Field

[0001] The present invention relates to a catheter for the opening of obstructions in bodily vessels. The present invention further relates to a method for opening an obstruction in bodily vessel using the catheter.

Background

[0002] Blood vessels, and in particular arteries, are susceptible to occlusion by sclerotic plaques, emboli, and foreign bodies. Once a blood vessel is partially occluded, laminar blood flow is disrupted and lipid deposition and total occlusion can ensue. Over time, a tough fibrous cap may form over the lipids of a total occlusion to form a chronic total occlusion.

[0003] Chronic total occlusions in the coronary arteries prevent the direct supply of oxygenated blood to downstream myocardium thereby reducing cardiac function. In the absence of a sufficient supply of oxygenated blood, cardiomyocytes may become necrotic or go into a hibernating state in which they remain alive by drawing a reduced blood supply from collateral vessels, but do not contract normally. [0004] Revascularization, either by coronary artery bypass graft or by opening up a passage through the chronic total occlusion, can return hibernating cardiomyocytes to their normal contractile state thereby improving cardiac function.

[0005] In order to open the tough fibrous cap of a chronic total occlusion, a cutting device is typically employed to cut a small passage through the chronic total occlusion before a series of dilation balloons of increasing diameter are inserted into the passage to progressively widen it. This process is long and laborious as, for each time that a larger balloon is to be employed, the previous balloon must be retracted over a guidewire and the next balloon advanced thereover.

[0006] An endovascular procedure is schematically illustrated in Figs. 1 a to 1 d in the case of a partial occlusion, performed by passing a guide 31 axially into and along a vessel (an artery) 14 to the point of the stenosis or obstruction 15 (Fig. 1 a). The nowadays used guides 31 are 0.035 to 0.014 mm in diameter. By pushing the guide 31 through the stenosis or obstruction 15 it is often possible to get beyond the lesion and reach the healthier lumen of the vessel 14 (Fig. 1 b). In this case, a balloon-catheter 25 is axially loaded on the guide 31 to the stenosis 15 and the lesion is dilated (Fig. 1 c). After dilation, and according to the circumstances, a stent (not shown) can be opened in the dilated segment. The stent avoids a rapid restenosis due to the elastic recoil of the vascular wall. Sometimes, if the atherosclerotic stenosis 15 is complete (total occlusion), the guide 31 rests against the lesion, gets stuck, flaps or turns itself in the proximal direction (Fig. 1 d).

Summary

[0007] The present invention concerns a device aimed to allow the perforation of an obstructive arterial atheroma, the possibility to reach the arterial lumen beyond the damaged segment, send a guide in this more healthy artery, coaxially advance a balloon in the perforated atheroma and dilate this arterial segment.

[0008] More particularly, the present invention concerns a catheter for opening an obstruction in a body vessel, the catheter comprising a distal portion having a rotatable boring element comprising a screw thread, the boring element being arranged upon rotation to draw itself distally into the obstruction; and a shaft portion extending between the distal portion and a proximal portion; wherein the shaft portion comprises a hand- rotatable knob system such that the rotation of the knob applies a rotational torque in the desired direction to the shaft portion, which is, in turn, transmitted to rotate the boring element as desired; and wherein the screw thread has a pitch between 0.5 mm and 5 mm.

[0009] In an embodiment, the catheter comprising an expandable dilation member coupled to the boring element so as to be drawn by the rotating boring element towards or into the obstruction.

[0010] The present invention further pertains to a method for opening an obstruction in bodily vessel, comprising:

providing the catheter using the catheter comprising the expandable dilation member;

inserting the catheter in the vessel up to the vascular obstruction; screwing the boring element into the obstruction by hand rotating the knob system until the boring element has completely traversed the obstruction and the expandable dilation member is adjacent to the obstruction; and

expending the expandable dilation member such as to create a lumen.

[0011] The catheter described herein allows for opening an obstruction in a body vessel on a length up to several tenths of centimeters. Due to the screw thread pitch and being operated manually with the hand-rotatable knob system, the catheter is particularly well adapted to perform the obstruction opening in curved vessels.

[0012] The catheter comprising the expandable dilation member allows performing the drilling of the obstruction with the boring element and creating a lumen with the expandable dilation member in a single step.

