Aspects of cardiac venous flow measured by the continuous infusion thermodilution technique.

The continuous infusion thermodilution method for the measurement of cardiac venous blood flow was investigated in 26 patients with angina pectoris. In 10 patients, the correlation coefficients for duplicate flow measurements within 1 min were 0.98 for the coronary sinus (CS) and 0.99 for the great cardiac vein (GCV), with a variation in relation to mean flow of 3.3 and 3.5%, respectively. The average CS drainage in 16 patients amounted to 126 ml/min with the GCV contributing 57% of the total and all other veins (OV) draining into the sinus 43%. Submaximal atrial pacing led to a significant increase in flow in all veins. The mean increase in flow per heart beat was 1.41 ml in the CS, 0.93 ml in the GCV, and 0.58 ml in the OV. The increase in flow per unit (1 X 10(-3) mm Hg - beats) heart rate times blood pressure product was 9.18, 6.97 and 4.71 ml, respectively. The method is suitable for the measurement of rapid changes in total and regional left ventricular blood flow under different conditions. For longer studies spontaneous changes in parameters governing myocardial oxygen demand must be taken into consideration.