Patent Application
20200338319
The present invention relates to a device for delivering energy and/or measuring electrical activity in a tubular part of a body, for example a blood vessel or a tubular organ, such as ureter, intestine, trachea, renal pelvis, esophagus, ENT tract, comprising a catheter and/or a balloon and at least one electrode.
Intravascular catheters, especially for applications in the heart/thorax region, comprising an active or a passive electrode are already known, which can be introduced into primary veins or arteries, such as the femoral vein, and advanced from there to various locations of the heart or to the coronary vessels. These catheters are used to represent or stimulate the electrical activity of the heart or remove regions exhibiting abnormal electrical activity. The latter, which is the ablation therapy, is used as a treatment for cardiac dysrhythmia, for example.
Furthermore, catheters are used today to achieve a reduction in blood pressure by way of neuromodulation of the renal nerves (renal plexus). This treatment is based on the assumption that the sympathetic nerve strand located near the renal artery influences blood pressure. It was found that partial traumatization of this nerve causes a sustained decrease in blood pressure, and that this treatment is promising in particular for treatment refractory patients who do not respond, or no longer respond, to conventional pharmacological approaches.
By way of known devices for delivering energy and/or measuring electrical activity which are based on a catheter, it is very difficult to achieve reliable contact between the electrodes of the catheter and the vascular wall. Moreover, checking the wall contact prior to denervation by way of X-rays or electrical measurements is only possible with low accuracy.
To achieve this object, an inflatable balloon can be used, as is described in the published prior art U.S. Pat. No. 8,548,600 B2, for example, so as to displace the distal end of the catheter of the electrode, which is disposed in a helical shape on the outside of the balloon, in the direction of the vascular inner wall and to be affixed there. The balloons used for this purpose, which are cylindrical when inflated, however, tend to completely close the treated blood vessel, thereby interrupting the blood flow to the organs located behind of the treated site (in the renal artery, for example, to the kidney), which is not desirable. The occlusion of the vessel has the added disadvantage that the intima of the vessel cannot be cooled by the blood flow in the vessel during the procedure. This damages the intima in a more extensive area.
The object is therefore to create a device that effects reliable contact between the electrode and the vascular wall, while also avoiding the above-described disadvantages.
The above object is achieved by a device in which the elasticity (extensibility) of the envelope of the balloon is less in at least one first region or section than in at least one second region or section different from the first region, wherein the distal end of the catheter comprising the at least one electrode is disposed in the at least one first region.
The above object is alternatively achieved by a device comprising an inflatable balloon and at least one electrode, wherein the at least one electrode is disposed on the outside of an envelope of the balloon, wherein the elasticity of the envelope of the balloon is less in at least one first region than in at least one second region different from the first region, wherein the at least one electrode is disposed in the at least one second region.
The difference in the elasticity between the first region and the second region is designed in such a way here that a difference in height of the envelope of the balloon, when expanded, between the two regions in the radial direction, based on the balloon envelope, is at least 0.5 mm, and preferably in the range between 1 mm and 2.5 mm, so that, for example, the blood flow is not interrupted, or is not entirely interrupted, in this location.
This is achieved, for example, by using materials that have differing moduli of elasticity (elastic moduli) in the first region and the second region for the envelope of the balloon, which is to say a first material is used for the first region of the envelope of the balloon, and a second material that is different from the first material and has a lower modulus of elasticity is used for the second region. [The elastic modulus is an imaginary stress that would elastically extend a sample rod to twice the length (which is to say strain ε=1).] The lower the modulus of elasticity of the material, the more pronounced is the change in longitude thereof at the same stress or, during the inflation of a balloon, at the same pressure, as compared to a material having a higher modulus of elasticity.
The materials listed in the table below can be used for the first or second region of the balloon.
For example, use of the material pairing PI and PU results in a difference in the change of longitude at an approximate 25:1 ratio.
The same material used together with a simple wall thickness for a second region and together with double the wall thickness for a first region still results in a difference in the change of longitude at an approximately 2:1 ratio, with other ratios remaining the same.
The balloon of the device according to the invention comprising a first region and a second region of the balloon envelope, in which the regions have differing strain values, forms an irregular shape when inflated. Due to the lesser elasticity, the first region is not extended as much when the balloon is fully inflated and, consequently, recedes in relation to the second region, which is to say the second region protrudes further, whereby the above-mentioned difference in height is created. As a result, the surface of the inflated balloon is not smooth, but has a relief comprising protruding regions (second regions) and recessed regions (first regions), as well as transition regions therebetween, so that clearances arise for the blood flow or the flow of other body fluids, and the vessel is not entirely closed. In this way, the blood flow in the vessel is not interrupted. In addition to the consistent supply of blood to nearby organs, this has the advantage that the tissue at the denervation or ablation sites continues to be cooled by the blood flow. In this way, deeper lesions can be produced.
Moreover, by disposing the distal end of the catheter comprising the at least one electrode in the at least one first region, secure wall contact of the electrode is established and, consequently, a reliable denervation or ablation result can be achieved. This is accomplished in that the inflated balloon presses the distal end of the catheter against the vascular wall, thereby fixing the position thereof. Furthermore, it was found that pressing the catheter against the vascular wall considerably improves the electrical contact between the catheter and the vessel, and higher electrical conductivity is achieved. Moreover, disposing the distal end of the catheter in the first region having the lower elasticity prevents strain/overextension of the catheter. In the alternative embodiment without catheter, in which the electrodes are provided on the outside of the balloon envelope (and, if necessary, at least partially in the balloon envelope), the secure wall contact is achieved by disposing the at least one electrode in the at least one second region.
