Early colour M-mode flow propagation velocity (Vpe) in the left ventricle is a well-known non-invasive index for assessing left ventricular relaxation. However, the utility and determinants of late colour M-mode flow propagation (Vpa) have received little attention to date. Vpa as a representation of the left ventricular vortex travelling velocity during late filling could have a distinct role in differentiating potential subgroups in diastolic failure. The aim of the present study was to establish the normal values of late flow propagation in a healthy population of various ages (18-79 years), and to examine the general and echocardiographic variables that affect Vpa.
Methods: We studied 75 apparently healthy subjects (age range, 18-79 years; 38 women, 37 men) as part of an outpatient clinic check-up screening. General parameters were recorded, including age, gender, height, weight, blood pressure, and heart rate. In addition, conventional grey-scale M-mode, 2D, as well as colour M-mode, 2D, and pulsed wave (tissue) Doppler echocardiographic parameters were obtained in a single centre and using a single operator setting. Backward linear regression analysis (dependent variable: Vpa) was performed to find the optimal model, taking into account multicollinearity and maximum coefficient of determination (R2). Due to the heteroscedasticity of the collected data, a logarithmic transformation was used. In addition, separate linear backward regression analysis was performed for the male and female subgroups.
Results: Vpa values were 26-179 cm/s. The optimal regression model after elimination included the following variables: age (beta = 0.684, P < 0.001), height (beta = 0.521, P < 0.001), gender (beta = 0.343, P < 0.05), left ventricular Vpe (beta = 0.299, P < 0.01), left ventricular posterior systolic (M-mode) wall thickness (beta = 0.288, P < 0.01), interventricular septum thickness diastole (beta = 0.346, P < 0.005), transmitral Doppler E-wave deceleration time apical 4-chamber (beta = -0.297, P < 0.05), and tissue Doppler peak E-wave mitral annulus (beta = 0.459, P < 0.005). The total coefficient of determination (R2) for this model was 0.540 (P < 0.001); 0.673 (P < 0.001) for men and 0.645 (P < 0.001) for women.
Conclusion: Vpa, representing left ventricular vortex travelling velocity during late filling, shows a large range of values in normal healthy subjects. It is mainly depending on age, gender and left ventricular mass. Moreover, substantially different determinants are found between men and women. Further study is required to explore these findings.