Cryoablation device

Abstract

The cryoablation device of the present invention uses a first distal balloon and a second proximal balloon mounted on a shaft. The proximal balloon is used to position a distal balloon, also referred to as a cryogenic balloon, to which a cooling medium is supplied to perform cryoablation. The shaft serves to bring the balloon to a predetermined location within a patient and provides a plurality of lumens, e.g., for supplying media to the proximal and distal balloons, respectively.

Description

Technical Field

[0001] The present invention relates to a cryoablation device, which comprises a cryoballoon for performing cryoablation, and is particularly suitable for performing cryoablation on the stomach using a cooling medium supplied to the cryoballoon. Background Art

[0002] Obesity is a contributing factor to many serious diseases such as diabetes, joint damage or heart failure. In addition to non-invasive treatments such as diet or physical activity, there are also effective invasive surgeries and interventions such as sleeve gastrectomy, gastric banding, intragastric balloon, gastric bypass, gastric pacemaker, botulinum toxin injections or vagus nerve gastric branch ablation.

[0003] During pulmonary vein ablation for atrial fibrillation, the principle of circumferential cryoablation was used. Summary of the invention

[0004] The present invention relates to a cryoablation system for cryoablation, in particular to a cryoablation of the gastric branch of the vagus nerve on the stomach wall extending from the anterior and posterior gastric fundus to the pylorus.

[0005] Various aspects, examples and exemplary steps of the present invention and their implementation are disclosed below. According to the present invention, different exemplary features can be combined in a technically feasible and implementable manner.

[0006] Detailed description of the invention

[0007] The following briefly describes the specific features of the present invention, but it should not be understood that the present invention is limited to only the features or feature combinations described in this section.

[0008] The cryoablation device of the present invention uses a proximal balloon and a distal balloon mounted on a shaft. The proximal balloon is used to position the distal balloon, and the distal balloon is supplied with a cooling medium to perform cryoablation. The shaft is used to bring the balloon to a predetermined position in the patient's body and provides a plurality of cavities, for example, for supplying a medium to the proximal balloon and the distal balloon, respectively.

[0009] General Description of the Invention

[0010] This section describes general features of the invention by reference to possible implementations of the invention.

[0011] The present invention relates to a cryoablation device, comprising a shaft having a proximal end and a distal end, a first airbag arranged at the distal end of the shaft, and a second airbag arranged on the shaft and located at the proximal side of the first airbag. The first airbag is a cryobag, also known as a distal airbag or a cryobag. The second airbag is a positioning airbag, also known as a proximal airbag or a positioning and protection airbag. The shaft can be, for example, a multi-lumen catheter.

[0012] In this case, the expression "at the distal end of the axis" may mean that the axis does not extend beyond the distal end of the first airbag at all, or only extends beyond the maximum length of the distal end of the first airbag, which maximum length may be an absolute length, such as 5 cm, 2 cm, 1 cm, 0.5 cm, 0.2 cm or 0.1 cm, or a fraction of the axis length, such as 5%, 2%, 1%, 0.5%, 0.2% or 0.1% of the axis length.

[0013] The distal end of the shaft may be located within the first balloon. In this case, the first balloon can rotate around the distal end of the shaft. In another embodiment, the first balloon is completely located on the shaft, which means that both the proximal and distal ends of the first balloon are connected to the shaft.

[0014] When in use, the distal end of the shaft is inserted into the patient's body to bring the first balloon and the second balloon in a deflated state to the target position for ablation. For example, the distal end of the shaft is inserted orally and guided to the stomach through the esophagus. The shaft is preferably flexible.

[0015] The shaft includes at least one first outlet located in the first airbag and at least one first supply lumen terminating at the at least one first outlet. A cryogenic medium (such as N2O or CO2) is supplied to the first airbag through the first supply lumen and the first outlet. The cryogenic medium expands the first airbag so that it abuts or rests against the tissue to be treated. The cryogenic medium then absorbs heat from the tissue in contact with the first airbag.

[0016] The first outlet may serve as a throttling device to expand the refrigerant medium when it enters the first air bag from the first supply chamber.

[0017] The first outlet may be referred to as a frozen outlet, and the first supply cavity may be referred to as a frozen supply cavity.

