WO2016203040A1

WO2016203040A1 - Endoluminal vascular prostheses and method of deploying such prostheses

Info

Publication number: WO2016203040A1
Application number: PCT/EP2016/064166
Authority: WO
Inventors: Patrick Berg; Victor Charles BERG
Original assignee: Benta Pharma Industries
Priority date: 2015-06-18
Filing date: 2016-06-20
Publication date: 2016-12-22
Also published as: EP3310299A1

Abstract

The present invention relates to endoluminal vascular prostheses and methods of deploying such prostheses. More particularly this invention relates to systems, apparatuses and methods for deploying stents and/or stentgrafts and creating fenestrations in such devices while they are deployed in situ within body lumens, such as blood vessels, to provide additional flow pathways and/or join with other flow‐directing or structural devices. It is the object of the invention to provide a flexible endovascular device implanted in the aorta with a self‐expandable stent allowing blood flow through the struts during implantation and during cannulation and connection of target vessels with the aortic lumen by the use of stentgrafts. After connection of all the target vessels, the residual lumen between aortic wall and aortic stent is sealed with polymer‐filled endobags.

Description

Endoluminal vascular prostheses and

method of deploying such prostheses

1. FIELD OF THE INVENTION

The present invention relates to endoluminal vascular prostheses and methods of deploying such prostheses. More particularly this invention relates to systems, apparatuses and methods for deploying stents and/or stentgrafts and creating fenestrations in such devices while they are deployed in situ within body lumens, such as blood vessels, to provide additional flow pathways and/or join with other flow-directing or structural devices.

2. BACKGROUND OF THE INVENTION

In the following we refer to a list of references at the end of the description.

An aortic aneurysm is characterized by the dilation of the wall of the aorta. Aortic aneurysms are likely to rupture, especially when the diameter increases, thus posing significant danger to the patient. Rupture of an aneurysm gives only a 20 % chance of survival, so there is a significant emphasis placed on early diagnosis and treatment. (1)

Aneurysms of the abdominal and thoracic aorta are a major cause of mortality, especially in the western societies. With an

increasingly ageing society, the incidence of aneurysm, particular abdominal aortic aneurysm, continues to rise.

Surgical repair of aneurysm is a major and invasive undertaking and there has been much effort in developing less invasive methods. Endovascular repair of aneurysms, using stentgrafts, is now accepted the method of choice(2). Stentgrafts are medical devices constructed to reinforce, replace, or bridge a part of a damaged, unhealthy, or diseased blood vessel. The technique has significant limitations and is nor suitable for all patients.

Hostile neck anatomy has been described with higher rates of early (intraoperative) type I endoleak and intervention (3)(4)(5). Off-label use of a stentgraft is associated with a greater risk of type I

endoleak. (6)(7)(8).

The difficulty of using a stentgraft at or near an intersection of an artery to be repaired (such as the aorta) with branch vessels (for example the renal arteries, superior mesenteric artery, celiac trunk, brachiocephalic artery, carotid arteries or left subclavian artery etc.) is well recognized.

Moreover, the numerous anatomic variations of the visceral arteries make it impossible to use a ready-to-use stentgraft.

(9)(10)(11)(12)(13)

For such patients, endovascular repair is only possible using unique, individually designed and manufactured endografts having

appropriate branch grafts or fenestrations, which match the patient's anatomy. Whilst such grafts can be obtained

commercially, for example the Zenith device of COOK (14)(15) or the fenestrated Anaconda graft from VASCUTEK (16), the

meticulous design of such grafts is reliant on accurate preoperative imaging data.

Procedures with custom-made fenestrated stentgrafts are

technically challenging and require a long learning curve. Moreover the use of patient-specific designed grafts is expensive and requires significant pre- planning so that such grafts are not available in emergency situations.

Proof of concept for off-the-shelf fenestrated devices (VENTANA fenestrated system, COOK Zenith p-branch) for the endovascular repair of juxtarenal and pararenal aortic aneurysms in selected patients has been demonstrated. But nearly 40% of juxtarenal or pararenal aneurysms do not meet anatomical criteria for

endovascular repair using one of the two devices, justifying need for additional designs (17).

The use of parallel "chimney" grafts has been described to treat juxta- and pararenal aneurysms. (18)(19)(20)(21)(22).

