Influence of left ventricular relaxation on the pressure half time of aortic regurgitation

Background-The severity of aortic regurgitation can be estimated using pres sure half time (PHT) of the aortic regurgitation flow velocity, but the cor relation between regurgitant fraction and PHT is weak. Aim-To test the hypothesis that the association between PHT and regurgitant fraction is substantially influenced by left ventricular relaxation. Methods-In 63 patients with aortic regurgitation, subdivided into a group w ithout (n = 22) and a group with (n = 41) left ventricular hypertrophy, reg urgitant fraction was calculated using the difference between right and lef t ventricular cardiac outputs. Left ventricular relaxation was assessed usi ng the early to late diastolic Doppler tissue velocity ratio of the mitral annulus (E/ADTI), the E/A ratio of mitral inflow (E/AM), and the E decelera tion time (E-DT). Left ventricular hypertrophy was assessed using the M mod e derived left ventricular mass index. Results-The overall correlation between regurgitant fraction and PHT was we ak (r = 0.36, p < 0.005). In patients without left ventricular hypertrophy, there was a significant correlation between regurgitant fraction and PHT ( r = 0.62, p < 0.005), but not in patients with left ventricular hypertrophy . In patients with a left ventricular relaxation abnormality (defined as E/ ADTI< 1, E/AM< age corrected lower limit, E-DT greater than or equal to 220 ms), no associations between regurgitant fraction and PHT were found, wher eas in patients without left ventricular relaxation abnormalities, the regu rgitant fraction to PHT relations were significant (normal E/AM: r = 0.57, p = 0.02; E-DT< 220 ms: r = 0.50, p < 0.001; E/ADTI < 1: r = 0.57, p = 0.02 ). Conclusions-Only normal left ventricular relaxation allows a significant de cay of PHT with increasing aortic regurgitation severity. In abnormal relax ation, which is usually present in left ventricular hypertrophy, wide varia tion in prolonged backward left ventricular filling may cause dissociation between the regurgitant fraction and PHT. Thus the PHT method should only b e used in the absence of left ventricular relaxation abnormalities.