Electrical thermal angioplasty: catheter design features, in vitro tissue ablation studies and in vivo experimental findings.
A prototype electrical thermal tip catheter has been developed for ablation of atherosclerotic plaques. The operating principle is based on establishing an electric arc between a central electrode and the inside of an enclosing metallic tip to convert electrical energy to thermal energy. The metal tip catheter can be heated rapidly and boils water in a saline bath with less than 1 W of power. In vitro studies, using human atherosclerotic aortic segments, demonstrated that effective tissue ablation required more power in saline than in air (more than 9 W vs less than 1 W). The rate of tissue ablation varied with the amount of power delivered and the catheter tip pressure against tissue. In a saline field, 2-mm thickness aortic wall segments were consistently perforated in 3 seconds when 15 W of power and 20 g/mm2 of pressure were applied. Using an atherosclerotic rabbit, in vivo electrical thermal angioplasty (3 W of power for 10-second treatment sequences) was performed in obstructed iliofemoral vessels after mechanical recanalization was attempted. Of the 7 vessels that were more than 50% narrowed (compared with contiguous normal vessel diameter), mechanical recanalization was effective in only 1, but thermal angioplasty resulting in an increased lumen diameter was successful in 6 others. The recanalized segments were 8 to 10 cm; gross morphologic and histologic examination of recanalized vessels demonstrated little or no thermal injury. In addition, significant cholesterol-laden plaques remained in the vessel lumen, which appeared to have been compressed and displaced laterally.(ABSTRACT TRUNCATED AT 250 WORDS)
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Cardiology Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892.
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Bowman
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D000792:Angiography; D000818:Animals; D001018:Aortic Diseases / Q000473:pathology / Q000601:surgery*; D001158:Arteries / Q000473:pathology / Q000601:surgery; D001161:Arteriosclerosis / Q000473:pathology / Q000601:surgery*; D002404:Catheterization / Q000295:instrumentation*; D004598:Electrosurgery / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D011817:Rabbits