BALLOON CATHETER

Abstract

The invention relates to a balloon catheter, in particular for expanding stents in fenestrations and for T-branch prostheses, with a balloon (4), a supply line in the catheter (2) to the balloon (4), which allows pressure to be applied to the balloon (4), and a central lumen (3) for a guide wire. In the expanded state, the balloon (4) has at least two regions (P, D, M) with different diameters, these regions merging into one another while forming a step.

Description

balloon catheter The invention relates to a balloon catheter, in particular for the expansion of stents in fenestrations, for T-branch prostheses and for shunts, with a stepped balloon, a supply line in the catheter to the balloon which allows the balloon to be pressurized, and a central lumen for a guide wire. Balloon catheters have been used for many years to dilate stents in blood vessels. To dilate a stent, it is crimped onto the balloon catheter, which then dilates and positions the stent at the desired implantation site. The balloon catheter is then removed from the vessel without the stent. Stents are also used with the help of balloon catheters in connections between two blood vessels (so-called shunts), for example in the liver when creating a TIPS (Transjugular Intrahepatic Portosystemic Shunt) in case of narrowing of the portal vein or high blood pressure in the liver. In angioplasty, balloon catheters are used to mechanically widen a narrowed vessel and to press plaques formed there against the vessel wall. A particular problem arises when, in the area of ​​vascular bifurcations, both the main branch and the branch itself need to be stented. In this case, a fenestrated stent is first inserted into the main branch and implanted so that the fenestration is located at the bifurcation. Then, another stent is placed into the bifurcation, dilated, and expanded to match the stent in the main branch. This usually requires several separate steps, especially if the branching vessel narrows along its course, necessitating a staged expansion. Furthermore, the stent in the branch must be adapted to the fenestration and the course of the stent in the main branch. This adjustment can be achieved by using several balloons of different diameters, inserted sequentially. Alternatively, a so-called "balloon-within-a-balloon" technique is employed, in which two balloons are coupled together so that they can be pressurized separately and used for different expansions. The disadvantage of using multiple separate balloons is the increased effort involved. The object of the invention is to provide a balloon catheter with which stents can be precisely placed in branching vessels or shunts and, if necessary, also connected to a stent placed in the main branch with a fenestration, taking into account a narrowing diameter of the branching vessel. This task is solved with a balloon catheter of the type described above, in which the balloon in the expanded state has at least two areas with different diameters, these areas transitioning into each other with a step. The balloon catheter according to the invention comprises a catheter shaft, a stepped balloon, a lumen for pressurizing the balloon, and a lumen for a guidewire. The balloon itself is stepped, such that at least one region has a larger diameter than another region. Stepping in this context means that the individual segments, for example, the proximal and distal regions, transition into one another with a step, the step occurring within a relatively narrow range. The balloons of the balloon catheters according to the invention have two or more regions with different diameters. For example, the proximal region can have a larger diameter than the distal region, which is advantageous for the placement of stents in side branches of a main vessel.However, the distal portion of the balloon can also be wider than the proximal portion, which, for example, facilitates the placement of a stent in a side branch if access is gained through that side branch. In this case, the expanded part of the balloon is placed in the main vessel at the origin of the side vessel, allowing the stent to expand at the inlet of the side vessel. Furthermore, balloon catheters according to the invention can also have several stages along their entire length, which is advantageous, for example, in constricting vessels, or a central area with a reduced diameter compared to the proximal and distal areas. The latter variant is suitable, for example, for placing stents in shunts, such as in the Tl PS procedure, where it is important to fit the stent precisely into the shunt and at the same time not to expand too much in order to achieve flow regulation. The balloon catheter according to the invention can be used both for the dilation of vessels without placing stents and for the placement of stents. For this purpose, the stents are crimped onto the balloon, and they can extend over the entire length of the balloon or only over a portion of it. For example, when placing a stent in a vessel branch, the stent is crimped onto the balloon so that it extends into the area of ​​the step and, when the balloon expands, widens at this end into a trumpet shape, thus adapting to the wall of the main vessel or to a stent placed within a main vessel. The balloon sections of the balloon catheter according to the invention represent individual segments corresponding to the steps. These segments can be interconnected or separated from each other by walls. The balloon, for example, has an expanded proximal section and a reduced distal section. The distal section is relatively slender. It can have a uniform diameter along its length, but can also taper further towards the distal end of the catheter to allow for adaptation to narrowing side branches. The proximal region of the balloon in the balloon catheter according to the invention has a significantly larger diameter compared to the proximal region. In particular, the diameter is increased by approximately 50 to 100%. Between the proximal and distal sections of the balloon, there may be a middle section with a diameter intermediate between that of the proximal and distal sections. In this case, the balloon has a three-stage design. A four-stage design is also possible, with the diameters of the individual segments decreasing from proximal to distal. In this variant, the balloon typically has a diameter (in expanded state) of 5 to 14 mm in the proximal area and 2 to 6 mm in the distal area. If the balloon has a proximally expanded area, its flanks exhibit a relatively steep slope, preferably