This technique is easier than the technique for fenestrated

stentgrafts. Treatment of emergency cases is possible. However there is a higher leak rate (5-15%) compared to fenestrated

stentgrafts (2-5%). The use of chimney grafts in conjunction with polymer-filled endobags which have the ability to conform to adjacent structures may offer advantages over conventional endografts when combined with parallel grafts designed to treat juxtarenal aneurysms (23).

The desirability of conducting in vivo (in situ) fenestration of a graft has been recognized (24). McWilliams describe the fenestration of a thoracic graft by passing a guide wire down the branch artery to pierce the fabric of the graft and then expanding the hole formed by inflation of a balloon. However, whilst the technique described shows that in situ fenestration is possible, it requires percutaneous retrograde access to the branch vessel for correct location of the fenestration. Such is possible for branches of the aortic arch (25) but not for visceral vessels such as the renal or mesenteric arteries. Retrograde Fenestration for visceral vessels has been described before (26) but only in animal experiments. An alternative approach is to puncture the graft fabric in an antegrade fashion. Such a technique has been described using radiofrequency based apparatus (27), needle puncture of bloused section (28)(29)(30), magnetic location and needle puncture (31), needle puncture (32), piercing catheter (33), stent (34), steerable catheter and puncture (35), temporary„chimney" (36) or

sidebranch stentgraft (37).

The requirements for in vivo fenestration are : obtention of low leak rates, a technique easy to learn and to perform, no wait time using off-the-shelf devices, possibility to treat emergent cases, ostium of target vessels have to be marked easily and

cannulated without difficulty, ischemia due to temporary occlusion of target vessels has to be prevented and the stentgraft should be flexible enough to deal with a tortuous anatomy. It is the object of the invention to provide a flexible prosthesis with a self- expandable stent allowing blood flow through the struts during cannulation and connection of target vessels with the aortic lumen by the use of stentgrafts. After having connected all the target vessels, the residual lumen between aortic wall and aortic stent is sealed with polymer-filled endobags.

3. SUMMARY OF THE INVENTION

3.1. Stent System According to the invention, the self-expandable stent is cylindrical in shape. An oblique plane cuts the proximal end of the cylinder. As the cutting plane is not perpendicular to the axis, the section is an ellipse. The lowest part is meant to be used in an anterior position, below a visceral target vessel, either superior mesenteric artery or celiac trunk for example.

Depending on the angle (β) of the cutting of the stent, the height of the dorsal part of the stent extends the height of the ventral part by the value of the diameter of the stent multiplied by tangent of β: h2-hl= d*tan( ), where d = diameter of the stent.

The Stent System consists of a closed end, braided self-expanding stent made of Nitinol (nickel-titanium alloy) wire material that is premounted on a delivery system. The over-the-wire (OTW) stent delivery system is compatible with a 0.035" guide wire. The stents contain radiopaque markers at each end and antero-posteriorly allowing to identify the rotation. It also contains a marker at the lowest part of the ellipse. This marker should be placed under the visceral vessel serving as reference.

The stent is contained within the outer sheath of the delivery system. Once the distal end of the delivery system reaches the treatment site, the outer sheath of the delivery system is retracted to expose the stent and start its self-expansion.

The Vascular Stents are designed to open to a pre-programmed diameter at body temperature. The diameter of the stent is inferior to the diameter of the aorta. The stent remains attached to the catheter allowing minor rotation and height adjustment during implantation.

The stent diameter should be chosen according to the diameter of the aortic segment to treat. The difference between aortic and stent diameter should be sufficient to place a parallel graft outside the stent in case of technically difficult access or a target vessel out of reach for an antegrade fenestration. This might occur when the ostium of the target vessel to treat is superposed by the proximal endobag or when the height of the ostium is lower than the portion to fenestrate from the stent system.

3.2. Endobags

Several thin guide wires are fixed on the proximal outer part of the stent. Over these wires, contained endobags can be advanced over the guide wires up to the height of the stent. The endobags are contained in a catheter and released by pulling down the catheter. The endobags are staying connected by small feeder pipes allowing the polymer fill. These endobags are in a longitudinal position at 45°, 135°, 225° and 315°

One endobag is attached to the two proximal rings end of the stent following the elliptic shape. This endobag is also connected to a feeder pipe outside the stent allowing polymer fill.