Brief Description of the Drawings [0013] The invention will be better understood with the aid of the description of an embodiment given by way of example and illustrated by the figures, in which: Figs. 1 a to 1 c illustrate an endovascular procedure comprising the steps of passing a guidewire axially into and along a vessel to the point of the stenosis (Fig. 1 a), pushing the guidewire through the stenosis (Fig. 1 b), and dilating a balloon-catheter on the guidewire (Fig. 1 c);

Fig. 1 d shows the guidewire resting against the stenosis;

Fig. 2 illustrates a catheter comprising a boring element and an expandable dilation member, according to an embodiment;

Fig. 3 illustrates method for using the catheter during a step where the boring element is drilling through an obstruction, according to an embodiment;

Fig. 4 illustrates method during a step where the expandable dilation member is expended, according to an embodiment;

Figs. 5 to 10 shows different possible configurations of screw threads of the boring element;

Fig. 1 1 represents screw threads, according to an embodiment;

Fig. 12 shows the catheter, according to another embodiment;

Fig. 13 represents a shaft portion of the catheter, according to another embodiment; and

Fig. 14 represents the catheter held in a coaxial smooth sheath, according to an embodiment.

Detailed description of possible embodiments

[0014] Fig. 2a shows a catheter 10 according to an embodiment. The catheter 10 comprises a distal portion 1 1 comprising a rotatable boring element 21. The boring element 21 comprises a screw thread 22 and is arranged to rotate and draw itself distally into an obstruction in a body vessel.

[0015] The catheter 10 further comprises a proximal portion 12 comprising a hand-rotatable knob system 23. A shaft portion 26 extends between the boring element 21 and a knob system 23. The rotation of the knob system 23 applies a rotational torque in the desired direction to the shaft portion 26, which is, in turn, transmitted to rotate the boring element 21 as desired. The shaft portion 26 is preferably a high torque shaft portion 26. [0016] Figs. 5 to 10 show different possible configurations of the screw thread 22 of the boring element 21. Put names?

[0017] In an embodiment, the screw thread 21 has a pitch P between 0.5 mm and 5 mm. Here, the pitch P corresponds to the distance between two successive threads. Fig. 2b is a schematic representation of the screw thread 21 showing the pitch P.

[0018] In particular, the diameter of the screw thread 21 can be larger than the diameter of the shaft portion 26 (see for example Figs. 5-7 and 9). The maximum diameter of the screw thread 22 can be equal to the diameter of the shaft portion 26 (Fig. 10). In an embodiment, the minor diameter D _m in of the screw thread 21 is greater than the diameter D26 of the shaft portion 26.

[0019] Preferably, the ratio of the major diameter D _m aj of the screw thread 21 to the diameter of the shaft portion 26 is between 1.3 and 3.

[0020] In other embodiments, the screw thread 21 can have a thread depth d between 0.2 mm and 1 mm or between 0.4 and 0.6 mm (Figs. 6 and 8). Here the thread depth d is defined as the difference between the major diameter Dmaj of the screw thread 21 and the minor diameter D _m in of the screw thread 21 (see Fig. 2b). The screw thread 21 can have a thread angle between 120° and 15°. More particularly, the screw thread 21 can have a thread angle between 80° and 20° or between 40° and 20°.

[0021 ] In yet other embodiments, the screw thread 22 can be

substantially cylindrical, such as illustrated in Figs. 5-8 and 10, or can be tapered, such as illustrated in Fig 9. [0022] The different configurations of the screw thread 22 can be selected according the presumed hardness of the atheroma (obstruction) 15. For example, a large screw thread 22, e.g., screw threads 22 having a pitch that is between 0.3 mm and 4 mm and/or having a thread depth d between 0.4 mm and 0.6 mm, can be advantageous for a hard atheroma. A small screw thread 22, e.g., screw threads 22 having a pitch that is between 0.2 mm and 3 mm and/or having a thread depth d between 0.2 and 0.5 mm, can be advantageously used for a softer atheroma.

[0023] In an embodiment, the screw thread 21 has a thread depth d between 0.2 mm and 1 mm, or between 0.4 and 0.6 mm (corresponding to the M 1.6 and M 18 ISO 261 standard, respectively).

[0024] In another embodiment, the boring element 21 has a length between 1 cm and 3 cm.

[0025] In yet another embodiment represented in Fig. 1 1 , the screw thread comprises a succession of elements 22' articulately connected (for example intersliding with each other) on one another such that the boring element 21 can be bent.

[0026] In yet another embodiment represented in Fig. 13, the shaft portion 26 comprises a succession of elements 26' articulately connected on one another.

[0027] The screw thread elements 22' and/or the shaft portion elements 26' are interconnected in such a way that they can bend one on the following element with the torsional movement of one element being integrally transmitted to the next element. The succession of articulated elements 22', 26' are further arranged such that the rotational torque applied by the rotation of the knob system 23 is fully transmitted to rotate the boring element 21 as desired.

[0028] The elements 22', 26' can be made from a metal or a plastic. Each of the elements 22', 26' can comprise a canal portion 24' (see also Fig. 14) such as to provide the hollow canal 24 when all the elements are assembled to for the boring element 21 and/or the shaft portion 26.

