Patent Application
20170056151
The present embodiments relate generally to medical devices, and more particularly, to endografts used to treat a diseased vessel or region of vessels.
The functional vessels of human and animal bodies, such as blood vessels and ducts, occasionally weaken or even rupture. For example, the aortic wall can weaken, resulting in an aneurysm. Upon further exposure to hemodynamic forces, such an aneurysm can rupture. One study found that in Western European and Australian men who are between 60 and 75 years of age, aortic aneurysms greater than 29 mm in diameter are found in 6.9% of the population, and those greater than 40 rpm are present in 1.8% of the population.
One surgical intervention for weakened, aneurysmal, or ruptured vessels is EndoVascular Aneurysm Repair (EVAR) which involves accessing the diseased vasculature through peripheral vessels (e.g., iliac arteries) and deploying an endoluminal prosthesis such as a stent-graft or endograft. EVAR is less invasive than an open surgical repair, which involves opening the thorax and/or abdomen to sew in a replacement vessel analog (e.g., unsupported Dacron tube). In EVAR, the prosthesis may provide some or all of the functionality of the original, healthy vessel and/or preserve any remaining vascular integrity by replacing a length of the existing vessel wall that spans the site of vessel failure. A properly placed prosthesis excludes the diseased and/or aneurysmal portion of the vessel. For weakened or aneurysmal vessels, even a small leak (“endoleak”) in or around the prosthesis may lead to the pressurization of the treated vessel which may aggravate the condition that the prosthesis was intended to treat. A prosthesis of this type can treat, for example, aneurysms of the abdominal aortic artery.
In general, delivery and deployment devices for endoluminal prostheses may include devices for retaining and releasing the prosthesis into the body lumen. For example, such a device may include a sheath for radially retaining the prosthesis in a compressed configuration. A pusher may be provided for pushing the sheath and the prosthesis into the body lumen and for delivering the device into a desired position. To deploy the prosthesis, the sheath may be withdrawn over the pusher and the prosthesis, thereby causing the prosthesis to become exposed and to expand into the body lumen.
The present embodiments describe an endograft having one or more apertures, and methods for constructing the same. In one embodiment, the endograft may comprise two apertures separated by a partition. Optionally, the apertures may be oriented at an oblique angle relative to a central longitudinal axis. Optionally, extension limbs may extend through the apertures. The endograft may include one or more fenestrations and/or an attachment stent to facilitate blood flow to specific anatomy.
In another example, the endograft may have at least one contralateral limb and at least one aperture The aperture may be oriented at an oblique angle relative to a central longitudinal axis. Additionally, the aperture may be open or closed. In a related example, the endograft may comprise an extension limb extending through an open aperture.
In another example, the endografts may be constructed using a modular approach, with a main body and a tubular extension body, where the extension body may have one or more fenestrations.
Other systems, methods, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be within the scope of the invention, and be encompassed by the following claims.
The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.
In the present application, the term “proximal” refers to a direction that is generally closest to the heart during a medical procedure, while the term “distal” refers to a direction that is furthest from the heart during a medical procedure.
The embodiments described below are in connection with systems and methods for the introduction and deployment of an implantable medical device in a vessel, such as endovascular prostheses, but could also be used for deploying a range of implantable medical devices including, but not limited to, stents, occlusion devices and the like.
Referring to
Endografts may be implanted in the aorta 10, such that blood flowing past the aneurysm 20 flows through the endograft. Use of an endograft reduces pressure on the aneurysm 20 and can cause the aneurysm 20 to shrink in size. Endografts may incorporate self-expanding, stents. The final shape, size, and position of the endograft in situ may also be modified through use of a balloon (e.g., CODA balloon catherer).
Endografts may be implanted in other arteries (not shown). For example, the renal arteries are not often aneurysmal, but may nonetheless be treated with covered stents in cases where there is insufficient healthy vessel length to use for sealing. In the case of a juxtarenal or thoraco-abdominal aortic aneurysm (TAAA), the aneurysm encompasses the ostia. To maintain a sealing zone, a minimal length (e.g., 4 mm) of native healthy vessel tissue is required below the renal arteries when placing a graft that will not include fenestrations or other accommodations.
The support structure 110 of the endograft 100 may have any suitable stent pattern known in the art. The support structure 110 may be self-expanding or may expand under external pressures, for example from an inflatable balloon at the tip of a balloon catheter. One example of a stent pattern is the Z-stent or Gianturco stent design. Each Z-stent may include a series of substantially straight segments or struts interconnected by a series of bent segments or bends. The bent segments may include acute bends or apices. The Z-stents are arranged in a zigzag configuration in which the straight segments are set at angles relative to one another and are connected by the bent segments. Alternative stents may include, for example, annular or helical stents. The gents mentioned herein may be made from standard medical grade stainless steel. Other gents may be made from nitinol or other shape-memory materials.
