A Comparison of Defective Platelet Count and Aggregation between the Valve Replacement and Cyanotic Congenital Heart Cases during Cardiopulmonary Bypass

Abstract

Platelet count and ADP-induced platelet aggregation were studied in 10 single valve replacement (VR) patients and 10 cyanotic congenital heart disease (CCHD) patients undergoing cardiopulmonary bypass (CPB). The mean platelet count dropped to 78% in VR group and 73% in CCHD group at 30 minutes CPB as compared with the prebypass levels (being corrected for haemodilution). The mean prebypass platelet aggregation value was 65·5% ± 7·5% (Mean ± SEM) in VR group and 56·5% ± 5·2% in CCHD group; the values dropped to 54·2% ± 4·5% and 28·2% ± 4·8% respectively in VR and CCHD groups ( P < 0·01) at 30 minutes CPB. Both groups had a slight further drop at the end of the CPB, but only CCHD group had a further drop in platelet aggregation function after protamine administration. Mean plasma haemoglobin was much higher in the CCHD group than that in VR group at the termination of the bypass ( P < 0·05). Increased blood transfusion volumes were needed and greater blood losses noticed in the CCHD group. A significant negative correlation ( r = 0·5044. P < 0·05) was found between platelet function measured at the termination of CPB and postoperative bleeding. Cardiopulmonary bypass in patients with CCHD appears to be associated with greater platelet dysfunction and this results in more serious haemostatic defects after CPB. It is necessary to have further studies of the defective haemorrhagic status in these patients. More advanced perfusion techniques should be applied to preserve platelets during cardiopulmonary bypass.