Minimized cardiopulmonary bypass reduces retinal microembolization: a randomized clinical study using fluorescein angiography.

Background: The use of minimized cardiopulmonary bypass (MCPB) circuits has recently increased in an attempt to reduce the adverse effects of CPB. This prospective randomized study aimed to determine the effects of MCPB on retinal microembolization and related inflammatory, coagulation, and endothelial markers compared with conventional extracorporeal circulation (CCPB) among patients undergoing coronary artery bypass graft surgery.

Methods: Forty patients entered, and 37 patients completed the study. After the induction of anesthesia and immediately after the termination of CPB, standardized retinal fluorescein angiographs and digital images were obtained on both eyes and analyzed in a blinded fashion in terms of the CPB circuit. Blood samples for inflammatory, coagulation, and endothelial markers were collected at eight time points until the third postoperative day.

Results: Postperfusion retinal fluorescein angiographs revealed microembolic perfusion defects in 2 of 18 in the MCPB group and in 9 of 18 in the CCPB group (p=0.027 [11% vs. 50%, difference 39%, confidence interval: 0.087 to 0.613, p=0.029]). Activation of polymorphonuclear leukocytes as measured with polymorphonuclear elastase was significantly decreased in the MCPB group. Other markers of inflammation, coagulation, and endothelial dysfunction increased comparably in both groups during CPB.

Conclusions: Retinal microembolization was found to be decreased after the use of minimized CPB compared with CCPB, suggesting a decreased embolic load to the brain after MCPB.