Filter flush system and methods of use

Details Filter flush system and methods of use Filter flush system and methods of use

2000-09-29

2003-09-16

Casler, Brian L. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C606S200000

Reexamination Certificate

active

06620148

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to devices and methods useful in capturing embolic material in blood vessels. More specifically, the devices and methods provide a vessel filtering system for temporary deployment in arteries such as the carotid arteries and the aorta, and veins such as the subclavian vein and the superior vena cava. The system also includes a guidewire for directing endovascular devices, e.g., atherectomy, stent-deployment, or angioplasty catheters, to a region of interest and a guiding catheter with fluid flushing capability to assist in filtering.
BACKGROUND OF THE INVENTION
Treatment of thrombotic or atherosclerotic lesions in blood vessels using the endovascular approach has recently been 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 the 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, occlusion 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): 430-5 (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 procedure is associated with more than eight times the rate of microemboli seen using carotid endarterectomy. See Jordan, Jr. et al. Cardiovascular surgery 7(1): 33-8 (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. The vast majority of these devices are designed for permanent placement in veins to prevent pulmonary embolism. A temporary venous filter device is disclosed in Bajaj, U.S. Pat. No. 5,053,008 (this and all other references cited herein are expressly incorporated by reference as if fully set forth in their entirety herein). The Bajaj device is an intracardiac catheter for temporary placement in the pulmonary trunk of a patient predisposed to pulmonary embolism due to, e.g., hip surgery, major trauma, major abdominal or pelvic surgery, or immobilization. The Bajaj device includes an umbrella made from meshwork which traps venous emboli before they reach the lungs. This device is designed for venous filtration and is not suitable for arterial use because of the hemodynamic differences between arteries and veins.
There are very few intravascular devices designed for arterial use. Arteries are much more flexible and elastic than veins and, in the arteries, blood flow is pulsatile with large pressure variations between systolic and diastolic flow. These pressure variations cause the artery walls to expand and contract. Blood flow rates in the arteries vary from about 1 to about 5 L/min. 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.
Filters mounted to the distal end of guidewires have been proposed for intravascular blood filtration. A majority of these devices includes a filter which is attached to a guidewire and is mechanically actuated via struts or a pre-shaped basket which deploy 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 on the 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. A major disadvantage associated with these filter devices is that the filters generally rely on vascular blood flow to push debris into the filters. If blood flow in the vessel becomes restricted, the loosely attached embolic material may not be subjected to normal turbulent blood flow. The embolic particles may stay in the vessel proximal to the filter until the higher normal flow is re-established (i.e., when the filter is removed), thereby reducing the efficacy of the filtering devices.
Another means of removing embolic material utilizes temporary occlusion devices, such as balloon occlusion catheters and vascular clamps, to isolate a section of a vessel. After blood flow is isolated in the vessel, fluid or blood within the vessel is aspirated to remove embolic debris. One of the disadvantages associated with occlusion devices is that they require temporary cessation or reduction in distal perfusion that may affect oxygenation of distal organs. Shunts may be placed distal to the devices to maintain perfusion to distal organs. However, insertion of the shunts creates additional trauma to the vessel and may generate additional embolic material.
What is needed are simple and safe blood filtering devices which can be temporarily placed in the arteries and veins and can be used with endovascular instruments to effectively prevent distal embolization. Existing devices are inadequate for this purpose.
SUMMARY OF THE INVENTION
Fixed or mobile plaque present in the aorta can dislodge and cause renal infarct or ischemia to other organs. The build up of plaque in the carotid arteries also poses a risk of ischemic stroke by embolization and presents an additional threat of reducing blood flow by occluding the vessel lumen. Plaque present in the iliac and femoral arteries may cause ischemia of the lower extremities, either through distal embolization of atheromatous material or through in situ stenosis of the diseased blood vessel, i.e., narrowing of lumenal diameter. Atherectomy or angioplasty with or without stent deployment in these vessels prevents the above disease from occurring, but can also create these conditions unless the device is specially designed to capture embolic material dislodged during the procedure.
The present invention provides devices and methods for temporary placement of blood filtering capabilities in an artery or vein during endovascular procedures. More specifically, the invention provides a filter flush

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