[0018] The other end of the first supply lumen, ie the end not terminating in the at least one first outlet, is connected to a source of cryogenic medium, such as a cryogenic medium storage tank or a cassette. The connection may be direct or indirect, ie via an additional conduit located at the proximal end of the shaft.

[0019] The shaft also includes at least one second outlet located in the second balloon and at least one second supply lumen terminating at the at least one second outlet. A filling medium is supplied to the second balloon through the second outlet and the second supply lumen. The filling medium may be, for example, a liquid, such as water or saline, or a gas, such as air. The filling medium inflates the second balloon.

[0020] The other end of the second supply cavity, i.e. the end not ending in the at least one second outlet, is connected to a filling medium source, such as a syringe or a pump connected to a filling medium reservoir. This connection can be direct or indirect, i.e. via an additional conduit located at the proximal end of the shaft. For example, the second balloon can be supplied and drained with medium via the same second cavity, which means that the second supply cavity can deliver filling medium in two opposite directions.

[0021] The second balloon has several functions. The first function is to position the cryoablation device (and therefore the first balloon) at the target location. In the case of gastric ablation, the second balloon prevents the shaft (and therefore the first balloon) from being pulled into the esophagus. The second function is to straighten the stomach wall when tension is applied to the shaft. The tension straightens the stomach in the craniocaudal or longitudinal direction, causing the first balloon to lie against the stomach wall along a closed curve.

[0022] This enables complete annular ablation.

[0023] The first airbag and the second airbag may each have a housing that is tightly connected to the entire periphery of the shaft. Tight connection means that the freezing medium cannot escape from between the shaft and the first airbag, and the filling medium cannot escape from between the shaft and the second airbag. Therefore, the combination of the shaft and the first airbag or the second airbag forms a volume for accommodating the freezing medium or the filling medium.

[0024] In one embodiment, the second airbag and the first airbag are made of a single shell, which is tightly connected to the shaft at least in two locations: at the proximal side of the second airbag and at the boundary between the second airbag and the first airbag. It can also be selectively tightly connected to the shaft at the distal side of the first airbag. However, the second airbag and the first airbag can also be made of completely independent shells.

[0025] In one embodiment, the outer shapes of the first and second balloons are rotationally symmetric with respect to the axis. This means that the cross-section of each balloon in a plane perpendicular to the axis is circular. In this embodiment, the cryoablation device is essentially rotationally invariant, at least at the target location. Therefore, when using the device, the rotational orientation of the axis and thus the balloons at the target location is irrelevant. However, the shape of the first and / or second balloon can be adjusted according to the shape of the tissue to be treated.

[0026] For example, the shape may be a disk or a ring with parallel or sloping shoulders.

[0027] It should be noted that the shaft is generally flexible so that its distal end can be navigated to a target location. The shaft has an axis, which is defined as the center of the shaft along the proximal-distal direction of the shaft. Thus, a plane perpendicular to the shaft means that the plane is perpendicular to a tangent to the axis at the location where the plane intersects the shaft.

[0028] In one embodiment, the diameter of the second airbag is 2.5 to 5 cm, and the diameter of the first airbag is 1.25 to 2 times the diameter of the second airbag. In this document, unless otherwise specified, all dimensions and / or ratios are given for the inflated state of the airbag at its nominal pressure. The nominal pressure is greater than the pressure at the target location, for example at most one atmosphere, in particular 0.5 atmosphere.

[0029] In the cryoablation device for gastric ablation, the diameter of the first balloon is, for example, greater than 5 cm, for example, between 6 and 10 cm. The diameter of the second balloon is, for example, between 3 and 4 cm.

[0030] In one embodiment, the first airbag and the second airbag are short airbags. Here, "short" means that the maximum diameter of the airbag is greater than the length of the airbag, for example, twice, three times or four times. The length of the airbag refers to the distance between the two ends (proximal end and distal end) of the airbag and the axis in the axial direction. It can also be measured as the maximum extension of the airbag in the axial direction. The length of the second airbag and / or the first airbag is, for example, 25 mm or less.

