Evaluation of Upstream Sampling Method for Quantitating Aortic Regurgitation in Man

Aortic regurgitation was measured from the dye dilution curves recorded simultaneously from the left ventricle and femoral artery following continuous injection of dye into the aortic root. In 18 cases with aortic regurgitant murmur, regurgitant fraction ranged from 7.3 to 145.0% of aortic forward flow, and no regurgitant flow was detected in 4 control patients. Comparing the results of continuous injection method with those of rapid injection method performed in succession, there was a considerable difference of the values between both methods. Reproducibility of measurement was excellent in the continuous method (r=0.98), while poor in the rapid method (r=0.38). The defect of the latter method was primarily due to the inadequate timing of dye injection in relation to the phase of the cardiac cycle. Regurgitant fraction was correlated with diastolic valve area (r=0.78), heart rate (r=-0.46), and peripheral vascular resistance (r=-0.45). There was no close correlation between regurgitant fraction and diastolic pressure gradient from aorta to left ventricle or diastolic time. It is concluded that the continuous injection method can be used as a valid means for estimating aortic regurgitant flow in man and for evaluating hemodynamics in aortic valve disease.