Diagnosis of acute rheumatic carditis by endomyocardial biopsy.

This report is the first to document the definitive diagnosis of acute rheumatic carditis by endomyocardial biopsy. An adolescent girl with mitral regurgitation and biventricular congestive heart failure thought to be secondary to rheumatic heart disease was admitted to the hospital for mitral valve replacement. An endomyocardial biopsy performed at cardiac catheterization demonstrated and Aschoff's body in the endocardium and thus confirmed a clinical suspicion of active carditis. Following a course to steroids, the mitral valve was replaced. The surgically excised valve showed gross and microscopic features of acute and chronic valvulitis consistent with rheumatic endocarditis.