Patent Application
20100249898
The present invention relates generally to the field of implantable medical devices. More particularly, the invention relates to an endoluminal prosthetic assembly and method with enhanced perfusion.
Aortic aneurysms are bulges or sacs that form in the aorta resulting from the vessel wall losing its elasticity. In certain cases, the force of normal blood pressure in the aneurysm may lead to the rupture of the vessel. Aneurysms are most commonly the result of fatty deposits on the vessel wall but may also result from other causes that weaken the vessel wall, including heredity, trauma, and disease. Abdominal aortic aneurysms (AAA) form in the portion of the aorta that extends through the abdomen and thoracic aortic aneurysms (TAA) form in the portion of the aorta located within the thoracic cavity.
A number of methods and devices for treating aneurysms in the aorta, either AAA or TAA have been developed. A historically standard treatment is conventional open surgery, which is performed to replace the section of the vessel where the aneurysm has formed. The aneurysm is accessed by a surgeon through an incision in the abdomen. The portion of the blood vessel where the aneurysm has formed is shut off from the main portion of the blood vessel and then replaced with a synthetic graft. Surgery is performed under general anesthesia and takes three to four hours to complete. Following the surgery, the patient may spend time in an intensive care unit and may remain in the hospital for several days.
For several reasons, including current physical condition of the patient, some patients are not good candidates for such open surgery. Due to the highly invasive nature of the open procedure, some patients may not wish to undergo the treatment. These patients have to live with the continued risk of aneurysm rupture. Thus, alternative methods of treating an AAA or TAA are desirable.
One alternative treatment is a technique known as endovascular stent grafting. In this procedure, a stent graft is placed inside the vessel affected by the aneurysm in order to reinforce the weakened vessel wall, thereby reducing strain on the vessel wall to reduce the chance of rupture of the aneurysm. The stent graft is guided to the area of the aneurysm using a delivery catheter, typically via the femoral artery and the iliac artery into the aorta. A sheath on the catheter is retracted or released allowing the self-expanding stent graft to expand and be deployed and fixed into position.
Stent grafts for use in abdominal aortic aneurysms typically include a support structure supporting woven or interlocked graft material. Examples of woven graft materials are woven polymer materials, e.g., Dacron® material. Interlocked graft materials include knit, stretch, and velour materials. Expanded polytetrafluoroethylene (ePTFE) is also sometimes used. The graft material is secured to the inner or outer diameter of the support structure, which supports the graft material and/or holds it in place against a vessel wall. The stent graft is secured to a vessel wall above and below the aneurysm. A proximal spring stent of the stent graft can be located above the aneurysm to provide a radial force to engage the vessel wall and seal the stent graft to the vessel wall. In other examples, a stent graft anchor is utilized to affix the stent graft to the wall of a vessel.
In the event of an aneurysm that is near or contains an ostium of a branch vessel, stent grafts can be difficult to place while preserving appropriate perfusion through the branch vessel. For example, for a AAA aneurysm near or involving the ostia of the renal arteries, it is desirable to treat the aneurysm while maintaining perfusion of the kidneys. Prior art solutions have included bifurcated stent grafts and aorto-uni-iliac (“AUI”) designs. However, these designs are less than optimal for some applications. Additionally, it would be desirable to have a stent graft system that is easy to place.
It would be desirable to overcome the above disadvantages.
One aspect according to the present invention provides a stent graft system includes a first stent graft having a first end and a second end opposing the first end. The system further includes a second stent graft in fluid communication with the first stent graft. The second stent graft defines a lumen and includes a third end in fluid communication with the second end and a fourth end opposing the third end. The system further includes at least a first sleeve extending radially therefrom and in fluid communication with the lumen, and a third stent graft in fluid communication with the second stent graft, the third stent graft including a fifth end in fluid communication with the fourth end. The first sleeve includes a flexible material configured to evert between a first position such that the first sleeve is positioned within the lumen and a second position such that the first sleeve is positioned exterior to the lumen.
The foregoing and other features and advantages will become further apparent from the following detailed description, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative.
Embodiments according to the invention will now be described by reference to the figures wherein like numbers refer to like structures. The terms “distal” and “proximal” are used herein with reference to the direction of blood flow from the heart in using the stent graft system in the vasculature: “distal” indicates an apparatus portion distant from, or a direction away from the heart and “proximal” indicates an apparatus portion near to, or a direction closest to the heart.
Second stent graft 120 includes at least a first sleeve 150 extending radially therefrom. The second stent graft 120 includes a main graft section 155, and the main graft section 155 is in fluid communication with the first sleeve 150.
