CATHETER SYSTEM FOR CRYOABLATION, IN PARTICULAR CRYOABLATION OF THE GASTRIC WALL

Abstract

A catheter system for cryoablation is described that comprises: a catheter, which extends along its longitudinal axis; at least one cryoballoon which surrounds the catheter around its entire circumference and forms a filling lumen; a cooling lumen, which is separate from the filling lumen, within the cryoballoon, wherein the cooling lumen is arranged at the outer region of the cryoballoon away from the longitudinal axis of the catheter; at least one filling conduit which extends within the catheter and terminates in the filling lumen; and at least one cooling conduit which extends within the catheter and terminates in the cooling lumen.

Claims

1. A catheter system for cryoablation, comprising: a catheter, which extends along its longitudinal axis; at least one cryoballoon which surrounds the catheter around its entire circumference and forms a filling lumen; a cooling lumen, which is separate from the filling lumen, within the cryoballoon, wherein the cooling lumen is arranged at an outer region of the cryoballoon away from the longitudinal axis of the catheter; at least one filling conduit which extends within the catheter and terminates in the filling lumen; and at least one cooling conduit which extends within the catheter and terminates in the cooling lumen.

2. The catheter system according to claim 1, wherein the cooling lumen extends over at least 90 percent of an outer circumference of the cryoballoon.

3. The catheter system according to claim 1, wherein the cryoballoon is rotationally symmetrical.

4. The catheter system according to claim 1, wherein the at least one cooling conduit comprises a feed conduit and a return conduit.

5. The catheter system according to claim 1, further comprising a pH sensor at a distal end of the catheter.

6. The catheter system according to claim 1, further comprising two or more cryoballoons which are arranged next to each other on the catheter.

7. The catheter system according to claim 6, further comprising a distal balloon arranged on the catheter between the distal end of the catheter and a most distal one of the cryoballoons.

8. The catheter system according to claim 7, further comprising a proximal balloon which is arranged proximally with respect to a most proximal one of the cryoballoons.

9. The catheter system according to claim 8, wherein the proximal balloon is arranged on a second catheter, the proximal balloon configured to be shifted in the direction of the longitudinal axis of the catheter relative to the catheter.

10. The catheter system according to claim 1, wherein the catheter comprises a depth scale through which an insertion depth of the catheter into a body can be ascertained.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention shall be described in more detail on the basis of specific example embodiments. The corresponding figures, which are not true-to-scale, show:

[0029] FIG. 1 a frontal view of a catheter system;

[0030] FIG. 2 a lateral sectional representation of the catheter system from FIG. 1;

[0031] FIG. 3 a frontal sectional representation of the catheter system from FIG. 1;

[0032] FIG. 4 another catheter system, comprising a multitude of balloons; and

[0033] FIG. 5 a catheter comprising a depth scale.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a schematic frontal view of a catheter system 1 comprising a catheter 2 and a cryoballoon 3. The catheter 2 extends along its longitudinal axis, which in the representation in FIG. 1 extends into the plane of the paper. The view in FIG. 1 shows the tip of the catheter, i.e. the distal end of the catheter 2.

[0035] The cryoballoon 3 surrounds the catheter 2 around its entire circumference. The cryoballoon 3 has an inner circumference which abuts and is connected to the outer face of the catheter 2 over its entire circumference, such that the cryoballoon 3 is spatially fixed relative to the catheter 2 in the direction of the longitudinal axis of the catheter 2.

[0036] FIG. 2 shows a schematic lateral sectional representation through the catheter system 1 from FIG. 1, in which it can be seen that the cryoballoon 3 which surrounds the catheter 2 has, by way of example, an oval or elliptical cross-section. The outer shape of the cryoballoon 3 is rotationally symmetrical about the longitudinal axis of the catheter 2. The majority of the inner volume of the cryoballoon 3 is taken up by a filling lumen 5, although the cryoballoon 3 also contains a cooling lumen 6 which is situated at the outer periphery, in relation to its distance from the catheter 2, within the cryoballoon 3. The cooling lumen 6 is delineated from the filling lumen 5 by means of a boundary.

[0037] A filling conduit 9, which is connected to the filling lumen 5, extends within the catheter 2. A cooling conduit, which comprises a feed conduit 7 and a return conduit 8, also extends within the catheter 2. The feed conduit 7 is connected to the cooling lumen 6 via a connecting piece 7a which extends within the filling lumen 5. The return conduit 8 is likewise connected to the cooling lumen 6 via a connection 7b, not shown in FIG. 2, through the filling lumen 5. A coolant, for example a cooling liquid, is conveyed via the feed conduit 7 to an entry point in the cooling lumen 6 and passes through the cooling lumen 6 up to an exit point at which it is guided back via the connection 7b and the return conduit 8.

[0038] At its distal end, the catheter 2 also comprises a pH sensor 4 which measures the pH value of a substance at the distal end of the catheter 2, converts it into an electrical signal and transmits the electrical signal, through a conduit in the catheter 2 which is not shown in the figures, to a control device arranged outside the catheter 2.

