WO1999034748A1

WO1999034748A1 - Implantable band and stent graft for treating a vessel aneurysm

Info

Publication number: WO1999034748A1
Application number: PCT/IB1999/000118
Authority: WO
Inventors: Leonard Pinchuk
Original assignee: Boston Scientific, Limited
Priority date: 1998-01-07
Filing date: 1999-01-07
Publication date: 1999-07-15

Abstract

This invention is a structure for treating an aortic aneurysm having a dilated vessel portion (26) adjacent to a relatively healthy neck portion (27). The structure includes a band (40) having opposite ends and a stent or stent graft (42). The band (40) is wrapped tightened around the outer circumference of the neck portion (27) at a location adjacent to the dilated portion, and its ends engaged to secure the band (40) in place. The stent or stent graft (42) can be implanted in the neck and aneurysm before or after the band (40) is implanted. The band (40) prevents dilation of the neck and migration of the stent or stent graft (42).

Description

IMPLANTABLE BAND AND STENT-GRAFT FOR TREATING A VESSEL ANEURYSM

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to devices and methods for treating diseased vessels in the human body In particular, the present invention is an implantable band and stent-graft to treat an aneurysm in a vessel

Description of the Related Art

Medical prostheses frequently referred to as stents and stent-grafts are well known and commercially available These thin walled, tubular, devices are used within body vessels of humans and other animals for a variety of medical applications Stents and stent-grafts are, for example, used to repair (1 e , treat) aneurysms, enlarged (1 e , dilated) diseased and weakened areas of a vessel Stenosis, a narrowing and occlusion of a vessel typically caused by tissue buildup, also is often treated by stents and stent-grafts A relatively healthy and undilated portion of the vessel, sometimes referred to as the neck, is often located adjacent to the weakened portion with the aneurysm

One type of aneurysm which can be treated by stents and stent-grafts is known as an abdominal aortic aneurysm Abdominal aortic aneurysms typically occur in the portion of the aorta between the renal artery branch (1 e , the location at which the renal arteries meet the aorta) and the iliac bifurcation (1 e , the location downstream from the renal artery branch at which the aorta divides into the iliac arteries) An aortic graft for repairing an abdominal aortic aneurysm is disclosed in the Parodi U S Patent 5,591,229

Stents and stent-grafts are typically intraluminally delivered to the site of an aneurysm in a reduced-diameter state After being positioned adjacent to the aneurysm, the stent or stent-graft is radially extended into an expanded state, often by self expansion and/or by an inflatable balloon One or both ends of the stent or stent- graft will typically be positioned adjacent to or over the relatively healthy portions of the vessel In the expanded state, these portions of the stent or stent-graft will engage the circumference of the interior surface of the relatively healthy portions of the vessel If the weakened portion of the vessel with the aneurysm has a diameter which is greater than the diameter of the stent or stent-graft in its expanded state, the portion of the stent or stent-graft extending through the aneurysm will essentially float in the vessel, secured in place by the ends of the stent or stent-graft engaged with the relatively healthy portions of the vessel Additional anchoring support for the stent- graft is provided by the ingrowth of tissue into the stent-graft following implantation, and/or by attached hooks

There are times, however, when following implantation of the stent-graft the patient's aneurysmal disease progresses, resulting in weakening and/or dilation of what was previously the relatively healthy portions of the vessel During this progression of the aneurysmal disease, an implanted stent-graft can often dilate with the vessel to a limited extent However, if the aneurysmal disease progresses to a relatively large degree and/or the stent-graft is not ingrown with tissue, the stent-graft can become dislodged, slip and migrate from its initially-implanted position This post-implantation movement of the stent-graft can be detrimental to the performance of the device, and result in harm to the patient

There is, therefore, a continuing need for improved devices and methods for treating diseased vessels A device and method for enhancing the efficacy of known stent and stent-graft treatment approaches would be especially desirable The efficiency of health care services involving any such improved device would be enhanced if the device can be implanted by minimally invasive surgical techniques

SUMMARY OF THE INVENTION

The present invention is a structure for treating a section of a patient's vessel having a first weakened vessel portion adjacent to a second relatively healthy vessel portion The structure includes a band having first and second free opposite ends, and a radially expandable stent or stent-graft The band is wrapped and tightened around the outer circumference of the healthy vessel portion, and the first and second ends engaged with one another to secure the band to the outer circumference of the healthy vessel portion The stent or stent-graft is implanted in the section of the patient's vessel The implanted stent or stent-graft extends through at least a portion of the weakened vessel portion and engages an inner circumference of the healthy vessel portion at a location adjacent to the weakened vessel portion The band helps prevent dilation of the healthy vessel portion and migration of the stent or stent-graft In addition to enhancing the efficacy of implanted stents and stent-grafts, the band can be efficiently implanted by minimally invasive surgical procedures Furthermore, the band can be implanted at the time that the stent-graft is implanted, or months or even years later