[0031] The short nature of the balloon, especially the short nature of the first balloon, results in a smaller contact area between the balloon and the tissue to be treated. Therefore, in one implementation, the first balloon is short, but the second balloon is not necessarily short.

[0032] The second airbag and / or the first airbag are made of, for example, a semi-compliant material. Once the airbag made of a semi-compliant material, i.e., a semi-compliant airbag, reaches its nominal size, it will only increase in size slightly with increasing internal pressure.

[0033] In one embodiment, the distance between the first airbag and the second airbag along the axis is 5 cm or less, such as 2 cm, 1 cm, 0.5 cm or less. The distance here refers to the distance between the distal end of the second airbag and the proximal end of the first airbag. The end of the airbag is the point where it is tightly connected to the axis.

[0034] The distance between the first balloon and the second balloon is typically selected based on the intended application of the cryoablation device. In the case of gastric wall ablation, if tension is applied to the shaft to hold the second balloon against the esophagus, the height of the tissue to be ablated in the cranial and caudal direction is determined by the distance between the second balloon and the first balloon. The first balloon is then held at a determined distance from the cardia.

[0035] In one embodiment, the shaft further comprises a first exhaust lumen in communication with the interior of the first balloon. The first exhaust lumen allows the cryogenic medium to be exhausted from the first balloon, for example for deflation of the first balloon or for achieving a continuous flow of cryogenic medium, thereby exhausting the cryogenic medium heated during the ablation process and supplying fresh cryogenic medium. The first exhaust lumen may be connected to a pump or any other device for exhausting the cryogenic medium from the first balloon. The connection may be made at the proximal end of the shaft, either directly or indirectly via an additional catheter located at the proximal end of the shaft.

[0036] In one embodiment, the shaft comprises a plurality of first outlets distributed around the circumference or distal end of the shaft. For example, a plurality of cryogenic outlets are evenly distributed around the circumference of the shaft. For example, if the shaft terminates in the first airbag, the plurality of outlets are located at the distal end of the shaft.

[0037] Through the plurality of first outlets, the temperature of the periphery of the first airbag in contact with the tissue can be made as uniform as possible. The shaft includes, for example, 4, 6, 8, 10, 12 or 16 first outlets.

[0038] In one embodiment, the number of the first supply chambers is equal to the number of the first outlets. In this embodiment, each first supply chamber is associated with a first outlet and terminates at the outlet. By adjusting the supply of the cryogenic medium to the plurality of first supply chambers, the temperature distribution of the first airbag circumference in contact with the tissue can be controlled. The more cryogenic medium is applied to a specific first outlet, the lower the temperature of the first airbag periphery at a position facing the specific first outlet.

[0039] However, a first supply cavity less than the number of first outlets may be provided. In this case, one first supply cavity may terminate at two or more first outlets.

[0040] In one embodiment, the first supply cavities are evenly distributed along the inner circumference of the shaft. However, two or more first supply cavities may also be combined together, wherein the group of first supply cavities is evenly distributed along the inner circumference of the shaft.

[0041] In one embodiment, the shaft further comprises a ventilation cavity having an external outlet at the distal end of the shaft. The ventilation cavity connects the distal end of the shaft to the outside of the patient's body, for example. In this embodiment, the distal end of the shaft can be any position on the shaft, or on the distal end face of the shaft, which is more distal than the distal end of the first balloon. In the case of gastric wall ablation, the ventilation cavity connects the stomach to the outside of the patient's body to allow digestive gases to escape from the stomach or external air to enter the stomach. If the first balloon ruptures, the freezing medium can escape from the stomach through the ventilation cavity, which avoids excessive expansion or discomfort of the stomach. The same is true for the filling medium if the second balloon ruptures.

[0042] In one embodiment, the ventilation cavity and the second supply cavity are arranged radially opposite to each other in the shaft, which results in a cross section of the shaft being substantially mirror-symmetrical.

[0043] In one embodiment, the ventilation cavity and the second supply cavity are arranged in the wall of the shaft. This means that the wall of the shaft forms both the ventilation cavity and the second supply cavity.

[0044] In one embodiment, at least one (preferably each) of the at least one first supply cavity, the at least one second supply cavity and the ventilation cavity has a circular cross-section in a plane perpendicular to the axis.