When the endobags are filled with polymer, the space between aortic wall and stent system around the connected stentgrafts is sealed.

Once the polymer has hardened the connecting pipes with the thin wires will be pulled out.

The advantage of using endobags not primarily fixed to the stent is to reduce the size of the stent system and to prevent access obstruction to target vessels during cannulation and fenestration.

3.3. Fenestration The free space between the interwoven nitinol wires has the form of a rhombus. Per definition, a rhombus is a parallelogram with a 4- sided flat shape with straight sides where all sides have equal length and all opposite sides are parallel and opposite angles are equal.

This free space is used to cannulate a target vessel with a guide wire. Once all the target vessels are cannulated, a stentgraft is advanced over the guide wire into the target vessel. The distal part of the stentgraft is delivered in the proximal part of the target vessel, the proximal part of the stentgraft is delivered in the aortic lumen inside the self-expandable stent. The distance between proximal end of the stentgraft and the rhombus-like wires of the stent is dilated and slightly oversized, preventing a dislocation between stent and connecting stentgraft during manipulations.

A technical issue could be to safely cannulate the non-covered stent to create the fenestrations either from the contralateral side or by a subclavian/brachial approach. The fact of matter is, while trying to cannulate the stent with a wire, the wire could go through the struts and jeopardize the procedure. To prevent this, a preloaded contralateral wire will be used and allow to advance an introducer sheath from the contralateral side without any difficulties. For the subclavian/brachial approach the guide wire used to advance the stent system will be catched by a snare catheter from the

subclavian/brachial approach and a long introducer sheath will be introduced from above over this wire. The end of the introducer sheath will be placed into the self-expandable stent.

3.4. Planning

During planning of the procedure it is mandatory to calculate the distances between the different vessels to treat so as the angles of ostia of the vessels. If for instance the stent should be placed below the superior mesenteric artery, the lowest part of the vessel and the angle will be the center of a new coordinate system thus giving this point the coordinates (0;0). Thus the lowest part of the elliptic ring will have the coordinates (0;-3) due to the fact that a minimum of 3 mm as safe distance should be respected. The ostia of the renal arteries will be projected on the graph giving for x the value for the angle difference between the center of the SMA and the renal arteries. The value for y is the distance between the bottom of the SMA and the top of the renal arteries. If the stent is planned to be deployed between the celiac axis and the SMA, the bottom of the celiac axis will have the coordinates (0;0) and all other coordinates will be calculated as described before in this coordinate system. A drawing of the unwrapped cylinder can be done. The ellipse will then have the shape of a sinus curve with period nr and the

formula: f(x)= a*(l-cos(x/r)), where a is the amplitude ((h2-hl)/2) and x the angle difference of the vessel to treat in relation to the SMA with the coordinates (0;0) and r the radius of the stent.

3.5. Additional procedures

Once all the vessels fenestrated and endobags filled, the stent system is released. An existing device to treat infrarenal aortic aneurysms may be attached to the distal part of the stent system, thus completing the procedure.

3.6. Summary

- The stent graft system is introduced over a guide wire

with a contralateral preloaded wire and positioned below the reference target vessel.

- The stent is released but the stent will stay attached to the stent system to allow rotation and height adjustments.

- An introducer sheath is introduced over the preloaded contralateral wire into the stent. The target vessel to fenestrate is cannulated through the struts of the stent with a guide-wire and a diagnostic catheter.

- A covered stent is introduced into the target vessel

through the struts, the proximal part staying inside the stent and overdilated to prevent dislocation.

- Contained endobags are advanced over preloaded wires up to the proximal end of the stent where another endobag is attached to the proximal ring following the elliptic shape.

- All endobags are filled with polymer.

- The stent is finally released completely and the

procedure is finished by attaching to the device a traditional stentgraft.

- A parallel graft may be performed prior to polymer fill outside the stent system in particular cases where a direct fenestration is not possible.

4. BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention can be derived from the following description which explains the invention in more detail on the basis of embodiments in connection with the enclosed Figures, wherein:

Figure 1 shows a perspective view of the over-the-wire

(OTW) stent delivery system compatible with a 0.035" guide wire. Figure 2 shows a perspective view of the self expandable stent.

