Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-08-30
2002-02-05
Mendez, Manuel (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S509000, C606S194000
Reexamination Certificate
active
06344028
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to stents positionable within the body of a patient and more particularly relates to a stent for delivering a therapeutic agent therefrom and a method and system for delivery of a therapeutic agent to replenish the stent.
2. Description of Related Art
Physicians often use medical guidewires and catheters in combination. Medical guidewires are devices navigable through narrow passages in the body such as vessels, tubes, ducts, passages and the like, hereinafter collectively referred to as vessels. A physician controls the position and travel of a mechanism at a proximal end outside the body. In other applications the physician guides the catheter through a laparoscope or endoscope. Medical catheters generally comprise hollow, flexible tubes that convey fluids, such as contrast, embolic, or pharmacological agents, to or from a vessel within a body.
Typically in transluminal procedures, a physician inserts and directs a medical guidewire through a vessel in a patient's body. The physician monitors the travel of the guidewire by a fluoroscope or other known device. Once positioned proximate the desired area, a steering mechanism is removed from the guidewire and a medical catheter is inserted into the vessel along the guidewire. Other procedures are also well known for directing catheters or similar devices into larger vessels of the body such as the esophagus.
Often these catheters include specialized attachments for providing different treatment modalities. For example, the following references disclose catheters with attachments for administering a therapeutic agent and performing balloon therapy:
4,824,436
(1989)
Wolinsky
4,832,688
(1989)
Sagae et al.
5,254,089
(1993)
Wang
08/105,737
(1993)
Lennox et al.
U.S. Pat. No. 4,824,436 to Wolinsky discloses a multi-lumen catheter having opposed ring balloons positionable on opposite sides of a plaque formation in a blood vessel. Inflation of the ring balloons define an isolated volume in the vessel about the plaque. Heparin is then injected into the volume between the ring to assist the body in repairing the plaque deposit. This patent also discloses a central balloon which can be employed to rupture the plaque prior to inflation of the ring balloon.
U.S. Pat. No. 4,832,688 to Sagae et al. discloses a multi-lumen catheter having an occlusion balloon positionable distally of a tear in a vessel wall. Inflating the balloon occludes the vessel and isolates at the tear. A therapeutic agent, such as heparin or thrombin, injected from the catheter into the volume reduces the risk of thrombosis or restenosis. The balloon is then deflated and moved adjacent the rupture and reinflated to repair the ruptured wall by coagulation of blood thereat.
U.S. Pat. No. 5,254,089 discloses a balloon catheter having an array of conduits disposed within the outer wall of the balloon. The conduits include apertures in the other wall for delivery of medications through the wall of the balloon into the body of a patient. This type of balloon is often referred to as a channeled balloon.
U.S. application Ser. No. 08/105,737 to Lennox et al., discloses catheters having spaced balloons for treating aneurysms. The inflated balloons define an isolated volume about the aneurysm. A port connects a vacuum source to evacuate the volume and draw the aneurysmal wall toward its ordinary position. Inflating a third balloon with a heated fluid to contact the aneurysmal wall effects the repair.
Therapeutic agent and balloon delivery systems must meet certain criteria. That is, the cross-sectional dimension of the catheter must be minimized to enable transit through the vessel while also having sufficient dimension to enable fluid flow to selectively inflate and deflate the balloon, guidewires to pass therein, and therapeutic agents to flow therethrough for delivery along the catheter. Catheters must also have sufficient internal rigidity to prevent collapse of the lumens while having sufficient flexibility for passage along vessels.
The following references disclose stent delivery systems:
4,690,684
(1987)
McGreevy et al.
4,922,905
(1990)
Strecker
4,950,227
(1990)
Savin et al.
5,059,211
(1991)
Stack et al.
5,108,416
(1992)
Ryan et al.
5,158,548
(1992)
Lau et al.
5,234,457
(1993)
Anderson
5,242,399
(1993)
Lau et al.
Stent delivery systems, as disclosed by the Lau et al. and Ryan et al. patents, often include a catheter supporting a compacted stent for transport in a vessel and an expansible device for expanding the stent radially to implant the stent in the vessel wall. After removal of the catheter, the expanded stent keeps the vessels from closing.
The McGreevy et al. patent discloses a stent formed of biologically compatible material, such a frozen blood plasma or the like. According to McGreevy et al., a stent of this type carried by a catheter may be inserted into opposed ends of a ruptured vessel to support the separated vessel walls while the ends are bonded together. Once deployed, the heat from the bonding operation and the body eventually melt the stent and clear the vessel.
The Strecker, patent describes a stent and delivery system. The stent is knitted from metal or plastic filaments and has a tubular structure. The delivery system includes a balloon catheter and a coaxial sheath. The catheter supports and carries the compacted stent to a site within the body. The sheath covers the stent preventing premature deployment and facilitating transit of the stent through passages in the body. Exposure of the stent by moving the sheath axially with respect to the catheter and expansion of a balloon urges the stent into contact with the walls of the vessel. Deflation of the balloon frees it from the stent and enables withdrawal from the vessel of the delivery system.
In the Savin et al. patent a stent delivery system includes a catheter having an expansible distal portion, a stent carried thereon in a contracted position for expansion thereby and sleeves that overlie the end portions of the stent. The sleeves protect the vessel and the stent during transit without substantially inhibiting deployment of the stent.
The Stack et al. patent discloses a stent delivery system comprising a catheter for delivering a compressed stent on a balloon or mechanical extension to the locus of a stenotic lesion. The balloon or mechanical extension proximate the distal end expands the stent and deflation of the balloon or retraction of the mechanical extension permits withdrawal of the distal end of the catheter through the stent. The stent comprises bioabsorbable porous material that reduces the likelihood of embolization and promotes tissue ingrowth in order to encapsulate the stent.
In accordance with the Anderson patent a stent delivery system includes a dissolvable material that impregnates a self-expanding stent in a compacted form. In one embodiment the removal of a sheath exposes the stent to body heat and liquids so that the material dissolves and the stent expands into a
Stent delivery systems used in such procedures generally include catheters with selectively expansible devices to deliver and expand a contracted “stent” or restraints that can be removed to allow a self-expanding stent to assure an enlarged or expanded configuration. Stents are known and have a variety of forms and applications. For example, stents serve as prostheses and graft carriers in percutaneous angioplasty. Stents used as an endoprothesis and graft carriers to which the present invention relates usually comprise radially expansible tubular structures for implant into the tissue surrounding “vessels” to maintain their patency. As is known, such stents are utilized in body canals, blood vessels, ducts and other body passages, and the term “vessel” is meant to include all such passages.
Like the previously described therapeutic agent and balloon therapy systems, stent delivery systems must conform to several important criteria. First, it is important to minimize the transverse dimension of the
Boston Scientific Corporation
Mendez Manuel
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