RESUMO
AIMS: Previous studies using Doppler Tissue Echocardiography (DTE) have suggested that the early-diastolic myocardial velocity behaves as a relatively load-independent index of left ventricular relaxation in patients with cardiac diseases; it is not ascertained if this holds true also in normal human hearts. METHODS AND RESULTS: We assessed the influence of a progressive reduction of preload, obtained by Lower Body Negative Pressure (LBNP), on the diastolic and systolic myocardial waves compared to the inflow patterns estimated in left and right ventricles in nine healthy subjects. LBNP caused a significant decrease in end-diastolic volume, stroke volume and systolic arterial pressure, whilst heart rate increased only at maximum preload reduction; meridional end-systolic stress did not change significantly. The early (E') and late (A') myocardial velocities, at mitral and tricuspid annulus, decreased similarly during lower body suction, so that E'/A' ratio did not change. However, due to reduced early (E) but unchanged late (A) diastolic velocities, the E/A ratio of inflow patterns decreased. Systolic (S') myocardial velocities also decreased during LBNP. LBNP induced greater changes of myocardial diastolic and systolic velocities in the right than in the left ventricle. CONCLUSION: In this study, myocardial E', A' and S' velocities, in both the left and the right ventricle, were significantly affected by preload in healthy subjects. Our results support the usefulness of the E'/A' ratio as a relatively load-independent index of diastolic function.