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an illustration of a portion of an aorta with an aneurysm, which can be treated by the device of the present invention

Figure 2 is an illustration of the portion of the aorta shown in Figure 1, having a band secured to the neck of the aneurysm in accordance with the present invention

Figure 3 is an illustration of the portion of the aorta shown in Figure 1, with portions thereof shown in section, and illustrating a band and a stent-graft implanted in accordance with the present invention

Figure 4 is an illustration of the portion of the aorta shown in Figure 1, with portions thereof shown in section, illustrating two bands and a stent-graft implanted in accordance with the present invention

Figure 5 is a detailed illustration of a first embodiment of the band shown in Figures 2 - 4

Figure 6a is a detailed illustration of a second embodiment of the band shown in Figures 2 - 4, in its unfastened state

Figure 6b is a detailed illustration of the band shown in Figure 6a in its fastened state

Figure 7 is a detailed illustration of a third embodiment of the band shown in Figures 2 - 4 Figure 8 is a detailed illustration of a fourth embodiment of the band shown in Figures 2 - 4

Figure 9 is a detailed illustration of a fifth embodiment of a band which can be used with the method of the present invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 is an illustration of a diseased abdominal aorta 12 which can be treated by a band and stent or stent-graft in accordance with the present invention As shown, renal arteries 14A and 14B extend from the aorta 12 at renal artery branch 16 Downstream from the renal artery branch 16 is the iliac bifurcation 20 at which the aorta 12 divides or branches into the iliac arteries 18 A and 18B The device and method of the present invention can be used, for example, to treat a section of the vessel including a first or diseased portion 26 which is shown located between the renal artery branch 16 and the iliac bifurcation 20 Diseased vessel portions such as

26 are commonly known as aortic aneurysms Aortic aneurysms are characterized by weakened, and as shown, dilated (I e , expanded-diameter) vessel walls On opposite sides of the diseased portion 26 are second and third relatively healthy vessel portions

27 and 28, respectively The relatively healthy vessel portions 27 and 28 are generally not weakened or dilated to the degree that the diseased portion 26 is weakened and dilated, and are therefore generally stronger than the diseased portion In the portion of aorta 12 shown in Figure 1, second and third vessel portions 27 and 28, also sometimes known as the necks of the aneurysm, are not dilated to a substantial degree

As shown in Figure 2, the method of the present invention includes securing a band 40 around at least one of the relatively healthy vessel portions such as 27 As shown in Figures 3 and 4, the band 40 is secured around and to the outer circumferential surface of the vessel portion 27 and/or 28 at a location adjacent to the inner circumferential surface of the vessel portions engaged by the stent or stent-graft 42 The band 40 can be secured to the vessel portion 27 and/or 28 either before or after a stent or stent-graft 42 is implanted in the diseased vessel portion 26 The implanted band 40 helps slow or prevent further dilation of vessel portions 27 and/or 28, .and thereby reduces or prevents dislodgment or migration of the implanted stent or stent-graft 42

Band 40 can be placed around the vessel portion 27 and/or 28 using known open surgical techniques Preferably, however, the band 40 is placed using minimally invasive surgical techniques Surgical techniques of these types are well known Briefly, using such a technique a surgeon will cut a number of small holes in the patient's abdomen and place a trocar in the holes to provide access for an endoscope (internal viewing instrument) and other surgical instruments The abdomen is then inflated with gas such as carbon dioxide to provide the space required to perform the surgical procedure Using the endoscope and other instruments, the surgeon will dissect the aorta 12 from adjacent tissues and wrap the band around the vessel portions 27 and/or 28 Opposite ends of the band 40 are then engaged, the band tightened to be flush with the vessel portion 27 and/or 28, and the band ends secured The band 40 can also be secured to the vessel portions 27 and/or 28 by staples, sutures or other conventional surgical fasteners (not shown) After the band 40 is implanted and the aorta 12 and the surrounding tissues repositioned, the surgical instruments are removed and the holes sutured closed

A number of different embodiments of bands which can be used in accordance with the present invention are illustrated in Figures 5, 6a, 6b, 7 and 8 The band 140 shown in Figure 5 has a belt buckle-type fastener 150 for connecting its opposite ends 152 and 154 Fastener 150 includes a loop 156 and tongue 158 on the end 152, and a number of adjacent holes 160 on the end 154 After being wrapped around the vessel portion at which it is to be placed, fastener 150 is used in a conventional manner to secure the band 140 in place

