Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
2001-06-26
2003-03-25
Truong, Kevin T. (Department: 3731)
Surgery
Instruments
Internal pressure applicator
Reexamination Certificate
active
06537297
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to treating plaque deposits and occlusions within major blood vessels, more particularly to an apparatus and method for preventing detachment of mobile aortic plaque within the ascending aorta, the aortic arch, or the carotid arteries, and to an apparatus and method for providing a stent and a filter in a percutaneous catheter for treating occlusions within the carotid arteries.
BACKGROUND OF THE INVENTION
Several procedures are now used to open stenosed or occluded blood vessels in a patient caused by the deposit of plaque or other material on the walls of the blood vessels. Angioplasty, for example, is a widely known procedure wherein an inflatable balloon is introduced into the occluded region. The balloon is inflated, dilating the occlusion, and thereby increasing intraluminal diameter. Plaque material may be inadvertently dislodged during angioplasty, and this material is then free to travel downstream, possibly lodging within another portion of the blood vessel or possibly reaching a vital organ, causing damage to the patient.
In another procedure, stenosis within arteries and other blood vessels is treated by permanently or temporarily introducing a stent into the stenosed region to open the lumen of the vessel. The stent typically comprises a substantially cylindrical tube or mesh sleeve made from such materials as stainless steel or nitinol. The design of the material permits the diameter of the stent to be radially expanded, while still providing sufficient rigidity such that the stent maintains its shape once it has been enlarged to a desired size.
Generally, a stent having a length longer than the target region is selected and is disposed on a catheter prior to use. The catheter typically has a flexible balloon, near its distal end, designed to inflate to a desired size when subjected to internal pressure. The stent is mounted to the catheter and compressed over the balloon, typically by hand, to assure that the stent does not move as it passes through the blood vessel to the desired location within the patient. Alternatively, self-expanding stents may also be used.
The stent is typically introduced into the desired blood vessel using known percutaneous methods. The catheter, having the stent securely crimped thereon, is directed to the region of the blood vessel being treated. The catheter is positioned such that the stent is centered across the stenosed region. The balloon is inflated, typically by introducing gas or fluid such as saline solution, through a lumen in the catheter communicating with the balloon. Balloon inflation causes the stent to expand radially, thereby engaging the stenosed material. As the stent expands, the material is forced outward, dilating the lumen of the blood vessel.
Due to substantial rigidity of the stent material, the stent retains its expanded shape, providing an open passage for blood flow. The balloon is then deflated and the catheter withdrawn.
Because the stent is often constructed from a mesh material, the stent typically compresses longitudinally as it expands radially. Stenotic material trapped between the stent and the vessel wall may extend into the openings in the mesh and may be sheared off by this longitudinal compression to create embolic debris free. When this material travels downstream, it can cause serious complications. For example loose embolic material released within the ascending aorta, the aortic arch, or the carotid arteries may travel downstream to the brain, possibly causing stroke, which can lead to permanent injuries or even death of the patient.
Thus, there is a need for an apparatus and method for delivering a stent into an arterial occlusion which substantially reduces the risk of embolic material escaping to the vessel and causing a blockage at a downstream location. There is also an apparatus and method for substantially preventing detachment of plaque deposited on the walls of the ascending aorta, the aortic arch, the descending aorta, and the carotid arteries. In addition, there is a need for an apparatus and method to substantially contain loose embolic material within the aorta and the carotid arteries during an interventional procedure, preventing it from reaching the brain.
SUMMARY OF THE INVENTION
The present invention provides an apparatus and method for preventing embolic material from escaping a site of intervention within the aorta, the carotid arteries, and other arteries generally, thereafter causing damage to vital organs, such as the brain. More particularly, the present invention involves an apparatus and method for introducing a stent into a region of a major blood vessel within the human body having plaque deposits, such as the ascending aorta, the descending aorta, aortic arch, common carotid artery, external and internal carotid arteries, brachiocephalic trunk, middle cerebral artery, anterior cerebral artery, posterior cerebral artery, vertebral artery, basilar artery, subclavian artery, brachial artery, axillary artery, iliac artery, renal artery, femoral artery, popliteal artery, celiac artery, superior mesenteric artery, inferior mesenteric artery, anterior tibial artery, and posterior tibial artery, thereby opening occlusions and/or preventing embolic material from breaking free within the blood vessel.
In a first embodiment, the invention includes a guidewire having an expandable filter attached to it, and a stent catheter. The catheter has an inflatable balloon mounted on or near its distal end, and an inflation lumen extending through the catheter between a proximal region of the catheter and the balloon. A stent is provided on the outer surface of the catheter, substantially engaging the balloon. Generally, the stent comprises an expandable substantially rigid tube, sheet, wire or spring, but preferably a cylindrical mesh sleeve. See Pahnaz, U.S. Pat. No. 4,733,665, incorporated herein by reference.
Alternatively, the stent may be a self-expanding sleeve, preferably from nitinol. In this case, the stent catheter does not require an inflatable balloon. Instead the stent is compressed over the catheter and a sheath or outer catheter is directed over the stent to hold it in the compressed condition until time of deployment.
The guidewire has a filter assembly attached at or near its distal end, which includes an expansion frame which is adapted to open from a contracted condition to an enlarged condition. Filter material, typically a fine mesh, is attached to the expansion frame to filter undesirable embolic material from blood.
The guidewire with the expansion frame in its contracted condition is provided through a sheath or cannula, or preferably is included directly in the stent catheter. The catheter typically has a second lumen extending from its proximal region to its distal end into which the guidewire is introduced. The filter assembly on the distal end of the guidewire is then available to be extended beyond the distal end of the catheter for use during stent delivery.
The device is typically used to introduce a stent into a stenosed or occluded region of a patient, preferably within the carotid arteries. The catheter is introduced percutaneously into a blood vessel and is directed through the blood vessel to the desired region. If the filter device is provided in a separate sheath, the sheath is percutaneously inserted into the blood vessel downstream of the region being treated, and is fixed in position.
The filter assembly is introduced into the blood vessel, and the expansion frame is opened to its enlarged condition, extending the filter mesh substantially across the blood vessel until the filter mesh substantially engages the walls of the vessel.
The catheter is inserted through the region being treated until the stent is centered across the plaque deposited on the walls of the blood vessel. Fluid, preferably saline solution, is introduced through the inflation lumen, inflating the balloon, and expanding the stent radially outwardly to engage the plaque. The stent pushes the plaque away from the
Jang Yue-Teh
Maahs Tracy D.
Tsugita Ross S.
Embol-X Inc.
O'Melveny & Myers LLP
Truong Kevin T.
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