Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-01-25
2003-12-16
Casler, Brian L. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S264000, C604S035000, C604S095010, C604S096010, C604S101010, C604S101030, C604S101040
Reexamination Certificate
active
06663613
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the present invention relates to devices and methods for dissolving and disrupting occlusive materials from blood vessels.
Thrombosis and atherosclerosis are common ailments which occur in humans and which result from the deposition of thrombus within the lumens of blood vessels. When hardened, such deposits are commonly referred to as plaque. Such deposits are most common in the peripheral blood vessels that feed the limbs of the human body and the coronary arteries which feed the heart. Stasis, incompetent valves, and trauma in the venous circulation cause thrombosis, particularly occurring as a deep vein thrombosis in the peripheral vasculature. When such deposits accumulate in localized regions of the blood vessel, they can restrict blood flow and cause a serious health risk.
In addition to forming in the natural vasculature, thrombosis is a serious problem in “artificial” blood vessels, particularly in peripheral femoral-popliteal and coronary bypass grafts and dialysis access grafts and fistulas. The creation of such artificial blood vessels requires anastomotic attachment at at least one, and usually at at least two, locations in the vasculature. Such sites of an anastomotic attachment are particularly susceptible to thrombus formation due to narrowing caused by intimal hyperplasia, and thrombus formation at these sites is a frequent cause of failure of the implanted graft or fistula. The arterio-venous grafts and fistulas which are used for dialysis access are significantly compromised by thrombosis at the sites of anastomotic attachment and elsewhere. Thrombosis often occurs to such an extent that the graft needs to be replaced within a few years or, in the worst cases, a few months.
A variety of methods have been developed for treating thrombosis and atherosclerosis in the coronary and peripheral vasculature as well as in implanted grafts and fistulas. Such techniques include surgical procedures, such as coronary artery bypass grafting, and minimally invasive procedures, such as angioplasty, atherectomy, thrombectomy, thrombolysis, transmyocardial revasculaturization, and the like.
Of particular interest to the present invention, a variety of techniques have been developed for dissolving clot using thrombolytic agents, such as tissue plasminogen activator (tPA), streptokinase, urokinase, and the like. While such thrombolytic agents can be delivered systemically, the present invention is most particularly concerned with the local delivery of such agents and even more particularly concerned with the local delivery of such agents in combination with mechanical clot disruption.
Thrombolytic agents can be very effective at attacking and dissolving relatively soft clot, such as that formed in deep veins. Such agents, however, require time to act, and local delivery catheters often employ isolation balloons to provide high local concentrations of the active thrombolytic agents. Even with such enhanced concentrations, the agents can take extended periods to act, rendering the treatments lengthy and inefficient. In some instances, extensive regions of clot simply cannot be effectively treated using thrombolytic agents alone. In such cases, it has been further proposed to provide a mechanical element to disrupt the clot while the thrombolytic agents are being delivered. See, for example, U.S. Pat. No. 5,947,985 to Mir A. Imran. This patent describes a catheter having axially spaced-apart balloons for isolating a treatment region within a blood vessel. The catheter includes a port for delivering thrombolytic agent between the spaced-apart balloons and a helical wire for removing clot material from the wall to assist in aspiration. While a promising technique, this catheter is not optimized to enhance delivery and mixing of the thrombolytic agent directly into the clot being treated.
For these reasons, it would be desirable to provide improved apparatus, systems, methods, and kits for disrupting and dissolving vascular clot, particularly soft clot of the type found in deep vein thrombosis. It would be particularly desirable to provide methods and apparatus which can enhance the thrombolytic activity of thrombolytic agents delivered to the region being treated, and even more particularly enhance the direct introduction into and mixing of the thrombolytic agent within the mass of clot within the blood vessel. Such methods and apparatus should preferably both reduce the treatment times required for thrombolytic dissolution of vascular clot as well as improve the mechanical breakdown of that clot into smaller and smaller particles to facilitate removal of the dissolved clot. At least some of these objectives will be met by the inventions described hereinafter.
2. Description of the Background Art
Clot disruption catheters which combine the delivery of thrombolytic agents with mechanical disruption are described in, for example, U.S. Pat. Nos. 5,972,019 and 5,947,985. Other clot disruption catheters are described in, for example, U.S. Pat. Nos. 5,954,737; 5,795,322; 5,766,191; 5,556,408; 5,330,484, 5,279,546; 5,116,352; 5,014,093; and WO 96/01591. Catheters having axially spaced-apart isolation balloons for treating thrombus are shown in, for example, U.S. Pat. Nos. 5,947,985 and 5,279,546 and WO 97/11738. Catheters having helical and non-linear guidewires are described in U.S. Pat. Nos. 5,584,843; 5,360,432; 5,356,418; and 5,312,427. Other patents and patent publications of interest include U.S. Pat. Nos. 5,957,901; 5,951,514; 5,928,203; 5,908,395; 5,897,567; 5,843,103; 5,836,868; 5,713,848; 5,643,228; 5,569,275; 5,549,119; 5,540,707; 5,501,694; 5,498,236; 5,490,859; 5,380,273; 5,284,486; 5,176,693; 5,163,905; 4,923,462; 4,646,736; and 4,445,509; and WO 99/23952 and WO 99/04701. Publications of interest in the medical literature include LeVeen et al. (1992), American Heart Association Poster Presentation; Tachibana (1993)
JVIR S:
299-303; Kandarpa et al. (1998) Radiology 168: 739-744; Bildsoe et al. (1989)
Radiology
171: 231-233; and Ritchie et al. (1986)
Circulation
73: 1006-1012.
SUMMARY OF THE INVENTION
The present invention provides apparatus, systems, methods, and kits for disrupting and dissolving thrombus, also referred to as clot, present in a patient's vasculature, including both the arterial and venous vasculature. The present invention is particularly intended for treating thrombotic disease within the venous vasculature, such as thrombosis in the superficial vein, the central veins, the femoral-popliteal veins, the ilio-femoral vein, and the like. The present invention is also particularly intended for treating arterial thrombotic disease, such as thrombosis in the ilio-femoral artery, the superficial femoral artery, and the like.
The present invention is advantageous in a number of respects. In particular, the methods and apparatus of the present invention will provide improved introduction and mixing of thrombolytic agents into vascular clot, which in turn will improve the efficiency of clot dissolution, including both reducing the time required for dissolution and/or enhancing the degree to which the clot is dissolved, i.e., reducing the particle size of clot achieved at the end of treatment. The reduction of treatment time will reduce both the cost of treatment and the time during which the patient is undergoing the treatment. The improved degree of clot dissolution will reduce the danger of released emboli, which can be a serious risk to the patient. In particular, the methods and devices of the present invention will enhance the mixing of the thrombolytic agent while simultaneously increasing the surface area of the thrombus or clot which is available to the thrombolytic agent being introduced. The release of the thrombolytic agent directly at the point where the thrombus is being disrupted and the increase in available surface area together provide a very significant increase in the thrombolytic activity and co
Demarais Denise M.
Evans Michael A.
Eversull Christian S.
Leeflang Stephen A.
Bacchus Vascular Inc.
Casler Brian L.
Rodriguez Cris
Townsend and Townsend / and Crew LLP
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