Surgery – Instruments – Means for inserting or removing conduit within body
Reexamination Certificate
1999-01-06
2001-03-20
Smith, Jeffrey A. (Department: 3732)
Surgery
Instruments
Means for inserting or removing conduit within body
Reexamination Certificate
active
06203550
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to tubular endoluminal prostheses, such as stents, stent-grafts, and the like. More particularly, the present invention provides improved delivery systems and methods for their use to accurately and safely deploy endoluminal prostheses within the lumens of the body, particularly within the vascular system for treatment of aortic aneurysms, stenoses, and the like.
Vascular aneurysms are the result of abnormal dilation of a blood vessel, usually resulting from disease and/or genetic predisposition, which can weaken the arterial wall and allow it to expand. While aneurysms can occur in any blood vessel, most occur in the aorta and peripheral arteries, with the majority of aortic aneurysms occurring in the abdominal aorta, usually beginning below the renal arteries and often extending into one or both of the iliac arteries.
Aortic aneurysms are now commonly treated in open surgical procedures where the diseased vessel segment is bypassed and repaired with an artificial vascular graft. While considered to be an effective surgical technique, particularly considering the alternative of a usual fatal ruptured abdominal aortic aneurysm, conventional vascular graft surgery suffers from a number of disadvantages. The surgical procedure is complex and requires experienced surgeons and well-equipped surgical facilities. Even with the best surgeons and equipment, however, patients being treated frequently are elderly and weakened from cardiovascular and other diseases, reducing the number of eligible patients. Even for eligible patients prior to rupture, conventional aneurysm repair has a relatively high mortality rate, usually from 2% to 10%. Morbidity related to the conventional surgery includes myocardial infarction, renal failure, impotence, paralysis, and other conditions. Additionally, even with successful surgery, recovery takes several weeks, and often requires a lengthy hospital stay.
In order to overcome some or all of these drawbacks, endovascular prosthesis placement for the treatment of aneurysms has been proposed. Although very promising, many of the proposed methods and apparatus suffer from undesirable limitations. In particular, accurate delivery and placement of the endovascular prosthesis within the vasculature can be problematic.
Stent-grafts are often resilient structures, biased to expand against the surrounding lumenal wall. Such resiliently-expanding stent-grafts are tightly compressed within the catheter, imposing significant forces against the surrounding catheter sheath. This can often lead to excess friction between the stent-graft and the sheath, particularly when the resiliently-expanding structure invaginates into the catheter material. As these catheters are often required to maneuver within the tortuous vascular system, catheter sheaths are often formed as flexible, elongate bodies which are particularly susceptible to invagination of the tightly compressed stent-graft in the flexible material of the catheter wall.
For these reasons, it would be desirable to provide improved devices, systems, and methods for endoluminal deployment of prostheses such as stents, stentgrafts, and the like, for treatment of aneurysms and other diseases of the body lumens. It would be particularly desirable if such improved systems and methods enhanced the accuracy and safety of the deployment procedure, without significantly increasing deployment time, equipment costs, or complexity of the deployment procedure.
2. Description of the Background Art
Devices for endoluminal placement of prostheses are described in U.S. Pat. Nos. 4,512,338, 4,651,738, 4,665,918, 5,458,615, 5,480,423, 5,484,418, 5,489,295, 4,990,151, 5,035,706, 5,433,723, 5.443,477, 5,282,824, 5,275,622, 5,242,399, 5,201,757, 5,190,058, 5,104,399, 5,092,877, 4,990,151, and EP Patent Publication Nos. EP 0 539 237 A1, 0518839 A2, EP 0505686 A1, and EP 0508473 A2.
SUMMARY OF THE INVENTION
The present invention provides improved systems, devices, and methods for deployment of endoluminal prostheses within the lumens of the body, and particularly for deployment of stents and stent-grafts within the vascular system. Optionally a sheath is withdrawn from over a tightly compressed prostheses using an actuation mechanism having a variable mechanical advantage, which varies with the position of the sheath. Once deployment is safely underway, and after static frictional forces have been overcome, the remainder of the deployment may proceed more rapidly, without significantly degrading overall safety or ease of use. In some embodiments, the handle for the actuation mechanism may rotate about an axis parallel to the axis of the sheath. Regardless, the deployment systems of the present invention will preferably include a “one-way” rotation mechanism, thereby avoiding any inadvertent counter-rotation of the handle causing undesirable movement of the prosthesis or delivery system. Accuracy and ease of use of the delivery system may optionally be improved by providing an outer tube around the sheath which is coupled to the prosthesis restraining member within the sheath. The outer tube may be inserted through an introducer valve, so that friction between the outer tube and introducer valve helps restrain the prosthesis at the target position as the sheath is withdrawn proximally.
In a first aspect, the present invention provides a delivery system for use with a tubular endoluminal prosthesis. The delivery system includes a sheath having a proximal end, a distal end, and a lumen, which is capable of receiving the prosthesis near the distal end. The system also includes a member, in the lumen of the sheath. The member expels the prosthesis from the lumen as the sheath moves from a first position to a second position relative to the member. The sheath is coupled to a handle using an actuation mechanism which engages the member. Also, included in the system is a unidirectional mechanism operatively associated with the actuation mechanism. The unidirectional mechanism is capable of preventing movement of the sheath toward the first position.
In yet another aspect, a prosthetic delivery system is provided for use with a radially expandable tubular endoluminal prosthesis. The delivery system includes a sheath having a proximal end, a distal end, an axis therebetween, and a lumen capable of receiving the prosthesis near the distal end. Disposed in the lumen is a member for expelling the prosthesis from the lumen as the sheath moves from a first position to a second position relative to the member. An actuation mechanism is attached to the member and has threads which have a variable thread pitch which also varies along an axis of the threads. The actuation mechanism couples the sheath to a handle, where the handle is rotatable about an axis substantially parallel to the axis of the sheath. The handle effects movement of the sheath from the first position to the second position. The system also includes a ratchet mechanism. The ratchet mechanism includes a resilient member, which has at least one pawl and a serration ring associated with the actuation mechanism. The serration ring engages the at least one pawl in a ratcheting relationship. The resilient member is operative on the at least one pawl and urges the at least one pawl in to the engagement.
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Medtronic Inc.
Robert Eduardo C.
Smith Jeffrey A.
Sterne Kessler Goldstein & Fox P.L.L.C.
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