Of these 11 patients, 2 patients had positive HIT antibodies at the 656 Ann Thorac Surg ANTICOAGULATION DURING CARDIOPULMONARY BYPASS 2018;105:650 62 REPORT time of operation. One patient had an ischemic foot, likely related to an intraaortic balloon pump. Three patients (27%) died during the postoperative period (range, 3 months to 1 year) although none of the deaths was attributed to HIT thrombosis. Other case reports and smaller series are summarized in a practice guideline by the American Society for Apheresis, although recom- mendations regarding CPB are limited [52, 73]. Iloprost (prostacyclin analogue) was used in several studies of HIT patients to inhibit platelet activation dur- ing cardiac surgery [76]. In a large retrospective analysis of 1,518 consecutive cardiac surgery patients, Palatianos and associates [77] identi ed 10 patients with clinical symptoms of HIT with PF4-heparin antibodies and compared them with 10 randomly selected control sub- jects. Patients presenting with HIT received a protocol of iloprost infusion, supplemented with norepinephrine as needed, in conjunction with heparin. The postoperative reduction in platelet count was less in the iloprost group (12.5%  8.7%) versus the control group (38.1%  15.2%), and no thrombotic complications were detected. In another small study (n 10) by Koster and associates [78], heparin was used in conjunction with a tiro ban infusion during CPB. There was no clinical or laboratory (D- dimer) evidence of thrombosis or excessive bleeding. The use of argatroban has been reported with patients requiring renal replacement therapy. Given that renal clearance is an important means of bivalirudin excretion and inactivation, argatroban should be limited to these exceptional circumstances, given that excessive bleeding is the norm [79 83]. Patients who are seropositive for heparin antibodies are at increased risk of both thrombosis and bleeding (asso- ciated with heparin alternatives). 