with a fluid at an elevated temperature, typically about 80-90° Celsius. In an unexpended state, the balloon is inserted into uterus of the subject and hot fluid is displaced into the balloon which thereby expands. Close contact between the hot outer surface of the balloon and the tissue lining for which necrosis is desired is maintained typically for 8-15 minutes after which the fluid is drained from the balloon. The collapsed balloon can finally be removed from the subject. In some devices, the fluid is preheated outside the body, and then displaced into the balloon. In another type of device, the balloon houses a heater which can heat the fluid once it is inside the balloon.

The heating of the fluid and the displacement into and out of the balloon require monitoring by the medical practitioner. If the balloon is filled too much, too fast, or with a fluid which is too hot, it may have detrimental effect on the subject.

SUMMARY OF THE INVENTION

It is an object of embodiments of the invention to improve the existing methods and devices for conducting thermal ablation and particularly to provide a more simple and reliable apparatus, and potentially to reduce manufacturing costs. According to a first aspect, the invention provides an apparatus for treating uterine disorders by effecting necrosis of a uterine endometrium, the apparatus comprising :

• a catheter having a proximal end and a distal end;

• a bladder attached to the proximal end for insertion into uterus and being distendable upon introduction of an inflation medium;

• inflation means connected to said distal end for introducing the inflation medium into the bladder;

• heating means for heating the inflation medium to a temperature sufficient to effect tissue necrosis; and · control means communicating with the inflation means for controlling the inflation of the bladder.

According to the invention, the apparatus comprises an emergency release structure which can be activated independent on the control means to reduce pressure in the bladder.

Since the emergency release structure can be activated independent on the control means, pressure in the bladder can be reduced even if the control means or inflation means malfunction, and it can be activated at any time during the treatment - irrespective of the state of the control means or the progress of the treatment. When the pressure in the bladder is reduced, it can be removed from the patient.

As it appears from claim 1, the following definitions apply herein. Proximal end is defined as that end where the bladder is attached, i.e. the end pointing towards the patient during treatment. The distal end is the opposite end pointing away from the patient. Likewise, the proximal direction is the direction towards the patient and distal direction is the direction away from the patient during treatment.

The apparatus could be electrically operated such that distension and heating are caused by power driven inflation and heating means.

Particularly, the inflation means and the control means may be electrically operated while the emergency release structure is manually and non-electrically operated. This allows deflation of the bladder even when no electrical power is available, e.g. in case of malfunction in the electrical system or in the electrical supply.

The emergency release structure may e.g. form a manually operable emergency valve structure arranged to control a flow of the inflation medium into a disposal storage or simply out of the apparatus. The emergency release structure may particularly be completely independent on electrical power, i.e. completely non-electrically operated. It may e.g. consist of an emergency valve having a valve element which can be moved to thereby open the valve.

The activation of the emergency release structure may be caused via activation means arranged outside the apparatus. As an example, the movement of the emergency valve could be triggered by a push button or a pull tab or string or other pure mechanically interacting means arranged externally on the apparatus for easy access without having to open the apparatus or interfere with any other elements in the apparatus.

The catheter, the bladder, the inflation means, the heating means, and the control means could be joined inseparably to form integral parts of a mobile unit.

By mobile unit is herein meant a unit which does not need external power, and that the unit does not need other external resources. It may e.g. contain the inflation medium and electrical power, e.g. in a battery or similar internally contained power source. Further, it may have a size, shape, and weight enabling it to be manipulated as a one-piece device and by hand.

In one end, the mobile unit may form a handle suitable for manipulation of the unit by hand. In the opposite end, the mobile unit may be represented by the catheter and bladder.

The disposal storage may particularly form an integral part of the mobile unit, and it may contain an absorbing material, e.g. a body of a hydrophilic material, e.g. a polymer hydrophilic material, or similar absorbing material, such that the inflation medium is absorbed and the risk of spilling is minimized.

