SAEVA Proceedings 2018 4. Proceedings | Page 15

SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa Severity of mitral regurgitation - Clinically insignificant or mild MR results in little or no left atrial and left ventricular enlargement. A left atrium significantly larger than the right atrium or a left atrial appendage in systole equal to or larger than the diameter of the aortic root indicates left atrial enlargement. Marked LA enlargement in horse with severe MR The size of the left atrium and left ventricle depend upon the etiology, initial severity and speed of progression of the MR. With acute onset severe MR, such as that which occurs with the rupture of a major chorda tendineae of the mitral valve, the left atrium has less time to stretch and performance problems associated with pulmonary hypertension may appear with a left atrial diameter of 15 cm or less. A rounded turgid or bulging left atrium is an indication of increased left atrial pressures. The fractional shortening should be increased in horses with severe MR and normal myocardial function. A normal or decreased fractional shortening in a horse with severe MR indicates concurrent left ventricular dysfunction. Hemodynamically severe MR and pulmonary hypertension result in pulmonary artery dilatation. Pulmonary hypertension in horses with severe MR 10