Early mitral deceleration and left atrial stiffness

Left ventricular (LV) filling deceleration time (DT) is determined by the sum of atrial and ventricular stiffnesses (K_LA + K_LV). If K_LA, however, is close to zero, then DT would reflect K_LV only. The purpose of this study was to quantify K_LA during DT. In 15 patients, K_LV was assessed, immediately after cardiopulmonary bypass, from E wave DT as derived from mitral tracings obtained by transesophageal echocardiography and computed according to a validated formula. In each patient, a left atrial (LA) volume curve was also obtained combining mitral and pulmonary vein (PV) cumulative flow plus LA volume measured at end diastole. Time-adjusted LA pressure was measured simultaneously with Doppler data in all patients. K_LA was then calculated during the ascending limb of the V loop and during DT. LA volume decreased by 7.3 ± 6.5 ml/m² during the first 4/6 of mitral DT, whereas LV volume increased 9.4 ± 8.4 ml/m² (both P < 0.001). There was a small amount of blood coming from the PV during the same time interval, with the cumulative flow averaging 3.2 ± 2.4 ml/m² (P < 0.001). Mean LA pressure was 10.0 ± 5.1 mmHg, and it did not change during 4/6 DT [from 7.8 ± 4.3 to 8.0 ± 4.3 mmHg, not significant (NS)], making K_LA, which averaged 0.46 ± 0.39 mmHg/ml during the V loop, close to zero during DT [K_LA(DT): from -0.002 ± 0.08 to -0.001 ± 0.031 mmHg/ml, NS]. K_LV, as assessed noninvasively from DT, averaged 0.25 ± 0.32 mmHg/ml. In conclusion, notwithstanding the significant decrement in LA volume, K_LA does not change and can be considered not different from zero during DT. Thus K_LA does not affect the estimation of K _LV from Doppler parameters.