Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
2000-11-17
2004-01-13
Truong, Kevin T. (Department: 3731)
Surgery
Instruments
Internal pressure applicator
Reexamination Certificate
active
06676683
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to devices and methods for providing temporary placement of a filter in a blood vessel. More particularly, the invention provides a filter structure that conforms to the interior vessel wall with minimum gap and can be stowed to facilitate its passage across large vascular lesions.
BACKGROUND OF THE INVENTION
Treatment of thrombotic or atherosclerotic lesions in blood vessels using an endovascular approach has recently proven to be an effective and reliable alternative to surgical intervention in selected patients. For example, directional atherectomy and percutaneous translumenal coronary angioplasty (PTCA) with or without stent deployment are useful in treating patients with coronary occlusion. Atherectomy physically removes plaque by cutting, pulverizing, or shaving in atherosclerotic arteries using a catheter-deliverable endarterectomy device. Angioplasty enlarges the lumenal diameter of a stenotic vessel by exerting mechanical force on the vascular walls. In addition to using angioplasty, stenting, and/or atherectomy on the coronary vasculature, these endovascular techniques have also proven useful in treating other vascular lesions in, for example, carotid artery stenosis, peripheral arterial occlusive disease (especially the aorta, the iliac artery, and the femoral artery), renal artery stenosis caused by atherosclerosis or fibromuscular disease, superior vena cava syndrome, and occlusive iliac vein thrombosis resistant to thrombolysis.
It is well recognized that one of the complications associated with endovascular techniques is the dislodgment of embolic materials generated during manipulation of the vessel, thereby causing occlusion of the narrower vessels downstream and ischemia or infarct of the organ which the vessel supplies. In 1995, Waksman et al. disclosed that distal embolization is common after directional atherectomy in coronary arteries and saphenous vein grafts. See Waksman et al.,
American Heart Journal
129(3):430-435 (1995), incorporated herein by reference. This study found that distal embolization occurs in 28% (31 out of 111) of the patients undergoing atherectomy. In January 1999, Jordan, Jr. et al. disclosed that treatment of carotid stenosis using percutaneous angioplasty with stenting is associated with more than eight times the rate of microemboli seen using carotid endarterectomy. See Jordan, Jr. et al.
Cardiovascular Surgery
7(1):33-38 (1999), incorporated herein by reference. Microemboli, as detected by transcranial Doppler monitoring in this study, have been shown to be a potential cause of stroke. The embolic materials include calcium, intimal debris, atheromatous plaque, thrombi, and/or air.
There are a number of devices designed to provide blood filtering for entrapment of vascular emboli. Ginsburg, U.S. Pat. No. 4,873,978, discloses an arterial filtering system, which includes a catheter with a strainer device at its distal end. This device is inserted into the vessel downstream from the treatment site and, after treatment, the strainer is collapsed around the entrapped emboli and removed from the body. The Ginsburg device could not withstand flow rates of 5 L/min. It is designed for only small arteries and therefore could not capture emboli destined for all parts of the body. Ing. Walter Hengst GmbH & Co, German Patent DE 34 17 738, also discloses another arterial filter having a folding linkage system which converts the filter from the collapsed to the expanded state.
Another method for removing embolic debris is using an endovascular aspiration catheter. The method requires placement of an occlusion device distal to the region of interest to provide protection against distal embolization while embolic debris are aspirated by the catheter. The major disadvantage associated with the aspiration catheter is that blood flow distal to the occlusion is compromised during total occlusion of the vessel, which may result in tissue ischemia or death.
Filters mounted to the distal end of guidewires have been proposed for intravascular blood filtration. A majority of these devices includes a filter that is attached to a guidewire and is mechanically actuated via struts or a pre-shaped basket that deploys in the vessel. These filters are typically mesh “parachutes” which are attached to the shaft of the wire at the distal end and to wire struts which extend outward in a radial direction at their proximal end. The radial struts open the proximal end of the filter to the wall of the vessel. Blood flowing through the vessel is forced through the mesh thereby capturing embolic material in the filter. These devices are self-directing and can be placed intravascularly. However, there are several disadvantages associated with guidewire-filtration. First, the steerability of the guidewire may be altered as compared to conventional guidewires due to the size of the filter, and the guidewire may bend, kink, and/or loop around in the vessel, making insertion of the filter through a complex vascular lesion difficult. Secondly, the current filter designs, e.g., a basket or net, often fail to conform to the internal perimeter of the vessel, and distal embolization can still occur despite the filter placement. Thirdly, as the filter is stowed, the filter material is gathered together with “bunching” of the material at the perimeter, causing uncontrolled gathering and creating relatively large and poorly defined crossing profiles. As a result, the current filter designs require large capture sheaths to deploy and stow the filter.
Moreover, there are several problems associated with the current construction of the filter material. For example, the present method for creating a mesh, weave, or membrane having a specified pore opening to trap debris relies on the thread size used in the weave. When deployed in a vessel, the weave creates flow dynamics that activate the clotting mechanism, leading to thrombi formation. The filter material is also injurious to the red blood cells as they traverse the filter, causing intravascular hemolysis.
What is needed are simple and safe blood filtering devices that conform to a patient's vessel wall to prevent distal embolization during endovascular procedures, and provide easy steerability and a uniform controlled closure profile when stowed. Existing devices are inadequate for this purpose.
SUMMARY OF THE INVENTION
The present invention provides devices and methods that protect a patient from distal embolization during cardiovascular procedures, e.g., atherectomy, angioplasty, or stent-deployment. More specifically, filter devices that require small sheaths for deployment and conform to the interior vessel wall with minimum gap are disclosed for capturing embolic material generated during a procedure in an artery or vein.
In one embodiment, the filter device comprises a catheter and an expandable filter mounted at a distal end of the catheter. The filter has a plurality of circumferentially adjacent porous segments, arranged like the petals of a flower. Each petal is constructed from a biocompatible material, such as plastic (e.g., polyester (mylar), polyethylene tetrachloride, polyethylene, or polyvinylidene fluoride (kynar)) or metal (e.g., stainless steel, nitinol, platinum alloy, or molybdenum alloy). The processing used to create pores in the petals could be either laser or chemical etching, stamping, or cutting by hand. The pores are precision machined into the filter material, thereby providing less traumatic pathways for blood flow and minimizing activation of the intravascular clotting process. Each petal is shaped generally as an equilateral triangle having two sides and a base. Each side has means, e.g., a hook, to engage the adjacent petals. The petals are arranged generally about the surface of a cone. In certain embodiments, each petal has an extension bonded to the center of the arc and extending away from the arc. Each extension is bonded to the catheter. The filter opens by expanding an open base of the cone until the means for engaging the
Edwards Lifescience Corporation
O'Melveny & Myers LLP
Truong Kevin T.
LandOfFree
Intravascular catheter filter with interlocking petal design... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Intravascular catheter filter with interlocking petal design..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Intravascular catheter filter with interlocking petal design... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3265154