Importance

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Abstract

Hyperthermic treatment of tissue such as cancer tumors, is realized by providing an ohmic heating element on the distal tip of a catheter endovascularly inserted upstream of the tissue. Electrical power is provided to the element for a selected time and degree to raise the temperature of blood to a thermally mediating level such as 42.degree. C., but not to heat the blood so that distal tissues downstream are adversely affected. The element comprises a helical coil heater disposed proximate to the end of a catheter and within an expandable cage. The cage can be selectively deployed by expanding it to maintain the coil out of contact with the vessel walls while still allowing free blood flow. Alternatively a guidewire within an expandable cage can be disposed within the same catheter wherein the heating coil has been wound onto the guidewire or the guidewire is uninsulated at that portion within the cage serves as an electrode to directly heat the blood. Angioplasty without blood flow blockage is realized by expanding a cage instead of a balloon on the catheter. The cage can be selectively expanded by withdrawal of a guidewire temporarily coupled to the catheter tip. The cage can widen the narrowed vascular lumen while still allowing free blood flow and/or contrast agent, and it avoids the risk of balloon deflation failure. The expandable cage can be detachable and implantable as a stent.

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First Claim