Effect of defibrinogenation on the early patency rate of experimental small calibre arterial grafts.

The effect of defibrinogenation with Arvin was studied in a new animal model of early thrombosis of a 3 mm diameter polytetrafluoroethylene (PTFE) graft with a poor run-off. Fifteen control animals were compared with fourteen animals treated with subcutaneous Arvin 20 units kg-1 body weight day-1, starting 2 days before surgery and continuing for 2 days postoperatively. The peroperative fibrinogen level in the controls was 2.8 +/- 0.9 gl-1 compared with 0.4 +/- 0.3 gl-1 in the treated group. There was no significant difference in the peroperative or postoperative platelet count or haematocrit value between the two groups. Plasma viscosity and whole blood viscosity (at a low shear rate of 0.7s-1) were significantly less during and after surgery in the defibrinogenated group. The degree of defibrinogenation in these animals produced no problems with haemostasis during surgery or in the postoperative period. The cumulative patency rates of the controls at 24 h, 48 h, and 4 days were 43 per cent, 28 per cent and 28 per cent compared with 86 per cent (P less than 0.05), 73 per cent (P less than 0.05) and 73 per cent (P less than 0.05) respectively in the defibrinogenated group. In this model of a narrow PTFE graft with a poor run-off, defibrinogenation was a safe and effective method of improving early patency of small calibre arterial grafts.