Real-time coronary blood flow measurement in patients with atrial fibrillation: A study using a catheter-tip Doppler velocimeter

To clarify the influence of changes in the cardiac cycle length (R-R) and aortic pressure on tne coronary blood flow a catheter-tip Doppler velocimeter was applied for 16 patients with chronic atrial fibrillation (11 with valvular heart disease, 2 with coronary artery disease, 2 with cardiomyopathy and one with atrial septal defect). An area under the coronary flow velocity curve during systole (∫S), diastole (∫D) and one cardiac cycle (∫T) for the proximal portion of the left anterior descending artery (LAD: 12 cases) or the right coronary artery (RCA: 10 cases) was calculated in beat-by-beat. Then, the correlations between each area and the R-R, systolic period (S), diastolic period (D) and aortic pressure were assessed. In both the LAD and RCA, prolongation of R-R associated with prolonged D increased ∫D, which caused an increase of ∫T. ∫D correlated with D (p<0.05), but ∫S did not correlate with S, and the degree of change in ∫S or S was much less than that in ∫D or D. R-R or D of the preceding beat correlated inversely (p<0.05) with ∫S in 11 of 12 LAD cases. In the RCA, positive correlations between R-R or D of the preceding beat and ∫S were observed in cases with mitral stenosis (n=6) or coronary heart disease (n=1), but not in other cases; a case with aortic regurgitation or hypertrophic cardiomyopathy, negative and dilated cardiomyopathy, no correlation. In the LAD, aortic systolic pressure did not correlate with ∫S or ∫D. In the RCA, aortic systolic pressure correlated with ∫S in 6 of 10 cases. We concluded that prolongation of the diastolic period increased the coronary blood flow of each cardiac cycle. In the LAD, coronary blood flow during systole was reduced in accord with the prolonged diastolic period of the preceding beat. In the RCA, elevation of aortic systolic pressure tended to increase coronary blood flow during systole.