[0045] In one embodiment, the portion of the interior of the shaft not occupied by the at least one first supply lumen, the at least one second supply lumen and the ventilation lumen (if applicable) forms a first exhaust volume.

[0046] The shaft has, for example, a circular cross section. In one embodiment, the shaft has an outer diameter of less than 8 mm, such as 5 to 7 mm, in particular 6 mm.

[0047] In one embodiment, the second airbag and / or the first airbag has two shoulders that are tightly connected to the shaft at the radial inner end of each shoulder, and a connecting section connecting the radial outer ends of the two shoulders. The shoulders and the connecting section can be formed in one piece or by two or more parts connected together. In one example, the airbag is continuous at the transition from the shoulder to the connecting section. This means that at the intersection of the plane containing the axis and the airbag, the tangents of the shoulder and the connecting section at the transition point are the same.

[0048] In one embodiment, the shoulder (eg, the shoulder of the first airbag) is in a truncated cone shape, with an opening angle between 70 and 85 degrees, such as between 72 and 78 degrees, in particular 75 degrees.

[0049] This means that the angle between the shoulders in the intersection of the side wall with a plane parallel to the axis is 140 to 170 degrees, for example 144 to 156 degrees, in particular 150 degrees.

[0050] For example, the tapered shoulder is centered about the axis at the connection with the shaft.

[0051] In one embodiment, the connecting section is an arc-shaped connection between the radially outer ends of the shoulders. The arc-shaped connection has a constant radius, for example 4 to 7 mm, in particular 5 mm.

[0052] The shaft may have a joint at or near its proximal end. Near the proximal end, for example, means that it begins at a distance of less than 15 cm, 10 cm or 5 cm from the proximal end. The only limitation is that when the first airbag is at its target position, the joint is located outside the patient's body. The joint has at least one connector, wherein the connector is connected to one of the first supply chamber, the second supply chamber, the first exhaust chamber or the ventilation chamber. The connector can be standardized, such as a Luer connector.

[0053] In one embodiment, the cryoablation device includes a cryomedia supply conveyor (such as a tank or a cartridge) connected to the first supply cavity for supplying cryomedia to the first balloon through the first supply cavity. The cryomedia supply conveyor is, for example, connected to a corresponding connector of the shaft joint.

[0054] In one embodiment, the cryoablation device includes a cryomedia discharge conveyor (such as a pump) connected to the first exhaust cavity for discharging the cryomedia from the first airbag through the first exhaust cavity. The cryomedia discharge conveyor is, for example, connected to a corresponding connector of the shaft joint. In addition to using the cryomedia discharge conveyor, the cryomedia can also be discharged from the first airbag only by the pressure in the first airbag. The cryomedia discharge conveyor can facilitate the deflating of the first airbag when it is removed from the target location.

[0055] In one embodiment, the cryoablation device includes a filling medium conveyor (such as a syringe) connected to the second supply cavity, for supplying the filling medium to the second balloon through the second supply cavity and / or discharging the filling medium therefrom. The filling medium discharge conveyor is, for example, connected to a corresponding connector of the shaft joint.

[0056] In one embodiment, the cryoablation device includes at least one marker. The marker can be used to locate the distal end of the shaft and / or at least one of the second balloon and the first balloon in a medical image of the patient. The marker can be a radiopaque marker visible in an X-ray image, or a marker visible in an ultrasound image.

[0057] In one implementation, the marker may be located distal to the shaft. This means that it is located more distally than the first airbag. In another implementation, the marker may be attached to the airbag. The marker may, for example, have an annular shape centered on the shaft and may be part of or located on the airbag housing.

[0058] In another implementation, when the first balloon is at its target position, the marker is located on the shaft portion that remains outside the patient's body. By means of such a marker, the insertion depth of the shaft can be monitored, for example before inflating the first balloon.

[0059] For example, the present invention does not involve or specifically include invasive procedures involving substantial physical intervention of the body that require professional medical expertise to perform and that would present substantial health risks even with the required professional care and expertise.

