We reevaluated our heparin and protamine administration protocol during and after cardiopulmonary bypass (CPB). In 12 patients who underwent cardiac surgery using a heparin-coated circuit under mild hypothermia, heparin concentration was measured with the Hepcon^®/HMS. Before initiating CPB, 1.5mg/kg of heparin was given to maintain the activated clotting time (ACT) at more than 400sec. Patients were divided into two groups. In group I (n=6), heparin was neutralized with an empirical dose of protamine (1.5mg protamine/mg initial heparin). In group II (n=6), the protamine dose was determined by the residual heparin concentration, measured with the Hepcon^®. Patients in group II received a lower dosage of protamine than group I (1.7±0.0 vs. 3.6±0.4mg/kg, p<0.001). There were no significant differences in the intraoperative bleeding, postoperative bleeding and activated clotting time between the groups. By determining the appropriate protamine dosage, this heparin analysis system may be useful in managing CPB.

Between January 1981 and December 1996, we performed valve replacement in 281 patients using bileaflet prosthetic valves in mitral and/or tricuspid positions. Thrombosed valve were seen in 10 patients (7 in mitral, 3 in tricuspid positions). In 5 patients, coumadin had been stopped for several reasons (pacemaker implantation, melena, drug allergy), but in the other 5 patients, anticoagulation was within the therapeutic range at the time of presentation. For thrombolytic therapy urokinase or tissue plasminogen activator were used. The treatment was successful in 5 patients (4 mitral, 1 tricuspid), and unsuccessful in 5 patients (3 mitral, 2 tricuspid). Three of the 5 unsuccessful patients were treated surgically (3 with re-mitral valve replacement, 1 with thrombectomy). Prompt surgical treatment can be used as the first line of therapy for thrombosed valves. Thrombolytic therapy may be useful in some cases of bileaflet valve thrombosis without critical hemodynamic collapse. Doppler echocardiographic assessment of increasing peak velocity and pressure half time is useful for detecting thrombosed valves.