uniform on both sides—that is, the slope from the catheter shaft on one side and the slope from the proximal part of the balloon on the other. Advantageously, the slope is 45 to 75° with respect to the catheter axis. A steep slope of the expanded zone is beneficial for the trumpet-shaped expansion of the stent at the branch inlet and for its adaptation to the stent placed in the main branch or to the main vessel from which the branch originates. The same applies if the distal region of the balloon is wider in diameter than the proximal region, and also if both the distal and proximal regions are wider than the central region. The balloon of the balloon catheter according to the invention can thus be divided into several segments, each segment having a separate supply line for pressurization. The individual segments can each be a single balloon directly adjacent to other single balloons. In this case, the single balloons are expediently connected to one another. The individual segments expediently correspond to the aforementioned proximal, distal, and, if applicable, middle regions, i.e., the individual steps. If single balloons are used, they are glued or welded together at the points of contact, i.e., where the steps are located, preferably spot-welded. The connection of the individual balloons is important for uniform expansion. When using the balloon catheter according to the invention, which is divided into several segments or individual balloons and has an expanded proximal region, the distal region is dilated first for stent placement, followed by the middle region, if present, and finally the proximal region, which requires the greatest dilation and where the stent must be adapted to the fenestration of the stent in the main branch or to the shape of the bifurcation in the branching region. If it is a simple balloon without division into individually dilatable segments, the dilation occurs uniformly over the entire length. In principle, it is possible to surround the balloon catheter with an outer balloon that fits snugly against the underlying inner balloon or balloons. In one variant, the outer balloon serves a safety function; that is, it is not dilated separately but expands along with the expansion of the underlying balloon or its segments or balloons. Alternatively, it is possible to also dilate the outer balloon to achieve pre-expansion and then achieve final expansion via the inner balloon. In any case, the contours of the outer balloon and the inner balloon or balloon segments or balloons are matched to each other. The balloon catheter according to the invention is manufactured in the usual manner, and the materials used are also standard materials for this field. The difference from the prior art lies solely in the design of the balloons. Conventional materials can be used for the balloons. Preferably, a non-compliant material, such as polyamide 12, PET, or nylon, is used for the inner balloon, and a compliant or semi-compliant material, such as silicone rubber, Pebax, PA 1 1, or a mixture of Pebax and PA 1 1, is used for the outer balloon. The invention is explained in more detail by the accompanying drawings. They show: Fig. 1: An overall view of a balloon catheter according to the invention; Fig. 2: a sectional drawing through the balloon catheter of Figure 1; Fig. 3: a sectional drawing of a second variant of a balloon catheter according to the invention; and Fig. 4: a sectional drawing of a double balloon for TIPS procedures. Figure 1 shows a balloon catheter 1 according to the invention with the significantly enlarged proximal region P with steep flanks 7 towards the catheter and 6 towards the distal region D, and the relatively slender distal region D, which tapers distally to the catheter diameter. The catheter 2 passes through the balloon construct 4 and terminates distal to the balloon construct 4. For use, a stent is crimped onto the balloon catheter, which is expanded by the expansion of the balloons and placed in a blood vessel. The illustration shows catheter 1 with an expanded balloon. Figure 2 shows a cross-sectional drawing through the balloon catheter 1 according to Figure 1, with catheter 2, a free lumen 3 for a guidewire for placing the catheter, and the balloon 4. Balloon 4 is differentiated into the proximal region P, the distal region D, the middle region M and the terminal region T. The proximal region P is significantly wider than the distal region D. The middle region M is smaller in diameter than the proximal region P, but has a larger diameter than the distal region D. The transitions from the proximal region P to the middle region M and from the middle region M to the distal region D, as well as in the terminal region T, are formed by relatively steep flanks 6, 8, and 9. Flank 6 is crucial for the adaptation of a stent to the fenestration of a stent in the main branch, or for the adaptation to the vessel wall in the main branch during stent placement. In the terminal region T, the balloon tapers and seals tightly before the end of the catheter 2. The channels used to inflate the balloons with fluid are conventional and are not shown in the diagram. Figure 3 shows a variant of the double balloon according to the invention, in which the balloon 4 is surrounded by an outer balloon 5. The outer balloon 5 provides greater safety and, if separate expansion via a further lumen is present, allows for more precise and targeted expansion and adaptation of a stent to the course of the vessel. Otherwise, the balloon 1 in Figure 3 corresponds to the representation in Figure 2. Figure 4 shows a balloon catheter 1 for TIPS procedures, comprising a proximal balloon 1 with an expanded diameter and a distal balloon 10 with a smaller diameter. Both balloons are separately expandable, as required for TIPS procedures in the liver. The two balloons are connected to each other via adhesive or weld points 12, so that they form a single unit when expanded. The lumens for the separate inflation of the balloons are not shown. The lumen 3 for a guide wire for positioning the device 1 is shown. It goes without saying that there are numerous variations in the design of the proximal and distal sections. In one variant, the proximal section is more spherical. The distal section is depicted with the same diameter, but it is easily possible to incorporate a further reduction or tapering towards the terminal end of the catheter. For example, the distal section can have a 40% reduction in diameter along its length towards the terminal end, with this tapering occurring continuously or in steps.