Figure 3 shows a lateral sketch of the stent.

Figure 4 shows the unwrapped cylinder.

Figure 5 shows the proximal endobag.

Figure 6 shows the lateral endobag.

Figure 7 shows the four lateral endobags.

Figure 8 and 9 show the fenestration with a stentgraft through the rhombus of the stent.

Figure 10 planning of a procedure with projection of the ostia of celiac trunk, superior mesenteric artery, left and right renal artery.

5. DETAILED DESCRIPTION OF THE

INVENTION

Figure 1 shows a perspective view of the over-the-wire (OTW) delivery system, respectively, of a first introducer sheath 4 that glides over a guide wire 1 with a diameter of e.g. 0.035". The first introducer sheath 4 contains a dilator 3. A contralateral wire 2 is attached to the stent system allowing to cannulate the stent system from the contralateral side. The stent 5 is contained within the introducer sheath.

Figure 2 shows a perspective view of the self expandable stent 5. The self- expandable stent is cylindrical in shape. An oblique plane cuts the proximal end of the cylinder. As the cutting plane is not

perpendicular to the axis, the section is an ellipse.

Figure 3 shows a lateral sketch of the stent. Depending on the angle (β) of the cutting of the stent, the height of the dorsal part of the stent extends the height of the ventral part by the value of the diameter of the stent multiplied by tangent of β: h2-hl= d*tan( ), where d = diameter of the stent.

Figure 4 shows the unwrapped cylinder. The ellipse will then have the shape of a sinus curve with period nr and the formula: f(x)=a*(l-cos(x/r)), where a is the amplitude ((h2-hl)/2) and r the radius of the stent. Two proximal rings 6 and 7 are fixed to the mesh. The proximal endobag is fixed on the two rings. Four radiopaque markers 8 are fixed on the mesh. The upper marker is fixed on the proximal ring at 0°. Two other markers are fixed on the ventral part of the stent and another marker at 180°. While implanting the stent, the upper marker delivers the information of the height of implantation. The three others deliver the information of rotation of the stent. Under fluoroscopy the three markers should be placed on a line.

Figure 5 shows the proximal endobag. This endobag is attached to the two proximal rings end of the stent following the elliptic shape. This endobag is also connected to a feeder pipe outside the stent allowing polymer fill. Figure 6 shows the lateral endobag. A thin guide wire 10 is fixed on the proximal outer part of the stent. Over this wire, a contained endobag 11 can be advanced over the guide wires up to the height of the stent. The endobags are contained in a catheter 12 and released by pulling down the catheter. The endobag is connected by small feeder pipe 13 allowing the polymer fill.

Figure 7

Four endobags in total are placed in a longitudinal position at 45°, 135°, 225° and 315°

Figure 8 and 9

The free space between the interwoven nitinol wires 14 has the form of a rhombus. The target vessel is cannulated through this spacel with a guide wire. A stentgraft 15 is advanced over the guide wire into the target vessel. The proximal part of the stentgraft is delivered in the aortic lumen inside the self-expandable stent and is dilated and slightly oversized 16, preventing a dislocation between stent and connecting stentgraft during manipulations.

Figure 10 example of procedure planning:

Bottom SMA: Coordinates (0;0) diameter 7 mm

Celiac Axis (CA) : +15° to SMA, diameter 9 mm, distance CA-SMA 12 mm

Right renal artery: -67° to SMA, diameter 6 mm, distance to SMA 8 mm Left renal artery: +75° to SMA, diameter 6 mm, distance to SMA 3 mm tent radius 11 mm. Angle β 30° safety distance bottom SMA proximal ring 3 mm

The stent system consists of a closed end, braided self- expanding stent made of Nitinol 5 (nickel-titanium alloy) wire material that is premounted on a delivery system. The over- the-wire (OTW) stent delivery system is compatible with a 0.035" guide wire 1.

The stent system has a diameter inferior of the diameter of the aorta. The stent remains attached to the catheter allowing minor rotation and height adjustment during implantation.

The stent system further comprises a proximal end cut in an oblique plane antero-posteriorly transforming the section in an ellipse.

