Serendipity and the development of heparin and carbon surfaces

In the early 1960s, bileaflet valves fabricated with polymer housings routi nely thrombosed within a few hours after implantation in the canine heart. In a serendipitous series of events, the authors found a way to bond hepari n to these bileaflet valves using a coating of graphite-carbon and benzalko nium chloride. Over the ensuing 30 years, improved heparin coatings have be en developed by other investigators for bonding to various biomedical devic es; currently, about 25% of oxygenators used in this country utilize hepari n coatings to minimize surface activation of clotting factors. Also, and so mewhat serendipitously, a pyrolytic carbon material developed in the 1960s as a coating for nuclear fuel rods was submitted to the authors' laboratory for possible coating with benzalkonium and heparin. This carbon coating, d eveloped at Gulf General Atomic, Inc, would not bond heparin, but it proved to be the best rigid material available for prosthetic valve construction; more than one million pyrolytic carbon valves have been clinically implant ed over the last 29 years. (C) 1999 by The Society of Thoracic Surgeons.