It may be desirable, once the emergency release structure is activated, to ensure that the apparatus is discharged without being used further.

As mentioned, the emergency release structure may particularly be activated by an activation structure in the form of a pull tab, a push button, or similar kind of switching control located on an external surface of the apparatus. Activation of the release structure may preferably be visually detectable. In one example, the pull tab is attached to an outer surface of the apparatus, e.g. adhesively, e.g. by use of tape or a sticker. Upon pulling in the pull tab, it may become released from the surface, e.g. during destruction of the tape or sticker, and the activation is therefore clearly detectable.

The apparatus may be connected to electrical power via a connection which disconnects upon activation of the emergency release structure. This may prevent use of the apparatus once an emergency situation has been detected, and it may prevent powering of the device in case of faults in the apparatus. In one embodiment, the control means is configured to determine activation of the emergency release structure. For that purpose, the apparatus may include an electrical switch structure which is operated as an integral part of the activation of the emergency release structure.

The activation of the emergency release structure could e.g. be determined by the control means by detection of a pressure drop, or it could be detected by having an electrical or mechanical sensor connected to the release structure. In one embodiment, the

aforementioned pull tab or similar kind of switching control located on an external surface of the apparatus not only opens the emergency valve, but also pulls a dip switch or other electrical components out of an electrical circuit and thereby disables further use of the apparatus.

Activation of the emergency release structure may e.g. prevent subsequent increase of pressure in the bladder. This may be achieved by disabling the inflation means such that it no longer can introduce the inflation medium into the bladder.

The emergency release structure may also be made such that it can only be activated, and such that, once being activated, it can't be de-activated. By way of example, the

aforementioned emergency valve structure may e.g. be operable from a closed position to an open position, but not reversible to the closed position. I.e. once opened, the inflation medium will drain out of the bladder and the emergency valve will remain open whereby the apparatus becomes unsuitable for further use. The aforementioned pull tab or similar kind of switching control located on an external surface of the apparatus may e.g. pull a valve element out of a valve housing whereby the valve opens. In one embodiment, the pull tab itself seals a passage through a valve housing and the passage thereby opens upon pulling the tab out of the valve housing. The control means may further comprise a timer and memory means. The memory means may include information specifying a pre-defined sequence and a pre-defined period of time. In this embodiment, the control means may be configured to effect the pre-defined sequence which may particularly include the following steps: a) Firstly, the inflation medium is heated, e.g. during simultaneous pressure correction by operation of the deflation means to prevent early inflation of the balloon due to thermal expansion of the inflation medium; The first step is typically carried out before the bladder is inserted into the uterus; b) When the inflation medium is heated, the control means may provide a ready signal indicating that the bladder may now be inserted in the uterus and that the ablation can therefore begin; c) Secondly, the inflation means is operated in a positive direction to inflate the bladder; before this second step, the control means may wait for an activation signal to be given by the user. For this purpose, the apparatus may include a button or similar control for starting the process when the bladder is inserted into the uterus. d) Thirdly, the pressure in the bladder is maintained during the pre-defined period of time; e) Fourthly, the inflation means is operated in a negative direction to deflate the bladder; and f) Finally, a finish signal indicating deflation of the bladder is transmitted and the bladder can be removed from the uterus.

The process may include further steps of repeated deflation and inflation of the bladder. This is carried out between the above mentioned step c) and d) such that the bladder is repeatedly emptied and filled with the inflation medium during the pre-defined period of time. For each of these cycles, the bladder may be kept in the inflated state for a period in the range of 10-50 percent of the pre-defined period of time. At any step or between any of the steps, the emergency release structure can be activated to thereby drain the bladder and stop the treatment.

The control means may automatically activate the emergency release structure based on the duration of the treatment. In one embodiment, the control means activate the emergency release structure independently upon the status of the treatment once a pre specified time has elapsed.

