Heparin-rebound in the early postoperative phase following cardiopulmonary bypass.

The incidence of the 'heparin-rebound' phenomenon after protamine neutralization of systemic heparinization required for cardiopulmonary bypass (CPB) was investigated. Heparin-effect was detected in 43% of patients studied at 2 h, 31% at 4 h, and 37% at 8 h after reversal of circuit heparin on CPB. Heparin-rebound was shown to be associated with a small but significant increase in postoperative bleeding which was not of clinical importance.