Estimation of coronary reserve in left anterior descending and circumflex coronary arteries by regional thermodilution technique.

The present study was attempted to determine whether a reduction in regional venous maximal coronary flow can indicate the presence of significant coronary stenosis. The great cardiac vein flow and the coronary sinus outflow were measured simultaneously in 8 open-chest dogs by a continuous thermodilution technique using a triple thermister catheter or two separate thermister catheters. The left anterior descending and circumflex coronary inflows were recorded using electromagnetic flow probes. Successive 70% coronary arterial stenosis maximal coronary flow and coronary reserve decreased significantly in the great cardiac vein and the coronary sinus. Significant correlations were found between the flows in the left anterior descending artery and in the great cardiac vein (r = 0.81) and between those in the circumflex artery and in the coronary sinus minus the great cardiac vein (r = 0.79) throughout the periods of preocclusion, occlusion and reactive hyperemic response. There were no significant changes in heart rate and hemodynamics. Using continuous thermodilution techniques, the inflows of the left anterior descending and the circumflex coronary arteries at a stenosis greater than 70% could be estimated from the changes in regional venous outflows.