Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-05-19
2003-01-21
Walberg, Teresa (Department: 3742)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S508000, C604S509000, C604S020000, C604S022000, C600S003000
Reexamination Certificate
active
06508784
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to improved medical devices and methods for use. More particularly, the present invention relates to a balloon catheter having adjustable capability for positioning and orienting the tip section resulting in more effective radioactive treatment of eccentric atheroma in a patient for use in association with coronary, renal, cerebral, and peripheral angioplasty/stenting.
BACKGROUND OF THE INVENTION
The primary methods of intervention for coronary artery diseases are coronary artery bypass graft surgery (CABG) and percutaneous transluminal coronary angioplasty (PTCA). In PTCA, a catheter equipped with an inflatable balloon is threaded intravascularly to the site of atherosclerotic narrowing of the vessel. Inflation of the balloon with concomitant compression of atheroma enlarges the atherosclerotic narrowing and enlarges the lumen by stretching the vessel wall. PTCA has emerged as a very effective alternative to CABG. That is, it is less invasive, has lower patient risks, and costs less than CABG.
The principle limitation of angioplasty is restenosis, a re-narrowing of the treated vessel to less than 50% of its original size. Studies have shown that restenosis affects 25-45% of PTCA patients, requiring re-intervention at some point in the first six months post the initial procedure. Stents have proven highly effective at reducing both elastic recoil of the arterial wall and vascular remodeling by holding the vessel open. Restenosis rates after stenting have been reported in the 20-30% ranges due to primarily intimal hyperplasia. Intimal hyperplasia is a physiological response to injury, similar to the scarring that occurs in wound healing. During the first few weeks after angioplasty, cells multiply on the inside of the artery, causing the inner lumen to shrink. Several approaches have been suggested and tried to reduce the restenosis rate with mixed results, including atherectomy, laser, cryo-ablation, thermo-ablation, ultrasound, calcium antagonists, fish oils, steroids, or the like.
Radiation seems to be effective at preventing smooth muscle cell proliferation by breaking the strands of DNA in living cells. One of the current radiation therapies is first to advance a flexible delivery balloon catheter through an artery or a vein of a patient until the distal tip is at or near the lesion region of the treated vessel. Subsequently, a treatment apparatus, comprising a wire or a small catheter having a radiation source at the tip is advanced through the delivery balloon catheter until the radiation source is disposed at the lesion region. The radiation source is held at the lesion region for a predetermined treatment period calculated to deliver an effective radioactive dose of radiation. Thereafter the treatment apparatus and the delivery balloon catheter are then withdrawn.
Hess in U.S. Pat. No. 5,411,466 teaches a method and apparatus for treating restenosis by positioning a radioactive dose to the region after angioplasty to inhibit restenosis. The catheter has at its distal end a radioactive source, wherein the source is maneurable to the site of a lesion allowing the site to be exposed to the radiation dose that will affect smooth muscle cells such that the rapid growth of such cells can be prevented, thereby controlling restenosis. This patent, however, does not address non-uniform irradiation, nor does it teach means for positioning and centering the radiation dose for effective irradiation on an essentially eccentric atheroma lesion region.
Treatment apparatus, such as a catheter or a wire has been disclosed. For example, U.S. Pat. No. 5,199,939 to Dake et al. discloses a radioactive catheter having a plurality of cylindrically shaped, radioactive pellets longitudinally spaced apart inside the lumen of the catheter. However, non-centering wire-carried radiation sources are sub-optimal in performance which has been disclosed by Dake et al. in U.S. Pat. No. 5,199,939 and Bradshaw in U.S. Pat. No. 5,643,171. Therefore, it would be highly desirable to provide a radiation delivery system that would assure that the source is somehow centered in the vessel for an essentially uniform atheroma lesion type or adjustably positioned about the center of the vessel for an eccentric atheroma lesion type.
Current balloon dilatation catheters employ a fixed or movable steerable guidewire which negotiates the serpentine coronary vasculature in an atraumatic fashion to provide a path for the passage of the balloon catheter. Apparatus for positioning a catheter distal tip is known and well practiced. U.S. Pat. No. 4,793,359 to Sharrow discloses a balloon near the tip of an angioplasty catheter for accurately establishing the position and orientation of the distal tip within an artery in response to the balloon dilation. The balloon comprises a distal wall portion substantially perpendicular to the central axis so as the catheter tip is placed in centered, coaxial relation to the balloon when the balloon is inflated. However, the atherosclerosis plaque is generally asymmetrically distributed around the artery wall. In an atherosclerotic artery, the balloon catheter as disclosed by Sharrow does not have an adjustable means for effectively positioning the distal tip.
U.S. Pat. No. 5,122,125 to Deuss discloses an angioplasty catheter having at least three radially protruding elements constructed of very soft material at its end portion so that a very great stability of the end portion is achieved against the surrounding vessel wall. However, the catheter still suffers the capability for adjusting its tip position and orientation for more effective irradiation therapy.
U.S. Pat. No. 5,179,961 to Littleford discloses a separate flexible tube having a peripherally expandable zone at the distal end of the tube so as to center and stabilize the flexible tube in place. A treatment catheter is then passed through the lumen of the flexible tube for tissue treatment. However, Littleford does not disclose a delivery catheter having an adjustable means for independently adjusting each of the expandable elements for effective positioning of the distal tip.
Aliahmad et al. in U.S. Pat. No. 5,295,960 discloses a catheter with balloon material or a membrane disposed interiorly of the catheter body in the inflation lumen so that the balloon material can be inflated to form at least one exterior balloon through holes of the catheter body at the end or the side of the catheter body. As disclosed, separate balloons formed from a single membrane can be deployed through respective openings circumferentially spaced or axially spaced. However, the balloon material or membrane does not have an adjustable means for independently adjusting each of the expandable balloons. The balloon material is not an integral part of the distal catheter body and may separate from the catheter body unexpectedly.
Inflation of conventional dilatation balloons completely blocks the artery, and thus interrupts distal coronary blood flow. Typical inflation time for radioactive treatment may range from 3 minutes to 60 minutes. Maintenance of coronary perfusion during dilation would greatly enhance the safety of coronary angioplasty, particularly in vessels serving large areas of myocardium. Therefore, it would be desirable for a radioactive treatment apparatus or delivery balloon catheter to provide for continuous blood flow (perfusion) past the stenotic region in the target coronary vessel.
U.S. Pat. No. 5,087,247 to Horn et al. and No. 5,295,995 to Kleiman disclose perfusion dilatation catheter having some clearance between the inflated balloon and the vessel wall so that continuous perfusion is maintained. Particularly, U.S. Pat. No. 5,295,995 shows an inflatable non-circular balloon, wherein the balloon tip has at least two substantially rounded axial protrusions or apices which, upon expansion of the balloon, come into apposition with the walls of the target vessel and form blood flow paths around the protrusions. The inflated balloon does not have adjustable means for effec
Dahbour Fadi H.
Walberg Teresa
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