Further, as shown in
The graft material 120 may be coupled to the external Z-stents 110a and internal Z-stents 110b by known methods, for example biocompatible stitching 200. The graft material 120 may be fabricated from any at least substantially biocompatible material including such materials as polyester fabrics, polytetrafluoroethylene (PTFE), expanded PTFE, and other synthetic materials known to those of skill in the art. In some embodiments in accordance with the technology, the graft material 120 may also include drug-eluting coatings or implants.
When deploying the endograft 100 into the lower aorta 10 in the region of aortic bifurcation 60 (or existing implant bifurcation (not shown) or new implant bifurcation (not shown)), it may be desirable to provide at least one fenestration 170 in the main body 140 to avoid occluding the renal arteries 30 or the superior mesenteric artery. In the embodiment of
The distal region 150 may have one or more apertures 180 that are substantially round or circular. The apertures 180 may be separated by a partition 240. The partition 240 may be formed by connecting portions of the distal region 150 via biocompatible stitching 200 or tailoring (not shown). The distal regions 150 and/or partition 240 may be contiguous with the graft material 120 of main body 140. Alternatively, the distal region 150, including the partition 240, may be formed from one piece that is connected to the main body 140, for example, via biocompatible stitching 200 or tailoring (not shown). Other manufacturing techniques can also be employed.
In certain embodiments (such as shown), the apertures 180 may have an oblique orientation relative to a central axis 230. The angle of the apertures 180 can be measured by measuring the angle between a normal vector to the plane of the aperture 180 and the central axis 230 of the endograft 100. For example, in the embodiment of
In the current, non-limiting example, the graft material 120 of the main body 140 may be disposed within the abdominal aorta 10 above an aortic bifurcation 60, such that the attachment stent 190 may span the renal arteries 30, whereby blood may flow through the struts of the attachment stent 190 and into the renal arteries 30. In such an embodiment, the fenestrations 170 may be replaced with closed fenestrations 170′ (such as shown) or absent (not shown) to prevent fluid communication outside the endograft and to prevent endoleak. Alternatively, by varying the length of the main body 140, the fenestrations 170 may align with the renal arteries 30, as described above with respect to the embodiments shown in
The distal region 150′ may transition into one or more contiguous limbs, for example, contralateral limb 300. The contralateral limb 300 may comprise proximal end 310, distal end 320, and a lumen 330 extending therebetween. The lumen 330 of the contralateral limb 300 may be in fluid communication with the lumen 160′ of the endograft 100′.
The support structure 110′ of the endograft 100′ may have any suitable stent pattern known in the art. In the current, non-limiting example, the support structures 110′ include external Z-stents 110a′ on the proximal region 130′ and internal Z-stents 110b′ on the contralateral limb 300. The contralateral limb 300 may have multiple support structures 110′ along the length from the proximal end 310 to the distal end 320. Given varying design configurations, some external Z-stents 110a′ may be replaced with internal Z-stents 110b′, and vice versa, or other support structures 110′ known in the art.
The contralateral leg 300 may be made from a graft material 120′ connected to the external Z-stents 110a′ and internal Z-stents 110b′ by known methods, for example biocompatible stitching or tailoring. The graft material 120′ may be made from a substantially impermeable, biocompatible, and flexible material, as described above.
The aperture 180′ may be either open or closed. In an open configuration, blood may flow bilaterally through both the contralateral limb 300 and the aperture 180′, as shown in
The extension limb 400 may have multiple support structures 110′ along the length from the proximal end 410 to the distal end 420, for example external Z-stents 110a′. Given varying design configurations, some external Z-stents 110a′ may be replaced with internal Z-stents 110b′, and vice versa.
The extension limb 400 may be made from a graft material 120′ connected to the external Z-stents 110a′ and internal Z-stents 110b′ by known methods, for example biocompatible stitching. The graft material 120′ may be made from a substantially impermeable, biocompatible, and flexible material, as described above.
The proximal end 410 of extension limb 400 may sealingly engage with an aperture 180′ of the endograft 100′. The seal may be formed via a compression fit, wherein the inner diameter of the aperture 180′ is less than the outer diameter of the proximal end 410 of the extension limb 400. Additionally, the outer diameter of the distal end 420 of the extension limb 400 may be less than, equal to, or greater than the inner diameter of the aperture 180′. The distal end 420 of extension limb 400 may be compressed or otherwise configured to extend through the aperture 180′ during implantation. The distal end 420 of extension limb 400 may sealingly engage with an inner surface of the surrounding blood vessel.
Additionally, the proximal end 410 of extension limb 400 may sealingly engage the endograft 100′ proximal to the aperture 180′, for example at the lumen 160′ of the main body 140′, and/or to the native vessel. For example, a bare attachment stent (not shown) may be connected proximal to the proximal end 410 of the extension limb 400 and deployed to extend into the lumen 160′ proximal to the aperture 180′. The bare attachment stent may circumferentially engage the graft material 120′ of the lumen 160′ to secure the position of the leg without interrupting bilateral flow (since flow would be maintained through the wires of the bare attachment stent). A seal stent may also be used to maintain an adequate seal with the endograft 100′ without interrupting flow.