[0060] For example, the present invention does not include the step of inserting the distal end of the shaft and the balloon into the patient. For this reason alone, the implementation of the present invention does not require or imply any surgical or therapeutic activity, and in particular, does not require any surgical or therapeutic steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In the following, the present invention is described with reference to the accompanying drawings, which provide background information and show specific embodiments of the present invention. However, the scope of the present invention is not limited to the specific features disclosed in the drawings, wherein:

[0062] Figure 1 The overall structure of the cryoablation device is shown;

[0063] Figure 2 Shows Figure 1 a cross-sectional view of the device shown;

[0064] Figure 3 The supply and discharge of filling medium to the second airbag are shown;

[0065] Figure 4 The supply and discharge of the cryogenic medium to the first air bag are shown;

[0066] Figure 5 shows a cross-sectional view of a first airbag; and

[0067] Figure 6 The shape of the first airbag is shown.

[0068] Description of Specific Embodiments

[0069] Figure 1An example structure of a cryoablation device 1 according to the present invention is shown. The device 1 comprises a flexible shaft 2 having a distal end 2a, a second balloon 3 and a first balloon 4. The first balloon 4 is also referred to as a cryoballoon. The second balloon 3 and the first balloon 4 are tightly connected to the shaft 2. This means that the shaft 2 and the second balloon 3 form a second volume for filling a medium, and the shaft 2 and the first balloon 4 form a first volume for a cryomedium.

[0070] The cryoablation device according to this embodiment is designed for cryoablation of the stomach wall. The shaft 2, the second balloon 3 and the first balloon 4 have sizes suitable for this application.

[0071] In the present exemplary embodiment, the outer shapes of the second airbag 3 and the first airbag 4 are rotationally symmetric with respect to the shaft 2. The first airbag 4 is closer to the distal end 2a of the shaft 2 than the second airbag 3.

[0072] Figure 2 The upper part of FIG. 1 shows a cross-sectional view of the cryoablation device 1 , and Figure 2 The lower part shows that the axis 2 is perpendicular to Figure 2 Enlarged cross section in the plane of the upper section.

[0073] like Figure 2 As shown, the length l of the second proximal airbag 3 p Less than the length l of the first refrigerating air bag 4 c In this embodiment, the length l of the second airbag 3 is p The length l of the first airbag 4 is in the range of 4 to 25 mm, for example about 16 mm. c In the range of 5 to 35 mm, for example about 24 mm. In this embodiment, "length" refers to the extension of the volume enclosed by the corresponding airbag in the direction of the axis 2. The extension ends at the place where the respective airbag is tightly connected to the axis 2.

[0074] In this embodiment, the distance f between the distal end 2a of the shaft 2 and the first airbag 4 is less than the length l of the first airbag 4. c , for example, about 1 to 10 mm. The distance d between the second airbag 3 and the first airbag 4 along the axis 2 is less than the length l of the second airbag 3 p The distance d refers to the distance between the distal end of the volume enclosed by the second airbag 3 and the proximal end of the volume enclosed by the first airbag 4. The end of the volume here refers to the position where the corresponding airbag is tightly connected to the shaft 2.

[0075] The cryoablation device 1 further comprises a joint 5 at the proximal end of the shaft 2 .

[0076] like Figure 2 As shown in the lower part, the shaft 2 has a circular shape and includes a plurality of different cavities. A first supply cavity 9 supplies a freezing medium to the first balloon 4. A second supply cavity 11 supplies a filling medium to the second balloon 3. A ventilation cavity 12 connects the distal end 2a of the shaft 2 with the stomach vent 8 of the connector 5. Through the ventilation cavity 12 and the stomach vent 8, air or other gas can flow from the stomach to the outside of the patient or vice versa.

[0077] like Figure 2 As shown in the lower part, the remaining volume inside the shaft 2 forms a first exhaust chamber 10 for exhausting the refrigerant from the first air bag 4 .

[0078] like Figure 2 As shown in the lower part, the second supply cavity 11 and the ventilation cavity 12 are formed in the wall of the shaft 2 .

[0079] In the joint 5, the second supply cavity 11 is connected to the filling medium port 7, through which the filling medium can be supplied from a filling medium reservoir (not shown, such as a syringe) to the second airbag 3 via the second supply cavity 11. On the other hand, the filling medium can be returned from the second airbag 3 via the second supply cavity 11 and the filling medium port 7, for example, to the filling medium reservoir.