Claims

Patent claims 1. Staged balloon catheter, especially for the expansion of stents in fenestrations and for T-branch prostheses, with a balloon (4), a lead-in line in the catheter to the balloon (4) which allows the balloon (4) to be pressurized, and a central lumen (3) for a guide wire, characterized in that the balloon (4) in the expanded state has at least two regions (P, D, M) with different diameters, wherein these regions (P, D, M) transition into each other by a step.

2. Balloon catheter according to claim 1, characterized in that the balloon (4) has multiple stages, in particular triple stages.

3. Balloon catheter according to claim 1 or 2, characterized in that the proximal region (P) of the balloon (4) is opposite the distal region (D) is expanded by 50% to 100%.

4. Balloon catheter according to one of the preceding claims with a three-stage design, characterized in that the diameter in the middle region (M) is smaller than in the proximal region (P), but larger than in the distal region D, in each case referring to the expanded state.

5. Balloon catheter according to claim 1 or 2, characterized in that the distal region (D) of the balloon (4) is extended by 50% to 100% compared to the proximal region (P).

6. Balloon catheter according to claim 1 or 2, characterized in that the proximal (P) and distal (D) regions of the balloon (4) are extended compared to the middle region (M).

7. Balloon catheter according to one of claims 1 to 6, characterized in that the expanded area has a steep rise of the flanks. (6, 7) shows.

8. Balloon catheter according to claim 5, characterized in that the slope of the flank is 45 to 75°, relative to the catheter axis.

9. Balloon catheter according to one of the preceding claims, characterized in that the balloon (4) is divided into several segments, each segment having a separate supply line for pressurization.

10. Balloon catheter according to claim 9, characterized in that the individual segments are each individual balloons that are directly adjacent to neighboring individual balloons.

11. Balloon catheter according to claim 10, characterized in that the individual balloons of the individual segments are connected to each other at their end faces.

12. Balloon catheter according to any one of claims 9 to 11, characterized in that the segments correspond to the steps of the balloon (4).

13. Balloon catheter according to any one of the preceding claims, characterized in that the balloon (4) is surrounded by an outer balloon (5).

14. Balloon catheter according to one of the preceding claims with crimped stent.