Echocardiographic Evaluation of Mitral Annulus Excursion in Normal Horses

Echocardiographic evaluation of systolic function is important for determination of the hemodynamic state in different cardiomyopathies to provide information for an informed prognosis and proper treatment. During each systole, the heart produces a displacement of the mitral annulus that is quantitatively related to the intensity of the ventricular contraction. This displacement, measured in two-dimensional guided Mmode, constitutes mitral annulus excursion (MAE). This value is a reliable index of left ventricular systolic function. The normal value of the MAE was determined in 30 cardiologically healthy horses. Measurements were made of the displacement of the mitral annulus in the parietal (MAEp) and septal (MAEs) portions, and their indices were calculated as a function of body weight. Statistical correlation was determined for MAEs and MAEp versus body weight. Vol. 2, No. 2, 2004 • Intern J Appl Res Vet Med 110 measured by M-mode echocardiography in normal dogs and in dogs with cardiac disease to evaluate systolic left ventricular long axis performance. However, this index has never been used for routine evaluations or as measure of systolic dysfunction in horses. The purpose of this study was to establish the echocardiographic technique for evaluation of equine MAE, to define its normal reference values for septal and parietal portions, and to establish the index value of MAE relative to body weight. Mean values for MAE in their two portions were compared and the correlation between the values of both excursions and body weight was determined. MATERIALS AND METHODS