[Thrombosis from prosthetic materials: prevention with different antiaggregatory agents. Low dose aspirin?]

Using an ex vivo shunt in dogs, platelet deposition on 6 prosthetic materials used in the construction of cardiovascular prostheses [highly porous Knitted Dacron (intervascular HP 800, 1,400 ml/cm2/min/120 mmHg), Woven Dacron of low porosity (intervascular LP 200, 200 ml/cm2/min/120 mmHg), Doble Velour Knitted Dacron, Avcothane 51 elastomere and the mesothelial and epipericardial surfaces of bovine pericardium] was quantified. The study of the prevention of platelet thrombi formation on these materials was carried out in 6 groups of 8 animals: group 1 (control), group 2 (5 mg/kg body weight/day acetylsalicylic acid), group 3 (20 mg/kg body weight/day acetylsalicylic acid), group 4 (15 mg/kg body wt/day triflusal plus 5 mg/kg body wt/day dipyridamole), group 5 (15 mg/kg body wt/day triflusal) and group 6 (5 mg/kg body wt/day acetylsalicylic acid plus 5 mg/kg body wt/day dipyridamole). Platelets were labeled with 111In-oxine. The least thrombogenic material was Avcothane 51 elastomere. The only effective treatment for reduction of platelet deposition on the 6 materials was that used in group 2. The treatment used in group 3 only decreased the deposition of platelets on 3 of the 6 materials. The treatments employed in groups 4, 5 and 6 did not significantly diminish the deposition of platelets on any of the materials when compared with the control group. The platelet count was not modified in the animals in groups 2 and 4 while in the rest it decreased after the test.