The toposcopic catheter: a design for maneuvering through tortuous vessels.

The toposcopic catheter is an everting tube that advances within a vessel without moving over the endothelium. It easily passed through simulated tortuous vessels which other catheters could not negotiate and was also successful in the external carotid, vertebral, hepatic, renal and coronary arteries in dogs. The catheter advances to its full length (30 cm) or until wedged in small peripheral arteries.