In one embodiment, the apparatus comprises a storage chamber containing an amount of the inflation medium, and the inflation means pumps the inflation medium from that storage chamber into the bladder.

Particularly, the storage chamber may contain a larger amount of the inflation medium than what is necessary for inflating the bladder. In this embodiment, the heating means may be configured to heat the entire amount of the inflation medium, and the repeated deflation and inflation of the bladder may cause mixing of that portion of the inflation medium which is in the bladder with that portion of the inflation medium which is in the storage chamber. As a result of the repeated deflation and inflation of the bladder, the bladder may become reheated several times during the treatment, and a more constant high temperature of the surface of the bladder can be obtained.

The storage chamber may be formed by the inflation means itself - i.e. the storage chamber may form a chamber of a pump which is used for inflating the bladder.

The emergency release structure may particularly be configured for releasing the inflation medium from the storage chamber, and it may therefore form a passage from the storage chamber to the disposal storage or simply out of the apparatus.

The inflation means may particularly be driven by power driven means and it may constitute a power driven pump, e.g. a displacement pump, or a centrifugal pump. The pump may e.g. form the structure of a syringe or the structure of a peristaltic pump etc. The apparatus may further comprise motor control means configured to determine a power consumption of the inflation means. The previously mentioned step f) of transmitting a finish signal may be triggered by detection of increased power consumption which will typically occur when the power driven pump reaches an end-stop.

The use of a power driven syringe facilitates in a simple manner, an exact displacement of the inflation medium into the bladder and thus controlled expansion of the bladder.

The power driven means may work on the cylinder or on the piston to move that element relative to the other element of the syringe structure. The syringe structure also effectively forms the aforementioned storage chamber whereby the inflation means itself forms the storage chamber. The emergency release structure may form a passage from the cylinder to the disposal storage or simply out of the apparatus.

Particularly, the combination between power driven means and a syringe structure enables precise dosing of the inflation medium into the bladder by use of very simple and cheap motors. Relative displacement of the cylinder and piston may e.g. be effected by a worm shaft etc. or it may generally be based on a threaded engagement between a driven and a driving element, e.g. between a nut which is rotated by the motor and therefore constitutes the driving element and a threaded piston or threaded element connected to the piston and which thereby constitutes the driven element. The power driven means used for driving the inflation means, i.e. e.g. the above mentioned driving element, could particularly be constituted by a rotary motor of the kind including a rotor and a stator, e.g. a DC motor. Alternatively or additionally, the power driven means may include electromechanical actuation means, e.g. in the form of a solenoid operating e.g. to move a piston and cylinder relative to each other. The apparatus may particularly be independently powered. Herein, independent powering means that the device contains a local source of electrical energy, in the following simply referred to as a battery.

By the term "battery" is herein meant a number of cells, e.g. 1, 2, 3, 4 or more cells, each capable of delivering electrical power. Particularly, the battery may comprise at least one electrochemical cell and/or at least one capacitor.

The battery may typically deliver between 3 and 20 volt and have about 500-2600 mAH of capacity. It may be for disposable, one time usage or it may be rechargeable for multiple usages.

Particularly, it is an object to make a completely independent, single piece device, e.g. for single use. Typically, however, batteries should be disposed in containers specifically for receiving batteries, and typically, instruments which may have been contaminated with biological material, such as blood and tissue, should be disposed in other containers specifically for that purpose. It may therefore be an advantage if the device comprises a detachable independent powering means designed for intended destruction by which the battery, capacitor, or similar power source becomes detached from the chassis such that reassembly becomes difficult or impossible. To make a completely independent device, not only power but also all other necessary elements may be included in a single piece device. Accordingly, the apparatus may be formed by a single entity or component which comprises all the claimed features including the inflation medium and the inflation means such that a separate supply of the inflation medium becomes unnecessary.

