Cardiovascular surgery and heparin induced thrombocytopenia

The Authors report a series of 21 cases of heparin induced thrombocytopenia (HIT) observed in a Department of Cardiovascular Surgery. The indication for heparin treatment was a cardiac procedure in 12 cases, peripheral arterial reconstructive surgery in 3 cases and in 6 cases a prevention of embolism. Two routes were used for heparin administration: subcutaneous and intravenous injections. The diagnosis was biological on low platelet counts (p.c.) in 4 cases, in 7 cases a deep venous thrombophlebitis and in 9 cases an acute arterial ischemia complicated the heparin treatment. From the 7th to 15th day after heparin treatment the p.c. had risen to the average value of 46,857/mm3. The diagnosis was clinical in 3 cases, biological with a positive aggregation test in the presence of heparin in 11 cases out of 14 biological tests performed and pathological with observation of white clots in 11 cases. The related mortality rate to HIT was 28.5% of the cases (6 cases). HIT is a rare but severe complication often associated with thrombo-embolic complications. The routine check of p.c. before and after the first week of heparin treatment is reasonable. The negative aggregation test in the presence of heparin does not permit to confirm this diagnosis. The drop in the p.c. between the 6th to 10th day after heparin treatment required an immediate arrest of this type of anticoagulation and replacement with Coumadin. The low molecular weight Heparin may induce cross matching reactions with heparin and therefore is not used as treatment for HIT. In emergency, cardiac surgery with the use of the extra-corporeal circulation device can be performed with success with heparin (2 cases).