Introduction: The contribution of the collateral network to myocardial oxygenation under normal circumstances is not clear. However, it is possible that in diseased myocardium this network may be activated and contributes significantly to cardiac blood supply. The purpose of this study was to examine the coronary sinus flow after acute, synchronous, complete occlusion of all epicardial coronary arteries and to investigate methods to increase the flow in the setting of ischaemia.
Methods: In 8 pigs, the coronary sinus flow was measured after complete ligation of all coronary arteries. In two of the 8 experiments adrenaline and dobutamine were infused into the left ventricular cavity, while clamping of the ascending aorta was performed in another three animals in an effort to increase left ventricular systolic pressure.
Results: The mean coronary sinus flow decreased from 36.06 +/- 11.01 ml/min to 5.61 +/- 6.96 ml/min (p < 0.001) after ligation of the coronary arteries. A 67% mean reduction of coronary sinus flow at the first minute after ligation was observed and a progressive decrease of coronary sinus outflow to almost zero within 60 minutes was seen in some experiments. Neither infusion of adrenaline and dobutamine nor ascending aorta clamping increased the coronary sinus flow.
Conclusions: The preservation of coronary sinus flow after the complete occlusion of all coronary arteries indicates that retrograde flow through the collateral network from cardiac chambers may exist. Methods that increase the blood flow through the collateral network may contribute to the improvement of myocardial perfusion in severe coronary insufficiency.