[0080] At the proximal end of the shaft 2, a connector 13 is connected to the first supply chamber 9 to allow the cryogenic medium to flow from a cryogenic medium reservoir (not shown) through the first supply chamber 9 into the first airbag 4. The first exhaust chamber 10 is connected to and terminates at the exhaust port 6. The cryogenic medium is exhausted from the first airbag 4 through the first exhaust chamber 10 and the exhaust port 6. This can be achieved by the pressure in the first airbag 4, or by an additional pump (not shown) connected to the exhaust port 6.

[0081] Initially, the second balloon 3 and the first balloon 4 are in a deflated state, for example, for inserting the distal end 2a of the shaft 2 together with the two balloons into the stomach through the esophagus.

[0082] Figure 3is a cross-sectional view of a portion of a cryoablation device 1, wherein the cross section passes through the second supply cavity 11 and the ventilation cavity 12. As shown, the cryoablation device 1 includes a second supply outlet 14 located in the second airbag 3. The second supply cavity 11 terminates at the second supply outlet 14. A filling medium can be supplied to the second airbag 3 through the second supply cavity 11 and the second supply outlet 14 to expand the second airbag 3. In order to shrink the second airbag 3, the filling medium is discharged through the second supply outlet 14 and the second supply cavity 11. The flow direction of the filling medium is indicated by the arrows in the second supply cavity 11, the second supply outlet 14 and the second airbag 3.

[0083] To perform cryoablation on the stomach wall, the distal end 2a and the first balloon 4 and the second balloon 3 are first inserted into the stomach, and the second balloon 3 is first inflated. The shaft 2 is then pulled in the cranial and caudal direction, which brings the second balloon 3 into contact with the stomach wall and slightly stretches the stomach. The effect of stretching the stomach is to bring the first balloon 4 into contact with the stomach wall along its entire circumference after expansion. The force with which the shaft 2 is pulled can, for example, be in the range of 0.5 kg to 2.5 kg, such as 1 kg or 10 Newtons. The first balloon 4 can be inflated before or after the shaft 2 is pulled, but only after the second balloon 3 is inflated.

[0084] and Figure 3 similar, Figure 4 1 is a cross-sectional view of a portion of the cryoablation device 1, but the cross-section is slightly rotated around the axis of the shaft 2 and intersects some of the first supply lumens 9. Figure 4 As shown, the shaft 2 includes a plurality of first outlets 15 in the first airbag 4. Each first outlet 15 is connected to a first supply chamber 9 to allow the cryogenic medium (e.g., N2O or CO2) supplied through the first supply chamber 9 to flow to the first airbag 4 and be throttled through the first outlet 15 located in the first airbag 4, thereby cooling its inner surface (Joule-Thomson effect). As shown by the arrows, the expanded cryogenic medium is distributed in the first airbag 4 and sprayed onto the inner surface of the first airbag 4, thereby freezing the tissue in contact with the first airbag 4 by heat conduction.

[0085] The shaft 2 further comprises a first outlet 16 located within the first airbag 4 and connected to the first exhaust chamber 10. Once the cryogenic medium cools the outer shell of the first airbag 4, it leaves the first airbag 4 through the first outlet 16 and the first exhaust chamber 10. This means that there is a continuous flow of the cryogenic medium to continuously cool the inner surface of the first airbag 4.

[0086] Figure 52 is a cross-sectional view of the shaft 2 and the first balloon 4, wherein the cross section is perpendicular to the axis of the shaft 2. In the embodiment of the cryoablation device 1 shown in this view, the shaft 2 includes four first outlets 14 and four first supply lumens 9. In order to simplify the figure, only one first outlet 14 and one first supply lumen 9 are marked with reference numbers.

[0087] At each first outlet 14, the refrigerant is throttled at a specific opening angle (as shown by the dashed line) toward the inner surface of the first airbag 4. The opening angle is preferably selected so that the refrigerant is throttled toward the entire circumference of the first airbag 4 facing the first outlet 14.

