Age-dependency of left ventricular filling dynamics and relaxation as assessed by pulsed Doppler echocardiography

Left ventricular diastolic function was assessed from transmitral flow velocity curves as measured by Doppler echocardiography in healthy individuals aged 21-69 years, each decade comprising 12 subjects. By ageing, progressive changes in the various filling parameters were observed. When comparing the youngest and oldest age groups, the ratio between peak velocities in early and late diastole decreased from 2.0 +/- 0.3 to 1.2 +/- 0.3 (P less than 0.001). The filling fraction of first third of diastole decreased from 54 +/- 5% to 45 +/- 4% (P less than 0.001). Isovolumic relaxation time increased from 61 +/- 11 ms to 77 +/- 12 ms (P less than 0.01). Correlation coefficients of velocity ratio, filling fraction and isovolumic relaxation time vs. age were r = -0.71 (P less than 0.001), r = -0.56 (P less than 0.001) and r = 0.44 (P less than 0.001), respectively. When isovolumic relaxation time and age were used together in multivariate regression analysis, only age was an independent predictor of velocity ratio and filling fraction. Stroke volume, peak velocity in left ventricular outflow tract, heart rate and systolic blood pressure were similar in all age groups. Thus, velocity ratio and filling fraction indicated a relative filling shift towards late diastole by ageing and were more sensitive than systolic parameters in reflecting age-related changes in cardiac function. The changes could be explained neither by delayed relaxation nor by change in systolic parameters. When using Doppler echocardiography for evaluation of left ventricular filling, age-matching of reference groups is necessary.