Functional anatomy of severe mitral regurgitation in active rheumatic carditis.

The mechanism of severe mitral regurgitation (MR) due to active rheumatic carditis is ill defined. This study involved 73 patients, aged 7 to 27 years (mean 13), with severe MR and active rheumatic carditis who were subjected to surgery. Sixty-one were studied retrospectively (group 1) and 12 prospectively (group 2). Active rheumatic carditis was diagnosed according to the modified Jones' criteria, morphologic appearances of the heart at operation and histology of the valve. All patients had preoperative 2-dimensional echocardiographic and intraoperative assessment of the mitral valve apparatus. The presence of mitral valve prolapse--defined as failure of leaflet edge coaptation resulting in systolic displacement of the free edge of the involved leaflet toward the left atrium--was determined in all patients. Mitral anular diameter and maximal systolic chordal length were measured at 2-dimensional echocardiography in group 2 patients and compared to values obtained from matched control subjects. Anular and chordal dimensions in 6 of the group 2 patients were correlated with precise measurements obtained at surgery. Mitral valve prolapse involving the anterior leaflet was detected on echocardiography and confirmed at surgery in 69 patients (94%). Mitral anular dilatation was observed at operation in 70 patients (96%). Maximal anular diameter was significantly greater (p less than 0.0001) than in matched control subjects (37 +/- 4 vs 23 +/- 2 mm). The mean anular dimension measured at surgery (36 +/- 3 mm) was similar to that obtained by echocardiography and individual values using the 2 methods correlated well (r = 0.93). Chordal elongation was observed in 66 patients at operation (90%).(ABSTRACT TRUNCATED AT 250 WORDS)