The band 240 in Figures 6a and 6b has a fastener 250 formed by a U-shaped hook 258 and a plurality of tubes 256 on the ends 252 and 254 of the band The tubes 256 are transversely mounted to the band 240 During the implantation procedure the band 240 will be cut to the desired length, and the legs of the hook 258 inserted into and preferably locked within the tubes 256 on the ends 252 and 254 (as shown in Figure 6b) to secure the band in place Figure 7 illustrates a band 340 having a fastener 350 which includes buckle loop 356 on its end 352 During implantation the end 354 is placed through loop 356, pulled tight and secured to end 352 by surgical staples 358

A band 440 having a cable tie-type fastener 450 is shown in Figure 8 Any known and suitable cable tie configuration can be used for fastener 450 Fastener 450 includes ratchet member 456 on the end 452 of the band 450, and may have serrations or other structures (not shown) on the end 454 which cooperate with the ratchet member During implantation the end 454 is pulled through ratchet member 456 until the band 440 is tightened around the vessel portion The ratchet member 456 allows the end 454 of the band 440 to move only in the tightening direction, thereby securing the band in place after it has been tightened

The band and its fasteners can be fabricated from any of a variety of suitable implantable materials The band can be impermeable (non-porous), or microporous and formed of braided, woven, non-woven or knitted textile materials Examples of suitable materials include PET, polyurethane, polymethylmethacrylate, polyolefin, polyvinyl chloride, polytetrafluoroethylene (PTFE) and polypropylene Expanded PTFE can also be used Alternative materials include porous polymers such as particle eluted si cone rubber or polyolefin or polyurethane Combinations of the materials described above, and other implantable materials such as stainless steel and other metal alloys, can also be used

Bands 40 and the method described above can be used in connection with most any now known or later-developed stents and stent-grafts Both self-expanding and balloon expandable stents and stent-grafts can be used with the bands 40 and the method of the present invention Examples of self-expandable stents are shown, for example, in the Wallsten U S Patent 4,655,771 and the Wallsten et al U S Patent 5,061,275 which are hereby incorporated by reference in their entirety The stent- grafts can be covered, lined or interwoven with synthetic or textile materials Straight tubular, bifurcated, tapered, modular multiple component and multiple legged devices are examples of types of stent-gr.afts which can have enhanced efficacy when used in connection with the band and method of the present invention Bifurcated stent-grafts are, for example, described in the Alcime et al U S Patent 5,632,772 and the Dereume et al U S Patent 5,639,278 Yet other examples of stent-grafts and covers for use therewith are disclosed in European Patent Publication EP 0 804 934 and the following U S Patents Wong 4,475,972, Pinchuk et al 4,738,740, Pinchuk 5,229,431 and Dereume 5,653,747 All the above identified patent documents are hereby incorporated by reference in their entirety The band and method of the invention can also enhance the efficacy of other implanted stent and stent-graft types of devices such as occlusion devices that can dislodge or migrate if the vasculature in which they are implanted were to dilate or weaken

As described above, the band 40 can be secured to the vessel portion before or after the stent or stent-graft is implanted Any now known or later developed procedure for implanting the stent or stent-graft can be used in connection with the present invention Devices and methods for delivering and deploying stents and stent- grafts are disclosed, for example, in the following U S Patents, all of which are hereby incorporated by reference in their entirety Wallsten et al 4,732,152, Burton et al 5,026,377, Heyn et al 5,201,757 and Braunschweiler et al 5,484,444

Briefly, and for purposes of example, a delivery device (not shown) for a self- expandable stent-graft such as 42 shown in Figures 3 and 4 can include an elongated and flexible inner tube having proximal and distal ends The stent or stent-graft 42 is positioned around the inner tube in its reduced-radius, compressed state, and constrained in the compressed state by an outer tube that surround the inner tube and the stent-graft A deployment mechanism which can be actuated from the proximal end of the delivery device retracts the outer tube with respect to the inner tube, thereby allowing the stent-graft 42 to self-expand The assembled delivery device is inserted percutaneously into the femoral artery and directed through the artery until the distal end with the constrained stent-graft 42 is positioned at the diseased vessel portion 26 The deployment mechanism is then actuated to allow the stent-graft 42 to self-expand into engagement with the aorta 12 In the examples shown in Figures 3 and 4, both ends of the stent-graft 42 are positioned to engage the relatively healthy vessel „„ ,„ „, O 99/34748

portions 27 and 28 In other embodiments (not shown), only one end of the stent-graft 42 is engaged with a relatively healthy portion 27 or 28 of the aorta 12

