Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent combined with surgical delivery system
Reexamination Certificate
1998-08-04
2001-10-23
Recla, Henry J. (Department: 3731)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent combined with surgical delivery system
C606S198000, C606S200000
Reexamination Certificate
active
06306163
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of surgical instruments. Specifically, the present invention relates to an emboli-capture device for treating cerebral blood vessels such as carotid arteries.
Stenting and angioplasty in stenosed cerebral vessels (e.g., carotid arteries) pose risks of dislodging thrombus or friable plaque. The thrombus or plaque can become lodged in the brain or arteries and cause serious injury such as a stroke. If such embolic material is dislodged during a stenting procedure, it is necessary to collect the material before the it migrates and causes injury. A previous invention, U.S. Pat. No. 4,921,478, “Cerebral Balloon Angioplasty System,” Solano et al., employs an occlusion catheter carrying a relatively large inflatable occlusion balloon to repair vessels. The balloon is capable of being formed into a funnel while simultaneously sealing a vessel and establishing retrograde blood flow. The balloon is bulky and difficult to refold and withdraw from lesions within the vessels. The withdrawal is prone to causing extensive tissue damage and dislodging more emboli. Moreover, the balloon-type system will not work effectively without a complete and perfect seal between the balloon and the vessel wall. Moreover, Solano et al. contemplates no occlusion in conjunction with the deployment of a self-expanding stent. Furthermore, although the prior art filtered the blood, sometimes excess emboli remained when the device was removed from blood vessels.
What has been needed and heretofore unavailable is a means to deliver and implant a stent in conjunction with a safe and easy-to-use device and method of use for stenting blood vessels while minimizing the risk of embolic migration. The present invention satisfies this need.
SUMMARY OF THE INVENTION
The present invention is directed to an apparatus and method for treating stenosed cerebral blood vessels such as carotid arteries. The system generally includes an apparatus and method for safely and easily deploying a self-expanding stent in a vessel while preventing embolic migration.
In a preferred embodiment, a system for percutaneously delivering a stent within a vessel while preventing embolic migration includes: a restraining sheath that is capable of both expanding and retracting whereby minimal friction is created between the restraining sheath and the stent during deployment of the stent; a filter for trapping and retaining embolic material, the filter being located relative to the restraining sheath such that the filter will trap any embolic material flowing into the restraining sheath; a stent delivery catheter having a proximal end open to atmospheric pressure and a distal end connected to a proximal end of the restraining sheath; and a stent that initially is in a collapsed state and positioned within the restraining sheath.
The filter may consist of one of many devices already in use, e.g., a strainer device comprised of a plurality of wires. The expansion of the restraining sheath may be accomplished by mechanically pushing a composite sheath using a design similar to that of an umbrella.
In another preferred embodiment, expansion of the filter may be accomplished by using a wedge and spine mechanism to open the restraining sheath from a closed position.
In another preferred embodiment, the expansion of the filter may be accomplished by releasing a plurality of bent wires that are restrained in a straightened position.
The sheath design provides optimal deployment of the self-expanding stent because the sheath both expands in a radial direction and retracts in a proximal direction simultaneously. Therefore, due to the angle of incidence created between the sheath and the stent during deployment there is a low coefficient of friction between the sheath and the stent. This is an ideal configuration for recapturing a partially deployed stent because contact is constantly maintained between the sheath and the undeployed part of the stent.
A desired site within a vessel is first accessed with the system. The restraining sheath is then deployed while being moved proximally. The restraining sheath, as it expands, forms an occlusive conical member or catch basin at a proximal end of the stent. The stent, being self-expanding, is automatically deployed as the restraining sheath expands. A temporary seal is created between the stent and the restraining sheath. An outer edge of a distal end of the restraining sheath may include a material taken from the group of materials consisting of soft plastic, rubber, and a gel, in order to ensure a proper seal between the sheath and the stent. Therefore, unlike the situation where a balloon exerts pressure on a vessel wall to cause a seal, in the present invention vessel damage is minimized.
The filter is located within the restraining sheath at the occlusion site in another embodiment.
In yet another preferred embodiment, the filter may be located within the stent delivery catheter. Alternatively, the filter may be located outside of the patient's body.
Due to the occlusion of the vessel at the proximal end of the stent, a pressure differential is created between the more distal arteries (pressurized at blood pressure plus atmospheric pressure) and a lumen of the stent delivery catheter (pressurized at atmospheric pressure). Therefore, retrograde blood flow is induced and blood and embolic particles are flushed into the filter where the embolic particles are captured.
In another preferred embodiment, a vacuum apparatus may be included in the system if the occlusion is not adequate to induce sufficient retrograde blood flow or to ensure that the maximum number of embolic particles are aspirated into the filter. The restraining sheath is then collapsed to its original size, thereby trapping any remaining embolic material. The system is then removed from the patient.
Other features and advantages of the present invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying exemplary drawings.
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Advanced Cardiovascular Systems Inc.
Fulwider Patton Lee & Utecht LLP
Lewis William
Recla Henry J.
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