RF84 THE ROLE OF FLOW MEASUREMENT DURING AORTIC CROSS-CLAMP IN CORONARY SURGERY

Abstract

Background and aim: Transit-Time Flow Measurement (TTFM) verified by imaging represents a unique tool for the study of the physiopathology of coronary circulation. We evaluate TTFM during aortic cross clamp comparing it with the MGF after protamine and to evaluate its relationship with previous myocardial infarction on the LAD territory. Methods: Retrospective analysis of TTFM values and clinical charts of 57 patients form June 2016 to April 2017. Results: The median MGF values measured during aortic cross-clamp are significantly higher than the MGF measured immediately after cross clamp release and after protamine administration (35 ml/min (20-53) vs 15 ml/min (11-22) vs 20 ml/min (13-29) respectively = 0.0003). Thirteen patients (22%) had a previous MI on the LAD territory. There is a strong correlation between the flow of the graft on the LAD during aortic cross clamp compared to the flow immediately after the release of the clamp itself in case of previous myocardial infarction (MI). Fig 1 A-B) Conclusions: Flow measured during cardioplegic arrest and aortic cross clamp causes a significant increase in myocardial blood flow demand related to ischemia and very low coronary vascular resistance due to the absence of muscular contraction and arteriolar tone modification. Moreover, the MGF during aortic cross clamp is correlated to the MGF after clamp release in case of previous MI. The evaluation of scar extent using nuclear magnetic resonance can help to predict the expected flow after surgical revascularization.