Assessing Endothelial Responsiveness After Cardiopulmonary Bypass: Insights on Different Perfusion Modalities

Abstract

Objective: Cardiopulmonary bypass (CPB) exerts several deleterious effects on inflammatory pathways. Most of these can be related to an endothelial insult leading to endothelial dysfunction. To date, the degree of endothelial damage only has been evaluated on a cellular and molecular level, but no studies exist looking at the functional effects of CPB on the endothelium.

Design: Previous studies hypothesized a negative effect of continuous flow as opposed to the physiologic pulsatile flow. The aim of the present retrospective study was to investigate how different perfusion modalities during CPB (ie, continuous v pulsatile flow) or its avoidance differently impact endothelial function.

Setting: Cardiovascular operating room and intensive care unit of a large tertiary University Hospital in Monza, Italy.

Participants: Flow-mediated dilatation (FMD) of the brachial artery was assessed in 29 patients undergoing elective myocardial revascularization. Ten patients receiving continuous-flow CPB, 10 receiving pulsatile-flow CPB, and 9 scheduled for beating-heart revascularization were studied.

Interventions: Patients were studied at baseline (after induction of general anesthesia), after CPB upon intensive care unit (ICU) admission after surgery, and on the first postoperative day before discharge from the ICU (on average, 24 hours after CPB discontinuation).

Measurements and main results: The continuous-flow CPB group demonstrated a significant reduction in FMD after CPB, (12.8% ± 9.7% v 1.6% ± 1.5%, p<0.01), which lasted up to the first postoperative day (5.9% ± 4.1%). On the other hand, FMD did not change in the pulsatile-flow group (12.5% ± 10.5%, 11.0% ± 7.2%, and 16.6% ± 11.7%, respectively). FMD also was unaffected in the beating-heart group, thus suggesting a direct effect of CPB itself on endothelial function.

Conclusions: In conclusion, in this study population of adult patients undergoing elective coronary revascularization, continuous-flow CPB markedly impaired endothelial function, although this was not the case with pulsatile-flow CPB. This study posed the rationale for further investigations on the potential value of FMD to predict cardiovascular events in these patients.

Keywords: cardiopulmonary bypass; continuous flow; endothelial function; flow-mediated dilatation; pulsatile flow.