Coagulation Patterns in Bovine Left Heart Bypass with Phospholipid Versus Heparin Surface Coating

Abstract

The current study was designed to evaluate tubing sets with either polymeric phospholipids or ionically bound heparin in six bovine experiments (body weight, 70 ± 5 kg). No heparin was given systemically. Left heart bypass was started with 300 ml of clear priming solution and maintained over 6 hours (50 ml/kg/min). Coagulation studies included platelet counts, activated coagulation time (ACT), thrombin time (TT), fibrinogen (Factor I), antithrombin III (AT III), and fibrinopeptide A (FPA). Normalized platelet levels dropped from 100 ± 12% before to 86 ± 13% after 6 hours of left heart bypass for heparin, compared with 100 ± 46% to 90 ± 44% for phospholipid coating (NS). The ACT increased from 146 ± 7 sec at 10 min to 159 ± 16 sec after 6 hours for heparin, compared with 122 ± 4 to 126 ± 5 sec for phospholipid (p<0.05). Thrombin time changed from 18 ± 0 sec before to 19 ± 1 sec after 6 hours for heparin, as compared with 16 ± 1 sec to 18 ± 1 sec for phospholipid (NS). Factor I levels decreased from 1.5 ± 0.3 g/L to 1.3 ± 0.1 g/L for heparin, compared with 1.5 ± 0.2 g/L to 1.4 ± 0.3 g/L for phospholipid. Antithrombin III levels changed from 102 ± 26% to 91 ± 7% for heparin, compared with 123 ± 12% to 118 ± 12% for phospholipid. Fibrinopeptide A levels changed from 100 ± 60% to 130 ± 13% for heparin, compared with 100 ± 11% to 99 ± 6% for phospholipid (P<0.05). No macroscopic red clots were found in either group. Surfaces with polymeric phospholipids appear to be as thromboresistant as those with bonded heparin.