Influence of exercise on coronary sinus blood flow determinations

Consecutively measured values of coronary sinus blood flow were compared to assess the reproducibility of the coronary sinus thermodilution technique. Values measured at rest and during exercise were evaluated and the influence of the respiratory cycle on reproducibility was studied. Correlation of consecutive values revealed a coefficient of 0.94 at rest and 0.93 during exercise. Differences between mean values of consecutive measurements were nonsignificant. A comparison of the coefficients of variation at rest (8.50 +/- 7.09) and exercise (8.02 +/- 4.75) revealed no significant difference. Variation about mean coronary sinus blood flow due to inspiration and expiration was similar at rest and during exercise (42% and 37%, respectively). Provided that critical variables are closely monitored, the coronary sinus thermodilution technique is a highly reproducible technique in a clinically feasible setting.