Intermittent pressure elevation of the coronary venous system as a method to protect ischemic myocardium

Abstract

Beating heart surgery leaves myocardial areas underperfused and rendered ischemic during brief coronary artery occlusions. In a recent meta-analysis in experimental myocardial infarction, intermittent coronary sinus occlusion (ICSO) proved valid to salvage ischemic myocardium by 30%. Moreover, benefit of this effect can be optimised using coronary venous pressure data. The aim of this study was to evaluate optimisation criteria investigating coronary venous flow data during pressure controlled intermittent coronary sinus occlusion (PICSO). PICSO was performed in 12 adult anaesthetised sheep during occlusion of the left anterior descending (LAD). Additional to coronary sinus pressure (CSP) recordings, venous flow was measured in the great cardiac vein (GCV) via continuous wave Doppler sonography. Experimental studies provide evidence of retrograde flow toward ischemic zone originating from PICSO. Mean antegrade flow, during specific cycle, is significantly higher than the mean retrograde flow (P<0.007). Additionally, differences between various cycles can be considered significant, too (P<0.05). These experimental data support the notion that transient pressure elevation in the coronary venous system recruits collateral flow towards ischemic myocardium. Optimal timing significantly improves the effectiveness of the method. Ease of this intervention makes PICSO capable of protecting myocardial performance during beating heart surgery even without active retroperfusion.