Purpose: A decrease in the left ventricular (LV) long-axis early diastolic peak velocity (e') is evident by early-middle age, but it is unknown to what extent this decrease is due to slowing of the speed of active relaxation versus a reduction in LV long-axis excursion during early diastole (EDExc).
Methods: Pulsed-wave tissue Doppler imaging (TDI) signals were acquired from the septal and lateral borders of the mitral annulus in 62 healthy adult subjects of age 18-45 years. EDExc and LV systolic excursion (SExc) were measured as the integrals of the respective TDI signals. The speed of active relaxation was indirectly assessed using time interval measurements related to the TDI early diastolic signal, including the isovolumic relaxation time (IVRT'), the acceleration time (EDAT), and the duration (EDDur). Multiple linear regression analyses were performed to identify the relationships between e', age, EDExc, SExc, and time intervals.
Results: The findings were similar for both LV walls. Age was negatively correlated with e' and EDExc, but was not correlated with SExc, IVRT', EDAT, or EDDur. The closest correlate of EDExc was SExc, and EDExc was independently correlated with both SExc and age. e' was also positively correlated with SExc, but the closest correlate of e' was EDExc, and when combined with EDExc, EDDur became an independent predictor of e'.
Conclusion: The aging-related decrease in e' evident by early-middle age occurs in the absence of aging-related slowing of active relaxation and therefore can be largely attributed to the accompanying reduction in EDExc.
Keywords: Aging; Diastolic function; Left ventricle; Long-axis function; Tissue Doppler imaging.
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