Peak systolic mitral annulus velocity reflects the status of ventricular-arterial coupling-theoretical and experimental analyses

Background: Peak systolic mitral annular velocity (S(m)) measured by tissue Doppler echocardiography has been recognized as an independent predictor of mortality in patients with heart failure and in the general population. However, the mechanical determinants of S(m) remain poorly defined.

Methods: A theoretical model of S(m) was derived, which indicates that S(m) is affected positively by left ventricular (LV) contractility and preload and inversely by LV afterload and ejection time (EJT). In 16 anesthetized dogs, S(m), LV volume, and LV pressure were measured using sonomicrometry and catheter-tip micromanometry. LV contractility, preload, and afterload were indexed by the end-systolic pressure/volume ratio (E(es)'), end-diastolic volume (V(ed)), and effective arterial elastance (E(a)), respectively. LV contractility, loading conditions, and heart rate were varied over wide ranges, and a total of 76 data sets were obtained for S(m) (1.2-9.1 cm/sec), E(es)' (1.5-17.6 mm Hg/mL), V(ed) (11-99 mL), E(a) (3.6-58.4 mm Hg/mL), EJT (100-246 msec), heart rate (66-192 beats/min), and the ventricular-arterial coupling ratio (E(es)'/E(a); 0.2-3.0).

Results: The theoretical model accurately predicted S(m) (R(2) = 0.79, P < .0001). By univariate analysis, S(m) was correlated significantly with E(es)' (R(2) = 0.64, P < .0001) and with the reciprocal of E(a) (R(2) = 0.49, P < .01). V(ed) and EJT did not affect S(m). E(es)'/E(a) was correlated strongly with S(m) (R(2) = 0.73, P < .0001). E(es)' and the reciprocal of E(a) were not correlated with each other.

Conclusions: LV contractility and afterload independently determine S(m). The effects of LV preload and EJT on S(m) might be small, even though they are theoretically associated with S(m). S(m) strongly reflects the status of ventricular-arterial coupling.