[0039] FIG. 3 schematically shows a frontal sectional representation through the catheter system 1 from the same direction of view as in FIG. 1. As is clear from FIG. 3, the cooling lumen 6 surrounds the entire circumference of the catheter 2 in a ring-like manner. FIG. 3 also shows the connection 7b which connects the exit point of the cooling lumen 6 to the return conduit 8.

[0040] The cryoballoon 3 consists of an elastic material. The boundary between the filling lumen 5 and the cooling lumen 6 within the cryoballoon 3 likewise consists of an elastic material.

[0041] Use of the catheter system 1 for cryoablation of the gastric wall is described in the following.

[0042] The distal end of the catheter 2 is inserted into the stomach through the esophagus, while the cryoballoon 3 is deflated. Once the catheter 2 is situated in the desired position, a filler such as for example a saline solution is conveyed into the filling lumen 5 via the filling conduit 9, until the outer circumference of the cryoballoon 3 abuts the gastric wall. A coolant is then fed via the feed conduit 7 and enters into the cooling lumen 6 at the entry point via the connection 7a, whence the coolant passes through the cooling lumen 6, as symbolized by the arrows in FIG. 3. The coolant thus cools a circumferential strip of the gastric wall. At the exit point of the cooling lumen 6, the coolant is conveyed back via the connection 7b and the return conduit 8. This results in a constant flow of coolant through the cooling lumen 6.

[0043] As can be seen from FIG. 3, the entry point and exit point of the cooling lumen 6 are immediately adjacent, such that the cooling lumen 6 extends over the entire outer circumference of the cryoballoon 3.

[0044] The term outer circumference in this document means the line which extends once around the entire circumference of the catheter 2 and which is formed by the points which lie on the surface of the cryoballoon 3 and are furthest away from the catheter 2 when the cryoballoon 3 is inflated, i.e. when the filling lumen 5 is filled.

[0045] FIG. 4 shows a schematic sectional representation through a modified catheter system 14 which by way of example comprises cryoballoons 3a and 3b arranged on the catheter 2, wherein the cryoballoon 3a is nearer to the distal end of the catheter 2 than the cryoballoon 3b. A distal balloon 10 is arranged between the distal end of the catheter 2 and the most distal cryoballoon 3a. The distal balloon 10 surrounds the catheter 2 around its entire circumference and has a smaller outer diameter than the cryoballoons 3a and 3b. The catheter 2 likewise comprises a pH sensor 4 at its distal end.

[0046] The catheter 2 is concentrically surrounded by a second catheter 11. The second catheter 11 surrounds the catheter 2 in a region which is proximal with respect to the most proximal cryoballoon 3b. A proximal balloon 12 is arranged on the second catheter 11 and surrounds the second catheter 11, and therefore the catheter 2, around its entire circumference. The proximal balloon 12 is thus arranged proximally with respect to the most proximal cryoballoon 3b. It has for example the same outer radius as the distal balloon 10.

[0047] The second catheter 11 can be shifted relative to the catheter 2 in the direction of the longitudinal axis of the catheter 2 and therefore in the direction of the longitudinal axis of the second catheter 11. The proximal balloon 12 can thus be shifted relative to the distal balloon 10 and the cryoballoons 3a and 3b.

[0048] A supply conduit 13 extends within the catheter 2 and is connected to the inner space of the distal balloon 10. A supply conduit 14 extends within the second catheter 11 and is connected to the inner space of the proximal balloon 12. The distal and/or proximal balloon can be filled with a filler and/or coolant via the supply conduits 13 and 14. The two balloons can also respectively be completely or partially evacuated again via the supply conduits.

[0049] When using the modified catheter system for cryoablation of the gastric wall, the distal end of the catheter 2 is inserted into the stomach while repeatedly ascertaining the pH value by means of the pH sensor 4. It is possible to ascertain, from a change in the pH value, when the distal end of the catheter 2 has reached the stomach. The catheter 2 is then inserted further, and from an increase in the pH value, it is ascertained that the distal end of the catheter 2 has reached the duodenum. The distal balloon 10 is then inflated, by feeding a coolant or a combination of a filler and a coolant via the supply conduit 13. The catheter 2 is then retracted until the distal balloon 10 is situated in the pylorus and cools it. All the cryoballoons 3a and 3b are then inflated, gradually or simultaneously, by filling the corresponding filling lumen 5 with a filler. The coolant is then conveyed into the cooling lumens 6 of the cryoballoons 3a and 3b in order to cool the gastric wall. The proximal balloon 12 is inflated, by feeding a coolant or a combination of a coolant and filler via the supply conduit 14. By means of shifting the second catheter 11 relative to the catheter 2, the proximal balloon 12 is guided up to the cardia and cools it.

[0050] Instead of separate supply conduits 13 and 14 for the distal balloon 10 and/or proximal balloon 12, it is also possible to provide a shared supply conduit which is connected to the inner volume of both the distal balloon 10 and the proximal balloon 12.

[0051] FIG. 5 schematically shows a catheter 2 comprising a depth scale arranged on it. When the catheter 2 is inserted, it moves along its longitudinal axis past a reference 16 which is for example spatially fixed relative to the entry point of the catheter 2. The insertion depth of the catheter 2 can be determined from the depth scale 15, from which the position of the distal end of the catheter 2 can for example be derived.