The bladder may be pre-shaped e.g. to approximate the bicornual shape of the uterus. It may be manufactured from a bio-compatible, non-allergenic material, and it may come in different sizes, e.g. in two pre-shaped sizes; one for nulliparous uteri and one for parous uteri . The bladder may also have completely different shapes for non-endometrial balloon ablation. The bladder could be made from an elastically deformable rubber, silicone or latex material. In one embodiment, the bladder comprises at least a first and a second balloon positioned one within the other to increase safety if one balloon should be ruptured.

In one particular embodiment, the bladder comprises a first and a second balloon, one within the other, and the inflation medium is injectable between the two balloons, i.e. the space between the first and second balloon forms a reservoir for the heated inflation medium while the inner balloon could be filed with an alternative inflation medium, e.g. in an unheated state.

In this embodiment, the inner balloon may e.g. be expanded by air. Since it is only the space between the first and second balloon which is filled with the heated inflation medium, the amount of heated inflation medium which is necessary for a treatment can be reduced whereby the thermal capacity of the system is reduced. This reduces also the necessary thermal energy for bringing the inflation medium to the requested temperature and the time it takes to heat the inflation medium. As a further advantage, the inflation medium cools down faster and the risk of unintended burns can be reduced. The heating means may e.g. be incorporated in, or it may form part of the inflation means. Particularly, the heating means may form part of the previously described cylinder or piston. In this way, relative movement between the cylinder and piston causes also relative movement between the heating means and one of the cylinder and piston. This may increase the thermal convection and facilitate a more homogeneous temperature of the inflation medium.

The inflation medium may particularly be heated to a temperature above 100°C and more particularly to a temperature above 130°C such as to a temperature in the range of 120- 150°C or in the range of 120-160°C. To reach this temperature, the inflation medium may particularly be a liquid with a boiling point above 150°C and preferably even above 200°C. The inflation medium may particularly be glycerol, e.g. C₃H₈0₃.

Further, the bladder may desirably be made from a material which resists temperatures above 150°C, or above 200°C, and desirable be made from a material which exposes at most 5 per cent change in module of elasticity during a temperature increase from 20°C to 150°C, where the module of elasticity is defined as a tendency of the material to be deformed elastically (i.e., non-permanently) when a force is applied to it.

This relatively high temperature may reduce the duration of the treatment but it may also introduce a risk of damaging the cervix and vaginal tissue lining. To prevent such damages, the entire catheter, or at least an insertable part thereof, or at least the proximal end, may preferably be made such that the thermal spreading from the inner surface of the catheter to the outer surface of the catheter is low.

The "insertable part" is herein defined as that part of the catheter which, during use of the device, is inserted into the body of the treated subject, i.e. e.g. into the vaginal canal or the cervical canal. The "proximal end" is herein defined as less than half of the length of the catheter at that end where the bladder is attached to the catheter, i.e. from the bladder and at most half way down, e.g. 1/3, or 1/4 of the way towards the distal end of the catheter.

In one embodiment, the thermal conductivity of the insertable part or of the distal end is lower than the thermal conductivity of the remaining portion of the catheter.

In one embodiment, the entire catheter, the insertable part, or the proximal end has a lower thermal conductivity than the bladder.

In one embodiment, the entire catheter, the insertable part, or the proximal end has first and second coaxial elements extending about a conduit, the first and second elements have different thermal conductivity. Due to the different thermal conductivity, the propagation of thermal energy through the wall of the catheter may be reduced.

Particularly, one of the elements may have a thermal conductivity less than one tenth of the thermal conductivity of the bladder and/or less than one tenth of the thermal conductivity of the other element of the catheter. One element could e.g. be made from steel, e.g. from titanium or stainless steel and the other element could be made from plastic. Preferably, the outer element could be made from plastic while the inner element is made from steel. In one embodiment, the catheter has a layered structure with 3 layers being an inner layer, an intermediate layer and an outer layer.