In a preferred embodiment of the invention, the envelope of the balloon comprises fibers in the at least one first region, which limit the elasticity of the envelope of the balloon in this region. The elasticity of the fibers disposed in this region is less than that of the envelope of the balloon in the second region. The lesser elasticity in the first region is particularly easy to implement by embedding fibers that have accordingly little elasticity in the volume of the balloon envelope or on the surface thereof. The fibers can be embedded in the balloon envelope by way of an incremental build-up. For example, fibers can be woven onto an inner tube, over which an outer tube is then extruded. On the outside, the fibers can be joined to the balloon envelope by way of adhesive bonding or welding, for example. The fibers of the first region preferably comprise a material or multiple materials from the group consisting of PEEK, PPTA, PI, PA and metals, all materials preferably taking on the form of a ribbon, rope, cord or wire. The balloon envelope can comprise a material or multiple materials from the group consisting of NR, SI, PET, PE and PU, for example.
In another embodiment, the wall thickness of the balloon envelope can be varied so as to implement differing extensibilities, wherein the wall thickness in the at least one first region is greater than the wall thickness in the at least one second region, wherein the wall thicknesses can preferably be varied between 0.01 mm and 0.3 mm. It is advantageous when the wall thickness in the first region is greater than the wall thickness in the second region by at least a factor of 3. Accordingly, it is advantageous when the wall thickness in the first region ranges between 0.01 mm and 0.1 mm, and in the second region ranges between 0.03 mm and 0.3 mm.
So as to achieve a simple arrangement of the distal end of the catheter comprising the electrodes on the surface of the balloon, it is advantageous when the first region has a rhombus shape or when the first region extends in the direction of a longitudinal axis of the balloon or in a spiral shape (helically) about the longitudinal axis of the balloon. The rhombus shape is achieved by mutually intersecting regions extending obliquely with respect to the longitudinal axis in such a way that a second region is disposed within the rhombus outline. Due to the rhombus shape of the first regions, a protuberance- or pillow-like surface relief of the balloon is created when inflated, which yields the above-described clearances for maintaining the blood flow.
A secure arrangement of the catheter comprising the electrodes on the balloon is achieved when the distal region of the catheter is fixed in points on the envelope of the balloon. This can be implemented, for example, by way of a weld or adhesive joint.
In an advantageous embodiment, the at least one electrode disposed on the catheter is designed as a conductive ring or a conductive half shell.
In another embodiment, the catheter can be implemented as a guide catheter (if necessary, comprising an additional lumen for a guide wire). When using the balloon variants shown here, it is also possible, alternatively, to use a stent, and in contrast to known systems, the blood flow is consistently preserved when using such a balloon.
In a further exemplary embodiment of the variant comprising the catheter, the balloon is additionally designed to be electrically active. In this case, at least one electrode is disposed in or on the balloon envelope in the at least one second region and, when inflated, is pushed against the vascular wall, whereby good contact with the vascular wall is established.
Further objectives, features, advantages, and application possibilities of the invention will be apparent from the following description of exemplary embodiments based on the figures. All features described and/or illustrated, either alone or in any arbitrary combination, form the subject matter of the present invention, including independently of their combination in the individual claims or their dependency reference.
In the schematic drawings:
The first exemplary embodiment of a device according to the invention shown in
The balloon can be detachably fastened to the respective shaft. In this way, the device according to the invention can be adapted to the diameter of the respective vessel to be treated by replacing the balloon.
Moreover, electrodes 15 are disposed at the distal end 10 of the catheter shaft, which are preferably designed as annular electrodes.
The differing extensibilities in the first regions 20 and in the second regions 22 can, alternatively, also be achieved by using differing materials in these regions. For example, the balloon envelope can be made of PI in the first regions 20, and of PU in the second regions 22.
In the inflated state, the differing extensibilities of the regions 20, 22 create a difference in height h (see
In the second exemplary embodiment illustrated in
In the third exemplary embodiment shown in
By way of the above-described exemplary embodiments of a device according to the invention, it is possible to achieve secure positioning of the electrodes 15 of the catheter on the inside wall of the treated vessel with good wall contact. Additionally, the first regions 20 receding in the inflated state create clearances, so that the blood can continue to flow in the vessel and thereby cool the treated site on the vessel.
In the exemplary embodiments of a device according to the invention shown in
The exemplary embodiment shown in
In the balloon 112, furthermore a tube 137 for feeding the inflation medium is disposed. Moreover, a clamping ring 140 is provided at the proximal end of the balloon 112, which is used to fix and support the balloon 112, and in particular the non-extensible fibers 123 integrated into the envelope of the balloon 112, on the tube 137. The clamping ring 140 is disposed on the outside of the balloon 112. Such a design comprising a tube for feeding the inflation medium and a clamping ring is also conceivable for the exemplary embodiment shown in
In the exemplary embodiment according to
Finally,
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2016 106 478.5 | Apr 2016 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/057207 | 3/27/2017 | WO | 00 |
