An experimental clot model in sheep;: generation of a heterologous clot and its detection in vivo using venography and 125I labelled fibrinogen

An experimental venous Clot model using the lateral saphenous vein of sheep is described. Eight experimental Suffolk crossbred sheep were used. A mixture of human fibrinogen, in some cases labelled with I-125, bovine thrombin and homologous whole blood was placed via a catheter into a surgically isolated segment of the lateral saphenous vein. The resulting heterologous clot was imaged daily for 6 days using venography, or monitored using an external gamma ray detector. Clots were radiographically detectable for the 6 days of the study. They were totally occlusive for a mean of 4.2 days (SD 2.2) and were occlusive in the immediate 24 hour period after Surgery. The fibrin component of the clot was persistent (85 per cent of the initial fibrin{ogen} present after 6 days). Radiographically the clots were seen as filling defects within partially filled vessels, or their presence was inferred from the absence of filling. A collateral blood supply was apparent immediately on vessel occlusion. No adverse effects, evidence of infection or limb oedema were seen. The model provided a reproducible blood clot within the lateral saphenous vein of the sheep. Clot imaging using venography was effective and readily achieved. It is suggested that the model is useful when a stable, intravenous deposit of heterologous (e.g. human) fibrin is required in vivo at a site suitable for venography and radio-nucleid monitoring. (C) 2002 Elsevier Science Ltd. All rights reserved.