The inner layer, e.g. of steel, has a relatively small layer thickness. This layer forms structural rigidity and forms the conduit for the inflation medium. The intermediate layer is for thermal isolation and contains a large amount of gas or air. Typically, this material is a foam material, e.g. polyimide. The intermediate layer is in the range of 3-20 times thicker than the inner layer. The outer layer is for encapsulating the intermediate layer and it has a lower surface friction than the intermediate layer. Typically, the intermediate layer is in the range of 1-10 times thicker than the outer layer. In one particular embodiment, the catheter has an outer diameter being 5.4 mm. i.e. the outer layer forms a tube with a diameter of 5.4 mm. The intermediate layer forms a tube with a diameter of 5.0 mm. The inner layer forms a tube with a diameter of 2.5 mm, and the conduit formed within the inner layer has a diameter of 2.1 mm.

Fibre composite materials typically have a low thermal conductivity. To prevent excessive temperatures on the outer surface of the catheter, the entire catheter, the insertable part, or the proximal end of the catheter could be made from a fibre composite material, e.g. a glass fibre or carbon fibre reinforced polymer material.

The entire catheter, the insertable part, or the proximal end could be covered at least partly with a surface layer of a bio-compatible material, e.g. with a hydrophilic coating, a coating of Poly-tetra-fluoro Ethylene (PTFE), or simply coated with a layer of hydrogel. PTFE may provide an additional advantage since it has a very low thermal conductivity and it may therefore prevent high temperatures on the outer surface of the catheter.

To further prevent damages to the cervix and the vaginal lining, the inflation means may inflate the bladder while the inflation medium is heated. In that way, the vaginal lining is contact with the bladder while the temperature increases, and the duration in which the vaginal lining is in contact with the maximum temperature can be reduced.

To avoid spillage of the inflation medium and to avoid potential scalds caused by the hot inflation medium, the apparatus may comprise a liquid absorbing material arranged to receive the inflation medium which is drained from the bladder. The liquid absorbing material may e.g. include a hydrophilic material, e.g. including polyvinylpyrrolidone (PVP) or other materials well known for their liquid absorbing properties, and it may e.g. be included in the disposal storage. The device may comprise separate sensors for sensing temperature and pressure. The device may also comprise several sensors capable of sensing temperature and/or several sensors capable of sensing pressure, and control logic capable of reading several pressure and/or temperature signals from the sensors and to determine a fault situation in case the difference between the signals from two identical sensors is above a limit value.

In one embodiment, the control means is configured for a fully automatic treatment. For this purpose, the control means may be configured to execute a sequence, e.g. comprising the following steps:

1. The user initiates the treatment by turning on the device. By this activity, the control means initiates heating and the pressure is compensated by movement of the inflation means in the negative direction.

2. The bladder is inserted to the site of operation, e.g. into a body cavity such as the uterus for endometrial thermal ablation or into urethra for prostatic ablation.

3. When the bladder is in correct position, the user indicates that the apparatus is in position by pressing a start button. By this activity, the control means will control the inflation means to cause inflation of the bladder. At the same time, a timer could start.

4. After a predetermined duration, the control means initiates circulation of the inflation means, e.g. by emptying and re-filling the bladder a few times, e.g. 2, 3 or 4 times.

5. After a predetermined duration, the control means controls the inflation means to operate in the negative direction and the bladder is emptied. When the bladder is empty, the user is notified that the treatment is finalized and the bladder can be removed from the uterus.

Since the control means is fully automatic, the entire treatment is carried out essentially without intervention from the user and the risk of faults is reduced.

To ensure only one-time usage of the device and disposal of the device after use, the control means may be configured to only allow one single treatment after which the apparatus stops working.

To prevent damaging the bladder during insertion of the catheter into a body cavity such as uterus, the device may comprise a transition body forming a distal termination of the catheter and located inside the bladder. The transition body is softer than the catheter such that it easily deforms and flattens out when reaching the bottom wall of the body cavity into which the bladder is inserted.