The stent system further comprises a contralateral preloaded wire 2 allowing cannulation of the stent without difficulties.

The stent system further comprises four radiopaque markers 8, allowing height and rotation control.

The stent system has two proximal rings 6 and 7 with an elliptic shape.

The stent system furthers compries an endobag 9 which is mounted on the two proximal rings. The endobag furthers compries a feeder pipe 13 which allows polymer fill and sealing of the proximal rings.

The stent system furthers compries four thin guide wires 10 which are fixed outside the stent system to the proximal rings at 45°, 135°, 225° and 315°.

The stent system furthers compries four lateral endobags 11 which are advanced over the guide wires 10 to the proximal end of the stent. Feeder pipes 13 allow polymer fill of the endobags.

The free space between the interwoven nitinol wires 14 has the form of a rhombus.

Method for fenestrating a stentgraft 5 located in a blood vessel, which branches into a branch vessel, comprising the following step: the target vessel is cannulated through the struts of the stent system with a guide wire and a stentgraft is advanced over this guide wire into the target vessel.

The method may further comprise the step: the proximal part of the stentgraft 15 is placed inside the mesh of the stent 14 and overdilated 16 to prevent dislocation.

The method may further comprise the step: polymer fill of the endobags seals the space between the stent system and the aortic wall around the connecting stentgrafts.

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Claims

7. PATENT CLAIMS

1. A stent system comprising a closed end, braided self- expanding stent made of a wire material wherein the stent is premounted on a delivery system.

2. The stent system according to claim 1, wherein the stent is made of a nickel-titanium alloy, especially Nitinol 5.

3. The stent system according to claim 1 or 2, wherein the over- the-wire (OTW) stent delivery system is arranged such that it is compatible with a 0.035" guide wire (1).

4. The stent system according to one of the preceding claims, wherein the stent system has a diameter inferior of the diameter of the aorta.

5. The stent system according to one of the preceding claims, wherein the stent system is arranged such that the stent remains attached to a catheter allowing minor rotation and height adjustment during implantation.

6. The stent system according to one of the preceding claims, further comprising a proximal end cut in an oblique plane antero-posteriorly transforming the section in an ellipse.

7. The stent system according to one of the preceding claims, further comprising a contralateral preloaded wire (2) allowing cannulation of the stent.

8. The stent system according to one of the preceding claims, further comprising four radiopaque markers (8) for height and/or rotation control.

9. The stent system according to one of the preceding claims, wherein the stent system has at least one proximal ring, preferably two proximal rings (6, 7), with an elliptic shape.

10. The stent system according to claim 9, wherein an endobag (9) is mounted on the two proximal rings (6, 7).

11. The stent system according to claim 9 or 10, wherein a feeder pipe (13) allows polymer fill and sealing of the proximal rings (6, 7).

12. The stent system according to one of the preceding claims, wherein four thin guide wires (10) are fixed outside the stent system to the proximal rings (6, 7).

13. The stent system according to claim 12, wherein four thin

guide wires (10) are fixed to the proximal rings with a distance of 90° to one another, especially at 45°, 135°, 225° and 315°.

14. The stent system according to claim 12 or 13, wherein four lateral endobags (11) are advanced over the guide wires (10) to the proximal end of the stent.

15. The stent system according to claim 14, wherein at least one feeder pipe (13) for filling the endobags (11) with a polymer is provided.

16. The stent system according to one of the preceding claims, wherein the free space between the interwoven wires (14) of the stent has the form of a rhombus.

17. Method for fenestrating a stentgraft (5) located in a blood vessel, which branches into a branch vessel, comprising the following step:

- cannulating the target vessel through the struts of the stent system with a guide wire, and

- a advancing the stentgraft (15) over this guide wire into the target vessel.

18. Method according to claim 17, further comprising the step: placing the proximal part of the stentgraft (15) inside the mesh of the stent (14) and overdilating the proximal part of the stentgraft to prevent dislocation.

19. Method according to claim 17 or 18, further comprising the step: filling endobags with a polymer to seal the space

between the stent system and an aortic wall around the connecting stentgrafts.

20. Method according to one of the claims 17 to 19, wherein in case a target vessel cannot be cannulated through the struts, a parallel graft outside the stent system is placed and sealed according to the step of claim 19.