Mitral annulus motion as determined by M-mode echocardiography in normal dogs and dogs with cardiac disease

M-mode echocardiography was used to assess apical mitral annulus motion (MA M) in 103 normal dogs and 101 dogs with cardiac disease, to obtain informat ion on systolic left ventricular long axis function. in normal dogs, a clos e relationship was found between MAM and body weight (r = 0.80, P < 0.001), There was a weak correlation between MAM and heart rate (r = -0.25, P < 0. 05), but no correlation between MAM and age or left ventricular shortening fraction (P > 0.05), Mean MAM (95% confidence intervals) were established f or normal dogs of differing body weight, and were 0.70 cm (0.65 to 0.75) in dogs < 15 kg, 1.08 cm (1.03 to 1.13) in dogs weighing 15 to 40 kg, and 1.5 1 cm (1.21 to 1.81) in dogs > 40 kg. "Cut-off" values to define decreased M AM for normal dogs of differing body weight were 0.45 cm (dogs < 15 kg), 0. 80 cm (dogs 15-40 kg), and 1.20 cm (dogs > 40 kg), In dogs with cardiac dis ease, median MAM was normal in mitral valve endocardiosis or aortic stenosi s, but significantly decreased (P < 0.05) in dilated cardiomyopathy, All do gs with mitral valve endocardiosis (n = 54) or aortic stenosis (n = 26) had MAM above the above-mentioned "cut-off" values, suggesting normal or incre ased left ventricular longitudinal systolic shortening, whereas 81% (17/21) of dogs with dilated cardiomyopathy had MAM below the "cut-off" value, ind icating decreased long axis systolic function. It is concluded that MAM may be used to evaluate systolic left ventricular long axis performance in dog s and may add useful information on global left ventricular contraction dyn amics.