Herein, softer is defined as "obtaining a certain degree of elastic deformation by a lower pressure". To seal the body cavity during the thermal ablation procedure, e.g. to seal uterus, the device may comprise a sealing member forming a protrusion on an outer surface of the catheter. The sealing member may e.g. be made from a soft, i.e. easily elastically deformable, polymer material, e.g. a hydrophilic material, e.g. a material containing acrylamide,

polyvinylpyrolidone or other hydrophilic materials prepared such that they swell. Particularly, the sealing member may extend circumferentially on an outer surface of the catheter.

In one embodiment, the sealing member is slidable axially along the outer surface of the catheter to thereby enable positioning of the sealing member at a distance from the tip of the catheter which corresponds to the depth of uterus and cervix of the person which is treated. In one embodiment, the sealing member is made to expand upon contact with the inflation medium contained in the bladder, or upon contact with body liquids. In that way, leakage of the hot and potentially damaging inflation medium e.g. from uterus to the cervical or vaginal canal, e.g. if the bladder is ruptured, can be prevented. The sealing member may form one or more stripes circumferentially about an outer surface of the catheter, e.g. made by coating the outer surface of the catheter with a hydrophilic materiel.

When the catheter is inserted e.g. through cervix, the hydrophilic coating may swell upon absorption of a fluid swelling medium. Particularly, it may swell upon contact with the inflation medium, e.g. in case of leakage of the inflation medium from the bladder, e.g. if the bladder is ruptured. When the sealing body is swelled, it may provide a seal between the cervical canal and the catheter.

In a second aspect, the invention provides a method of aborting treatment of a patient with an apparatus according to the first aspect of the invention. The method comprises the step of activating the emergency release structure to reduce pressure in the bladder and

subsequently removing the bladder from the patient.

BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 and 2 are perspective views of an assembled device according to the invention; Fig. 3 is a side view, in cross section, of a device according to the invention; Fig. 4 illustrates details of the piston;

Fig. 5 illustrates details of the catheter in a cross sectional view; Fig. 6 illustrates details of the chamber,

Figs. 7 and 8 illustrate further details of the chamber,

Figs. 9-11 illustrate different embodiments of a transition body at the proximal end of the catheter inside the bladder;

Figs. 12-16 illustrate different embodiments of stop and sealing members, and Figs. 17-20 illustrate details of one embodiment of the emergency valve. DETAILED DESCRIPTION OF AN EMBODIMENT

Further scope of applicability of the present invention will become apparent from the following detailed description and specific examples. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.

Figs. 1 and 2 illustrate a device 1 for effecting necrosis of the endometrium. The device comprises an inflation medium contained in a reservoir which is constituted by an expandable bladder 2 which is connected by an elongated catheter 3 to a displacement chamber (not shown) housed within the casing 4. The displacement chamber forms part of the inflation means.

The casing is illustrated in a cross sectional view in Fig. 3. The casing houses the

displacement chamber 5, a control means 6, a battery 7, a disposal storage 8 of a liquid absorbing material, and a user interface 9 (Cf. Fig. 4) including buttons 10 for controlling operation of the device and a display 11 for monitoring the temperature and/or the duration of the treatment.

The displacement chamber is constituted by a syringe structure including a piston 12 movable in a cylinder 13 by an electrical motor 14 - in this case a DC servo motor or step- motor.

The control system may particularly provide a fully automatic system managing the entire treatment, i.e. the heating of the inflation medium, the expansion of the bladder, the duration in which the bladder is expanded and the collapsing of the bladder once the treatment is finished. The control system may be integrated in a printed circuit board (PCB) which includes memory, a computer processing unit, and a program executable in the processing unit and configured to make the control system communicate with the heating means, the motor, and/or with the sensors to carry out the processes of: heating the inflation medium until a predetermined temperature is achieved; - operating the motor to control the pressure in the bladder and to inflate and deflate the bladder; counting a duration by a timer; notifying the user when the treatment is finished.