[0088] The first outlets 14 are preferably evenly distributed along the circumference of the shaft 2. They may have a slit shape extending circumferentially along the shaft 2. In this case, the slit shape means that the length of the first outlet 14 in the circumferential direction of the shaft 2 is greater than the width of the first outlet 14 in the axial direction of the shaft 2.

[0089] Figure 6 The exemplary dimensions of the first airbag 4 are shown. The first airbag 4 is rotationally symmetrical with respect to the shaft 2 and has a maximum diameter of 60 mm. Its length is 24 mm. The first airbag 4 is composed of two shoulders 17 and an arc connection 18 connecting the radial outer ends of the shoulders 17. Each shoulder 17 is similar to a truncated cone and is tightly connected to the shaft 2 at its smaller diameter end. The conical shoulder 17 has an opening angle of 75 degrees, that is, the angle between the shoulder and the axis of the shaft 2. This results in an angle of 150 degrees between the relative line segments forming the shoulder 17.

[0090] The arcuate connection 18 has a constant radius of 5 mm, but can have any shape as long as it closes the gap between the shoulders 17. The arcuate connection preferably transitions to the shoulders in a smooth manner. Figure 6 In the embodiment shown, this is achieved by extending 150 degrees of the arc-shaped connection 18. Generally, if the arc extends at an angle twice the opening angle of the tapered shoulder 17, the transition is smooth.

[0091] The second airbag 3 may have the same structure, including a shoulder and an arcuate connection between its radially outer ends, but with a smaller diameter.

Claims

1. A cryoablation device (1), comprising: a shaft (2) having a proximal end and a distal end (2a), a first air bag (4) disposed at the distal end of the shaft (2), and a second airbag (3) disposed on the shaft (2) and located on the proximal side of the first airbag (4), Wherein, the shaft (2) comprises: at least one first outlet (15) located in the first airbag (4), at least one first supply chamber (9) terminating in said at least one first outlet (15), at least one second outlet (14) located in the second airbag (3), and At least one second supply chamber (11) terminates in the at least one second outlet (14).

2. The device (1) according to claim 1, wherein the outer shapes of the first airbag (4) and the second airbag (3) are rotationally symmetric relative to the axis (2).

3. The device (1) according to claim 2, wherein the diameter of the second airbag (3) is 2.5 to 5 centimeters, and the diameter of the first airbag (4) is 1.25 to 2 times the diameter of the second airbag (3).

4. The device (1) according to any one of claims 1 to 3, wherein the first airbag (4) and the second airbag (3) are both short airbags.

5. The device (1) according to any one of claims 1 to 4, wherein the distance between the first airbag (4) and the second airbag (3) along the axis (2) is 5 cm or less, such as 2 cm or less.

6. The device (1) according to any one of claims 1 to 5, wherein the shaft (2) further comprises a first exhaust cavity (10) communicating with the interior of the first airbag (4).

7. The device (1) according to any one of claims 1 to 6, wherein the shaft (2) comprises a plurality of first outlets (15) distributed at the periphery or distal end of the shaft (2).

8. Device (1) according to claim 7, wherein the number of said first supply chambers (9) is equal to the number of said first outlets (15).

9. The device (1) according to claim 8, wherein the first supply chambers (9) are evenly distributed along the inner circumference of the shaft (2).

10. The device (1) according to any one of claims 1 to 9, wherein the shaft (2) further comprises a ventilation cavity (12) having an outlet located outside the distal end (2a) of the shaft (2).

11. The device (1) according to claim 10, wherein the ventilation chamber (12) and the second supply chamber (11) are arranged radially opposite to each other in the shaft (2).

12. Device (1) according to claim 10 or 11, wherein the ventilation cavity (12) and the second supply cavity (11) are arranged in the wall of the shaft (2).

13. The device (1) according to any one of claims 1 to 12, wherein the shoulder (17) of the first airbag (4) is in the shape of a truncated cone with an opening angle between 70 and 85 degrees.

14. The device (1) according to claim 13, wherein the first airbag (4) further comprises an arcuate connection (18) between the radially outer ends of the shoulder (17).

15. The device (1) according to claim 14, wherein the radius of the arc-shaped connection (18) is constant at 4 to 7 mm.

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