Heparin Induced Platelet Aggregation Presentation and Surgical Consequences

Abstract

Heparin induced thrombocytopenia and its vascular complications were identified in 25 patients. Aggregation studies performed using ADP and/or heparin in these patients were compared with responses in 18 normal. individuals. The specific aggregating factor was demonstrated in plasma. Other findings of note were normal fibrinogen, minimal elevation of fibrin split products, a normal or slightly prolonged prothrombin time and severe thrombocytopenia. Arterial and venous thrombosis required surgery in seven patients, four of whom required major amputation. Although an antibody has not been identified, the time of development of this phenomenon suggests an immune response. Only those patients who had previous exposure to heparin developed this phenomenon in less than six days. Thrombotic complications occurred with either bovine lung or porcine gut preparations from different manufacturers and appeared following both subcutaneous and intravenous administration. Electron microscopy of clots removed from four patients revealed characteristic platelet fibrin thrombi. Early recognition, prompt discontinuance of heparin and the use of platelet antiaggregants will prevent disastrous consequences. All patients undergoing heparin therapy should be carefully observed for thrombocytopenia with specific platelet aggregation studies when appropriate.