The bands described above with references to Figures 5 - 8 are formed from solid or continuous sections of porous or microporous materials The bands can also be formed from combinations of these materials Yet another embodiment of a band which can be used with the present invention, band 540, is shown in Figure 9 Band 540 is macroporous, having relatively large holes 560 through the material from which the band is formed Alternatively band 540 can be made with a combination of large holes and microporous holes

The present invention offers a number of important advantages In particular, the efficacy of stents and stent-grafts implanted in accordance with the method is improved since the possibility of dislodgment and migration is reduced The device can also be relatively easily implanted using minimally invasive surgical techniques The overall efficiency and effectiveness of health care delivery services is thereby enhanced

Although the present invention has been described with reference preferred embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention In particular, although described in connection with an aortic aneurysm, the device can be used in connection with stents, stent-grafts and similar devices implanted throughout the vasculature and other tubular structures of a patient

Claims

WHAT IS CLAIMED IS:

1 A device for treating a section of a patient's tubular body structure having first and second adjacent portions, the device including a first band secured around an outer circumference of the second body structure portion at a location adjacent to the first body structure portion to prevent dilation of the second body structure portion

2 The device of claim 1, wherein the device has first and second opposite ends which are fixedly engaged with one another

3 The device of claim 2 and further including a tubular support structure in the patient's body structure, the tubular support structure extending through at least a portion of the first body structure portion, and engaging an inner circumference of the second body structure portion at a location adjacent to the first body structure portion, to prevent movement of the tubular support structure by the band

4 The device of claim 3 wherein the tubular support structure is a radially expandable structure

5 The device of claim 1 for treating a section of the patient's body structure also having a third portion adjacent to the first portion and opposite the first portion from the second portion, wherein the device further includes a second band secured around an outer circumference of the third body structure portion at a location adjacent to the first body structure portion to prevent dilation of the third body structure portion

6 The device of claim 5 and further including a tubular support structure in the patient's body structure, the tubular support structure extending through the first body structure portion and engaging an inner circumference of the second and third body structure portions, to prevent movement of the tubular support structure by the first and second bands

7 A device for treating a patient's vessel having a first weakened vessel portion adjacent to and between second and third relatively healthy vessel portions, including a radially expandable stent or stent graft in its expanded state extending through at least a portion of the weakened vessel portion and engaging an inner circumference of the second healthy vessel portion, and a first band wrapped around an outer circumference of the second healthy vessel portion to prevent dilation of the second healthy vessel portion and movement of the stent or stent-graft

8 The device of claim 7 wherein the stent or stent-graft m its expanded state extends through the weakened vessel portion and engages an inner circumference of the third healthy vessel portion, and a second band wrapped around an outer circumference of the third healthy vessel portion to prevent dilation of the third healthy vessel portion and movement of the stent or stent-graft

9 The device of claim 8 wherein the first and second bands each include a pair of fixedly engaged opposite ends

10 The device of claim 7 wherein the first band includes a pair of fixedly engaged opposite ends

1 1 A method for treating a section of a patient's tubular body structure having first and second adjacent portions, including securing a band around an outer circumference of the second body structure portion at a location adjacent to the first body structure portion to prevent dilation of the second body structure portion

12 The method of claim 1 1 wherein securing the band around the second body structure portion includes providing a band having first and second opposite ends, wrapping and tightening the band around the circumference of the second body structure portion, and fixedly engaging the first and second ends of the band to one another

13 The method of claim 12 and further including implanting a tubular support structure in the section of the patient's body structure, the support structure extending through at least a portion of the first body structure portion, engaging an inner circumference of the second body structure portion at a location adjacent to the first body structure portion, and being prevented from moving by the band

14 The method of claim 13 wherein implanting the support structure in the section of the patient's body structure includes providing a support structure which is radially expandable from a reduced- diameter compressed state to an enlarged-diameter expanded state, delivering the device to the section of the patient's body structure in the compressed state, and causing the support structure to expand to the expanded state and to engage the inner circumference of at least the second body structure portion

15 A method for treating an aortic aneurysm having a dilated vessel portion adjacent to at least one relatively healthy neck portion, including implanting a stent or stent-graft in the aneurysm, the stent or stent-graft engaging the inner circumference of at least the one neck portion and extending into the dilated vessel portion, wrapping and tightening a band having first and second opposite ends around the outer circumference of at least the one neck portion at a location adjacent to the dilated portion before or after implanting the stent or stent-graft, and fixedly engaging the first and second ends of the band to one another to secure the band to the outer circumference of the neck portion, to prevent dilation of the neck portion and migration of the stent or stent-graft