The control system may have storage means in which all data related to the treatment is stored. The control system may further have communication means adapted to provide documentation including data describing a treatment, e.g. the temperature, the duration, the pressure of the inflation medium and/or other data relevant for evaluating the treatment.

The heating means 15 is attached to, and extends inside the cylinder 13. The piston forms a cavity 16 shaped and dimensioned to receive the heating means 15. When the piston is moved in the cylinder, the heating means becomes received in the cavity and the inflation medium therefore becomes displaced or "stirred" in the chamber in the vicinity of the heating means 15. This increases the thermal convection and provides a more equal temperature in the inflation medium. The device further comprises a sensor 17 capable of sensing pressure and a sensor 18 capable of sensing temperature of the inflation medium in the bladder. The sensors communicate with the control means 6.

Fig. 5 illustrates details of the catheter in a cross sectional view. The catheter comprises first and second coaxial elements 19, 20 extending about a conduit 21. The two elements are made from different materials and have different thermal conductivity to thereby reduce thermal spreading from the conduit to the outer surface 22 of the catheter. Between the coaxial elements 19, 20, the device may comprise a third element 23 having very low thermal conductivity. In one embodiment, the coaxial elements 19, 20 are in direct contact without the third element.

Fig. 6 illustrates in a perspective view, the displacement chamber 24 and the motor 25 which constitutes the power driven means.

Figs. 7 and 8 illustrate further details of the chamber 24. In this view, it is illustrated that the chamber comprises an emergency release structure 26 constituted by a rubber tube. The emergency release structure is in fluid communication with the disposal storage 8 which contains a liquid absorbing material. A valve 27 controls the drainage of inflation medium into the body 8. The emergency release structure is operated via the valve e.g. if the power driven means fails, e.g. when the battery is empty or in case of faults. In this embodiment of the emergency valve 27, the valve forms a passage for the rubber tube, and the passage has two dimensions. When the rubber tube is in one part of the passage, a small dimension squeezes the rubber tube and thereby prevents a fluid flow. When the rubber tube is in another part of the passage, a large dimension allows the rubber tube to open and thereby enables a fluid flow. The rubber tube may be configured to prevent permanent deformation in the squeezed state. Figs. 9-11 illustrate different embodiments of a transition between the elongated catheter 3 and the expandable bladder 2. The transition includes a transition body 28 of a very soft and resilient rubber, latex, silicone or similar soft material. The transition body is attached to the proximal end of the catheter 3 or it is formed by the proximal end of the catheter 3. During insertion of the bladder into a body cavity, e.g. the uterus, the transition body may come into contact with a rear wall of the body cavity whereby the user can feel that the full depth of the body cavity has been reached. Upon contact with the rear wall of the body cavity, the transition body is deformed and thereby protects the wall of the body cavity from damages and it protects the bladder from being ruptured by a sharp tip of the catheter. The transition body may include electronic sensing means configured to determine a distance to the rear wall of the body cavity or configured to determine impact between the transition body and the rear wall of the body cavity.

The transition body forms openings 29, e.g. sideways as illustrated in Fig. 9 or rearwards as illustrated in Fig. 10, or upwards as illustrated in Fig. 11. The openings allow the inflation medium to flow from the catheter into the bladder 2. Other softly rounded, bulbous shapes of the transition body may be used. The bladder 2 is adhesively attached to the outer wall 30 of the catheter 3 such that the transition body becomes included in the space 31 inside the bladder. Figs. 12-15 illustrate different embodiments of stop and sealing members 32 for use of the device for endometrial ablation. The stop and sealing members cooperate with the cervix to provide a sealed passage of the catheter and bladder into the uterus. The embodiment illustrated in Fig. 15 includes two swellable bodies 33 located between an outer surface of the catheter and a sheath 35. When swelling, the swellable bodies presses the sheath against a surface of cervix and thereby seals the passage into uterus. The swellable bodies may e.g. be of a hydrophilic material.