[0029] In a variant shown in Fig. 12, the catheter 10 can further comprise a traction wire 35 attached at a distal end 34 of the boring element 21. The traction wire 35 can be pulled in the proximal direction such as to bend the boring element 21. The traction wire 35 can be arranged slidingly within a wire canal 32 extending along the distal and proximal portions 1 1 , 12. The traction wire 35 can extend asymmetrically along the distal and proximal portions 1 1 , 12. [0030] When the obstruction is located on a curved vessel segment (for example, the proximal popliteal artery), the articulated screw thread elements 22' and the articulated shaft portion elements 26' can be easily bent by pulling the traction wire 35. In the case only the screw thread elements 22' are articulated, pulling the traction wire 35 will allow bending the boring element 21 initiate as to initiate curve of the vessel.

[0031] The atheromatous obstruction 15 can have a variable non homogeneous consistency. In some place it can be calcified and very hard, in another place it can be softer. During the rotational movement of the knob system 23, the boring element 21 can encounter a hard segment of the obstruction and can be diverted from this stony localized hardness and sink into a softer segment. In the case where the obstruction 15 is located at the beginning of a curved vessel segment (for example, the proximal popliteal artery), the articulated screw thread elements 22' can be bent to a proper position by pulling on the traction wire 35. [0032] In an embodiment represented in Fig. 14, the catheter 10 is held in a in a coaxial smooth sheath 36. The smooth sheath 36 protects the vessel wall from eventual lesions caused by the unprotected screw threads 22. Thus the screw threads 22 protected by the sheath 36 can safely reach the obstruction 15. The sheath 36 can be removed once the boring element 21 has started drilling into the obstruction 15. [0033] The catheter disclosed herein allows for opening an obstruction in a body vessel on a length up to several tenths of centimeters. Due to the screw thread pitch and the fact that the catheter is being operated manually with the hand-rotatable knob system, the catheter is particularly well adapted to perform the obstruction opening in curved vessels. This is particularly important in sclerosed vessels where the curves tend to be accentuated in comparison to healthy vessels. By using the manual operation, the catheter can be advanced in the vessel at a slow speed. The advancing speed can be easily adapted depending on the portion of the vessel that the catheter has reached. For example, the obstruction can have various consistencies and adapting the advancement speed of the catheter allows for the boring portion 21 to remains in the obstruction and not deviate towards the vessel wall. The progression of the catheter within the vessel can be monitored by using visual means such as radioscopic (X-ray) control.

[0034] Different catheter 10 having screw thread pitch can be selected to perform an obstruction opening operation depending on the local obstruction conditions of the vessel.

[0035] In an embodiment, the distal portion 1 1 of the catheter 10 comprises an expandable dilation member 25. The dilation member 25 can be coupled to the boring element 21 so as to be drawn by the rotating boring element 21 towards or into the obstruction.

[0036] The length of the screw thread 22 can be at least equal than the length of the expandable dilation member 25. Alternatively, the length of the screw thread 22 can be smaller than the length of the expandable dilation member 25.

[0037] A method for using the catheter 10 comprising the dilation member 25 is illustrated in Figs. 3 and 4, according to an embodiment. In particular, a guidewire 31 is entered into the vessel 14, towards the vascular obstruction 15, until it contacts the obstruction 15. The catheter 10 is then inserted coaxial around the guidewire 31 and introduced into the vessel 14 up to the vascular obstruction 15.

[0038] To this end, the catheter 10 can comprise a hollow canal 24 coaxial with the shaft portion 26 and the boring element 21. The guidewire 31 can then be freely movable into the hollow canal 24. Thus, the center of the catheter 10 comprises an axial hollow canal 24 allowing the passage of the guidewire 31 to the obstruction 15 and beyond it after the screwing movement of the boring element 21.

[0039] The boring element 21 is then screwed in the obstruction 15 by hand rotating the knob system 23. During rotation, the boring element 21 penetrates and drills through the obstruction 15, creating a passage in the obstruction 15 (see Fig. 3). The knob system 23 is rotated until the boring element 21 has crossed the obstruction 15 completely and the expandable dilation member 25 is adjacent to the obstruction 15. The expandable dilation member 25 is then expended such that create a lumen 16 crossing the obstruction 15 such as to reestablish the flow in the vessel 14 (see Fig. 4). The expandable dilation member 25 can comprise a inflation balloon, a stent or any suitable dilatation member.

Reference Numbers

10 catheter

1 1 distal portion

12 proximal portion

14 artery

15 obstruction

16 lumen

21 boring element

22 screw thread

22' articulated screw thread element

23 knob system

24 hollow canal

24' canal portion

25 expandable dilation member

26 shaft portion

26' articulated element of the shaft portion

31 guidewire

32 wire canal

34 distal end

35 traction wire

36 smooth sheath

d thread depth

D26 diameter of the shaft portion

Dmaj major diameter

Dmin minor diameter

P pitch