Myocardial function in small dogs with chronic mitral regurgitation and severe congestive heart failure.

Systolic myocardial function was assessed in 16 dogs with severe congestive heart failure due to chronic mitral valve fibrosis. End-systolic diameters were measured on echocardiograms and end-systolic volume indices were calculated. Thirteen of the 16 dogs (81%) had normal or only mildly abnormal myocardial function. These data suggested that myocardial failure is not a prominent factor contributing to signs of heart failure in dogs with mitral regurgitation. Because of these data, the routine use of digitalis glycosides to increase cardiac contractility is seriously questioned in dogs with heart failure secondary to chronic mitral regurgitation.