Measurement of Aortic Regurgitation

ALTHOUGH many techniques1-12 have been proposed or utilized for the semiquantitative or quantitative assessment of aortic regurgitation, the most direct approach involves measurement of the regurgitant flow by the recording of indicator concentrations from the left ventricle following injection into the aortic root. This method is theoretically valid13 and had been applied to aortic regurgitation in man12 and to experimental aortic regurgitation in dogs,14, 13 utilizing the sudden indicator injection technique. Attempts to use this technique in our laboratory, however, yielded erratic results. It was reasoned that if the defect in the method was primarily due to the critical dependence of indicator distribution on the timing of the injection or to a beat-to-beat variation in forward or regurgitant stroke output, these difficulties could be overcome by using a continuous infusion of indicator. Therefore, the measurement of aortic