Thrombogenic Experience with Intravascular Heat Exchangers

¹ Research and Development Center, Thermo Electron Corporation, Waltham, Massachusetts
² Department of Surgery, Harvard Medical School; Cardiovascular Surgical Research Laboratory, Children's Hospital Medical Center, Boston
³ Department of Surgery, Harvard Medical School; Cardiovascular Division, Sears Surgical Research Laboratories, Boston City Hospital, Boston

We have summarized patency experience with a variety of intravascular prostheses used in evaluating the feasibility of dissipating reject heat from an artificial heart into the circulating blood. Patency tubes, electrical heat exchangers and radioisotope heat exchangers with both straight and helical blood tubes have been fabricated from 304 stainless steel and titanium and implanted in the thoracic and abdominal aortas of mongrel dogs. Internal treatment of the metallic vascular prostheses has included electropolishing, mechanical polishing, acid dipping, ultrasonic cleaning, silicone coating, flocking with Dacron fibrils and coating with graphitebenzalkonium-heparin (GBH). A wide range of patency duration was found even for apparently identical blood tube configurations, material and lumen treatments. However, analysis of the patency duration data for 200 animals indicates that: 1) at radiation exposures (less than 2 rem/hr to the adjacent tissues) and heating indices (<0.6 watt/ kilogram) used in these studies, there is no apparent correlation with thrombosis, 2) infection and sepsis concomitant with percutaneous leads energizing the electrical heat exchangers significantly increase the probability of thrombosis, and 3) the most successful blood tubes were machined from titanium and initially coated with GBH.