Cardiopulmonary bypass using heparin surface treatment: influence on memory and neurological deviations

Objectives

Cerebral dysfunction associated with cardiac surgery and cardiopulmonary bypass (CPB) manifested as focal ischemic injury and diffuse encephalopathy is a devastating complication. Emboli from the surgical field and hypoperfusion have been suggested as possible causes. The present investigation was undertaken in order to investigate the role of heparin coatings in CPB as means of ameliorating neurological trauma.

Methods

Three hundred patients admitted for routine aorta-coronary bypass surgery were prospectively randomized into four groups based on Carmeda Bioactive Surface and Baxter Duraflo II coatings (ACT > 250 s) for CPB, each with an assigned uncoated control (ACT > 500 s). Outcome was determined as clinical neurological deviations, release of S100, perioperative implicit and explicit memory performances, with a questionnaire follow up after 4 months.

Results

The incidence of clinical neurological deviations ranged from 4 to 8%, with no intergroup differences (P = 0.738). Concentration of S100 was significantly (P = 0.001) elevated (0.76 ± 0.03 μg/l) in all four groups during CPB and remained so (0.39 ± 0.03 μg/l) 7 h postoperatively. A notably higher release of S100 per CPB was observed in the Baxter control group (P < 0.05). No perioperative differences in implicit and explicit memory function between groups were detected. At 4 months, patients in the Baxter control group reported a more depressed memory (P < 0.05) than did those in other groups. Memory function as experienced by next of kin demonstrated no intergroup differences, however.

Conclusions

The role of heparin coating in CPB as a tool to prevent memory dysfunction and neurological deviations is not conclusive, despite a less favourable outcome in terms of S100 release and subjective rating of memory function for patients in the Baxter uncoated control group.