In another example, the attachment stent may instead be covered either partially or entirely with a graft material. In one example, the attachment stent may be covered with a graft material to engage the lumen 160′ of main body 140′, wherein the graft material may also have an aperture (not shown) to provide fluid communication with the lumen 330 of contralateral leg 300. Some bare wire(s) of the attachment stent may span portions of the aperture, and may be sewn into a fixed position or allowed to open freely through the aperture. Alternatively, portions of the bare attachment stent may be removed, for example, portions of the stent structure spanning the aperture.
In another embodiment (not shown), multiple extension limbs 400 may sealingly engage with multiple apertures 180 or apertures 180′. For example, the embodiments of
The embodiments described herein provide two non-limiting examples of endografts that are suitable for treating an array of medical conditions, and may be especially suited for treating an abdominal aortic aneurysm 20 at or slightly above the aortic bifurcation 60. Alternatively, the bifurcation may within an existing endograft, for example one that was newly or previously implanted. As will be appreciated, the main body 140 (or 140′) may be positioned in the abdominal aorta 10 slightly above the aortic bifurcation 60, while the ipsilateral extension limb 400 may extend into one external iliac artery 40 and the contralateral limb 300 may extend into, or be positioned slightly above, the opposing external iliac artery 40, depending on length. These embodiments (and related embodiments) may be beneficial where the length between the visceral vessels (e.g., renal arteries) and the bifurcation may be extremely short, making it difficult to implant endografts with longer body lengths while maintaining access to the visceral vessels and simultaneously engaging healthy vessel walls.
Various additional modular components may be provided for the endograft 100 (or 100′), for example, additional extension limbs may be configured to overlap with the distal end 320 of the contralateral limb 300. Such an extension limb would have a proximal end that sealingly overlaps with the contralateral limb 300, and a distal end that sealingly engages an inner surface of the external iliac artery 40.
In another modular design, embodiments of endograft 100′ (or 100) may be constructed using a multi-piece construction to form a longer main body. As shown in
The proximal region 530 may include a proximal opening 610 and the distal region 550 may include a distal opening 620. In the attached configuration, the lumen 560 of the tubular main body extension 500 may be in fluid communication with the proximal opening 610, the distal opening 620, the main body lumen 160′ (or 160), the contralateral limb lumen 330, and any extension limb lumen (not shown).
Although
The modular design illustrated in
Another benefit to the modular design is customization, both for clock position (rotational orientation about the central longitudinal axis) as well as length. This is advantageous because the manufacture of custom grafts (common for patients requiring fenestrations) may take a long time, delaying procedures that may be better performed as soon as possible. It also allows the physician to evaluate and customize on-the-fly during a procedure, by using different off-the-shelf components as the procedure advances in the operating room. The time between pre-operation imaging/scans and the procedure itself, as well as changes due to the influence of components placed, contribute to the need to be flexible intra-procedurally. Customization may be possible even where the fenestrations are included in the same piece as the apertures, since the physician could use extension limbs to curve around to openings in a bifurcation (e.g., aortic bifurcation or graft bifurcation). Furthermore, with multiple pieces where the fenestrations and apertures are initially in separate components customization is even easier and more customization options are available (e.g., clock position, body length).
While references to treatment of an aneurysm 20 at or near the aortic bifurcation 60 may be explained as one example, it will be appreciated that endografts 100 and 100′ can be positioned at other bodily locations to treat aneurysms 20 or other conditions, using the system and methods described herein.
One additional use of the embodiments described herein is for use as a secondary repair device. A patient may have a primary device previously implanted to treat an aneurysm or other condition. Over time, the effectiveness of the primary device may decrease, for example due to technical overreach, device failure, endoleaks, or disease progression. However, moving and replacing such a primary device may involve a high risk procedure. This is especially relevant as patients live longer (and live longer with endografts). As patient populations age, they tend to present with more and more challenges to open surgical procedures (co-morbidities, changes in anatomy, etc.). The only way of moving an existing device is (generally) through open repair, and many such patients may be poor candidates for open surgery. A repair option that accounts for repairs over time and that is compatible with existing implants may be a viable alternative.
The embodiments described herein may be advantageously used to repair such primary devices. The expandable support structure 110 (or 110′) may fit inside primary devices of many sizes, making it nearly “universal.” To augment or repair anatomy proximal to the primary graft and near a crucial juncture such as the renal arteries 30, the embodiments of
While various embodiments of the invention have been described, the invention is not to be restricted except in light of the attached claims and their equivalents. Moreover, the advantages described herein are not necessarily the only advantages of the invention and it is not necessarily expected that every embodiment of the invention will achieve all of the advantages described.
