Amplitude and velocity of mitral annulus motion in rabbits.

Objective: During recent years, the amplitude and the maximal systolic velocity of the mitral annulus motion (MAM) have been established as indices of the left ventricular systolic function and the maximal diastolic velocity of the annulus motion has been suggested as an index of diastolic function. The main aims of the present study were to investigate the feasibility of these techniques in rabbits and to investigate age-related changes concerning these variables. Methods: Twenty-one New Zealand white rabbits were investigated by echocardiographic M-mode and pulsed tissue Doppler. One subgroup (I) included 11 still-growing, 3.0 ± 0.2 month-old, animals and another group (II) included 10 young grown up rabbits, 12.1 ± 1.5 months old. Results: The amplitude (4.8 ± 0.6 and 3.5 ± 0.3 mm, respectively) and maximal systolic (98 ± 14 and 66 ± 7 mm/s, respectively) and diastolic (111 ± 21 and 80 ± 12 mm/s, respectively) velocities of the MAM were significantly (P < 0.001) higher in group I than in group II, despite a bigger heart in the animals in the latter group. A coefficient of variation of <5% was found for both inter- and intraobserver variability for both amplitude and velocities. Conclusions: The amplitude and velocities of MAM are easily recorded in rabbits with excellent reproducibility and the changes with age seem to be very similar to those in humans. These noninvasive M-mode and tissue Doppler methods are therefore suitable for the investigation of left ventricular function in experimental studies in rabbits. (ECHOCARDIOGRAPHY, Volume 21, May 2004)