Rates of Left Ventricular Isovolumic Pressure Rise and Fall from the Aortic Regurgitation Velocity Signal: Description of the Method and Validation in Human Beings

Abstract

Background: Aortic regurgitation results from a pressure gradient across the aortic valve during left ventricular (LV) isovolumic relaxation, LV filling, and isovolumic contraction periods. Assuming the applicability of the simplified Bernoulli equation to this pressure-flow relation and constancy of aortic pressure during LV isovolumic relaxation and contraction periods, one can theoretically obtain estimates of the rates of LV isovolumic pressure fall and rise (ΔP/Δt) from the aortic regurgitation (AR) velocity signal. Methods and Results: Mitral regurgitation (MR) and AR signals were recorded by using the continuous wave Doppler technique in 26 patients with combined mitral and aortic regurgitant lesions. The LV negative ΔP/Δt was obtained by dividing the time taken for the AR velocity to rise from 1 m/sec to 2.5 m/sec into 21 mm Hg, which is the estimated LV pressure drop between these points. In a similar fashion, the LV positive ΔP/Δt was obtained between 2.5 m/sec and 1 m/sec of the fast decelerating portion of the AR signal. The LV negative ΔP/Δt by the AR method ranged from 420 to 3500 mm Hg/sec and correlated well with that obtained by the MR method obtained in a blinded fashion ( r = 0.95, p < 0.0001). The mean (SD) difference between the two methods was 30 (129) mm Hg/sec. Similarly, the LV positive ΔP/Δt by the AR method (range 420 to 2625 mm Hg/sec) correlated closely with that obtained by the MR method ( r = 0.93, p < 0.0001), with the mean (SD) difference between the two methods being 38 (138) mm Hg/sec. Conclusions: Preliminary data presented in this study indicate the feasibility of obtaining a reliable estimate of LV positive and negative ΔP/Δt from the AR velocity profile. Thus the examination of the AR signal may give valuable insights into both LV systolic and diastolic functions. (J Am Soc Echocardiogr 1998;11:631-7.)