Fig. 16 illustrates two different catheters 36, 37. The catheter 36 has a single hydrophilic surface layer 38 provided as a coating about the body 39. The catheter 37 comprises three hydrophilic surface layers 40, 41, 42. Figs. 17-20 illustrate details of another embodiment of the emergency valve 43 for the emergency exit 26, the exit and valve form an emergency release structure according to the invention.

The emergency valve controls a flow of the inflation medium into the disposal storage 8 or simply out of the apparatus. The emergency valve connects to the rubber hose 26 and comprises first and second valve parts 44, 45. The first valve part 44 receives the inflation medium via the inlet 46 and delivers the inflation medium to the outside or to the disposal storage via the outlet 47. The second valve part 45 comprises a plug element 48 insertable into the opening 49 in the first valve part 44 and thereby blocks the passage between the inlet 46 and the outlet 47. The second valve part is connected to or forms a pull tab 50 which can be reached on the outer surface of the apparatus. The user thereby operates the emergency release structure by pulling the pull tab whereby the first and second valve parts separate and the inflation medium drains out of the apparatus or into the disposal storage. As it appears from the description and drawings, the emergency release structure is completely independent on electrical power, i.e. completely non-electrically operated and activation of the emergency release structure prevents further use of the apparatus.

Claims

1. An apparatus (1) for treating uterine disorders by effecting necrosis of a uterine

endometrium, the apparatus comprising :

• a catheter (3) having a proximal end and a distal end; · a bladder (2) attached to the proximal end for insertion into uterus and being

distendable upon introduction of an inflation medium;

• inflation means (12, 13, 14) connected to said distal end for introducing the inflation medium into the bladder;

• heating means (15) for heating the inflation medium to a temperature sufficient to effect tissue necrosis; and

• control means (6) communicating with the inflation means for controlling the inflation of the bladder, wherein the apparatus comprises an emergency release structure (8, 26, 27, 43) which can be activated independent on the control means to reduce pressure in the bladder.

2. An apparatus according to claim 1, where the emergency release structure (8, 26, 27, 43) forms a manually operable emergency valve (27, 43) arranged to control a flow of the inflation medium

3. An apparatus according to claim 1 and 2, comprising a disposal storage (8) for receiving the inflation medium upon activation of the emergency release structure.

4. An apparatus according to any of the preceding claims, where the inflation means and the control means are electrically operated and the emergency release structure is non- electrically operated.

5. An apparatus according to any of the preceding claims, where the emergency release structure comprises an activation means arranged externally for access outside the apparatus.

6. An apparatus according to claim 5, wherein the activation means is connected to a valve housing and opens a passage upon removal from the valve housing.

7. An apparatus according to any of the preceding claims, where the catheter, the bladder, the inflation means, the heating means, and the control means are joined inseparably to form integral parts of a mobile unit.

8. An apparatus according to claim 7, where the mobile unit, in one end forms a handle suitable for manipulation of the unit by hand, and where the catheter and bladder forms an opposite end of the mobile unit.

9. An apparatus according to claim 3 and any of claims 7-8, where the disposal storage forms integral part of the mobile unit.

10. An apparatus according to any of the preceding claims, where the control means is configured to determine activation of the emergency release structure.

11. An apparatus according to claim 10, where the activation of the emergency release structure is determined by the control means by detection of a pressure drop.

12. An apparatus according to any of the preceding claims, where activation of the emergency release structure prevents subsequent increase of pressure in the bladder.

13. An apparatus according to any of the preceding claims, where the emergency release structure can't be de-activated once it is activated.

14. A method of aborting treatment with an apparatus according to any of claims 1-13, the method comprising the step of activating the emergency release structure to reduce pressure in the bladder.