Platelet accumulation on mature Dacron grafts in man.

Prosthetic graft occlusion is most frequent in the early postoperative period when the luminal surface is highly thrombogenic. It is generally believed that graft maturation ultimately results in a non-thrombogenic surface. The accumulation of 111-indium-labelled autologous platelets in Dacron aortofemoral grafts has been measured 1 week following surgery and at intervals of 6 months to 1 year. Platelets from 9 patients were labelled with 111-indium oxine and re-injected. Isotope emissions over the graft and a reference site (aortic arch) were measured daily for 8 days and gamma camera images taken on alternate days. Graft thrombogenicity was calculated as the daily rise in the graft: reference ratio of emissions. All grafts, regardless of age, accumulated platelets and were imaged by gamma camera. Mean thrombogenicity (+/- s.e.mean) 1 week after surgery was 0.21 +/- 0.04 compared with 0.08 +/- 0.03 at follow-up (P less than 0.01). The platelet survival during the early study was reduced at 6.8 +/- 0.6 days but recovered to a value of 8.6 +/- 0.8 days (P less than 0.01) at follow-up. Further grafts, 2, 5 and 9 years old, were studied and all accumulated platelets, especially near the anastomoses. Platelet accumulation on Dacron grafts does diminish with time but persists beyond the period of altered platelet survival and perhaps indefinitely.