First stent graft 110 includes a first end 106 and second end 107. Second stent graft 120 includes a third end 108 and fourth end 109. Third stent graft includes at least a fifth end 111. Second end 107 and third end 108 are in fluid communication and affixed when deployed. Fourth end 109 and fifth end 111 are in fluid communication and affixed to each other when deployed. In one embodiment, when deployed, the third end 108 is positioned within a lumen defined by the second end 107 and fixed thereto by an interference fit between the pieces, and the fifth end 111 is positioned within the lumen defined by the fourth end 109 and fixed thereto by an interference fit between the pieces. In another embodiment, when deployed, the fourth end 109 is positioned within the lumen defined by the fifth end 111 and the second end 107 in positioned within the lumen defined by the third end 108. The first stent graft 110 and second stent graft 120, as well as the second stent graft 120 and third stent graft 130, can be affixed to each other to maintain their relative positions using appropriate techniques, such as interfering expandable rings, stent graft anchors, or physical contact between stent frameworks of the associated stent grafts.
Each of first stent graft 110, second stent graft 120, and third stent graft 130 includes a support structure, such as a stent framework, as well as a woven graft material supported by the support structure. The support structure is optimally manufactured from a biocompatible material, such as stainless steel, nitinol, tantalum, ceramic, nickel, titanium, aluminum, polymeric materials, MP35N, stainless steel, titanium ASTM F63-83 Grade 1, niobium, high carat gold K 19-22, combinations of the above, and the like. Positioning of the stent grafts discussed herein may be improved by ensuring that the support structure is fluoroscopically opaque. The cross-sectional shape of the finished support structures may be circular, ellipsoidal, rectangular, hexagonal, square, or other polygon, depending on the size and shape of the vessel across which the system is implanted. The woven graft material can include one or more suitable implantable materials having good tensile strength, such as a material suitable for resisting expansion when the force associated with blood pressure is applied to its tubular configuration after completion of the stent grafting procedure. The graft material may be a suitable biocompatible plastic, such as implantable quality woven polyester. In some embodiments, graft material includes components made of collagen, albumin, an absorbable polymer, or biocompatible fiber. Alternatively, graft material is one or more suitable metallic, plastic, or non-biodegradable materials. In certain embodiments, the sleeve 150 may be coated with a lubricious coating, such as a biocompatible coating. For example, the sleeve 150 may be coated with a silicone lubricious coating to ease in eversion and deployment from within the second stent graft 120 to the exterior of the second stent graft. Other coatings, such as polytetrafluroethylene (PTFE), or a hydrophilic coating are also envisioned.
In one embodiment, the support structure of the second stent graft 120 has a stent pattern on the graft material that is interrupted in the graft section near the ostium for the sleeve 150 or the artery so as to reduce inducing turbulence in the blood flow. In other embodiments, the support structure in the second stent graft 120 extends along the length and circumference of the second stent graft without interruption. Alternatively, second stent graft 120 can include two support structures, with a first support structure located near the third end, and the second support structure located near the fourth end such that the first support structure is offset from the second support structure and the first support structure does not contact the second support structure.
In one embodiment, the system further includes at least a first plunger sized to extend the first sleeve from inside main graft section 155 to the exterior of the main graft section. In such embodiments, the second stent graft is deployed at the desired location and the plunger 168 is threaded through the first stent graft and into the second stent graft to make contact with the first sleeve and push the first sleeve out of the lumen.
Specifically, in
In another embodiment, the sleeve 150 further includes a loop at a distal end (distal as determined after deployment), and the system includes a hook sized to catch the loop and pull the sleeve 150 from inside the main graft section 155 to outside the main graft section. In such an embodiment, multiple entrances into the vascular system may be required so that the second stent graft can be delivered to the primary vessel via a first approach, while the hook can be delivered into the side vessel to access the sleeve 150 while within the primary vessel and pull the sleeve 150 into the side vessel. Such an embodiment is illustrated, e.g. in
In one embodiment, the first stent graft, second stent graft, and third stent graft are integral with each other. In other embodiments, a two-part system combining either the first stent graft and second stent graft, or the second stent graft and third stent graft, may be utilized. In the modular approach outlined, the need for customized lengths and diameters is reduced as the sizing can be, at least partially, accomplished in the patient. However, it is contemplated that integral stent grafts including a sleeved portion in the middle and a bifurcated distal end may be created.
As also shown in
Additionally, in certain embodiments of the invention, a therapeutic drug coating may be applied to at least one of the stent graft material and support structure. This therapeutic drug coating can be configured to elute to obtain certain therapeutic goals. Appropriate methods of applying the therapeutic agent include, but are not limited to, dipping, spraying, pad printing, inkjet printing, rolling, painting, micro-spraying, wiping, electrostatic deposition, vapor deposition, epitaxial growth, and combinations thereof. As just one example, the therapeutic agent may be contained in a gel that is sprayed onto the outer surface of the stent framework and the graft member. Exemplary therapeutic drugs include, but are not limited to anti-restenotic drugs, anti-inflammatories, or the like.
Those of skill in the art will recognize that the techniques and structures disclosed herein allow for even a very large aneurysm located near the ostium of a side vessel can be effectively sealed off while maintaining appropriate perfusion through the side vessel as well as downstream from the aneurysm.
While specific embodiments according to the invention are disclosed herein, various changes and modifications can be made without departing from the spirit and scope of the invention.
