[The mitral valve apparatus in hypertrophic myocardiopathy: observations by transesophageal echocardiography].

INTRODUCTION AND OBJECTIVES

We analyzed the characteristics of mitral valve apparatus by transesophageal echocardiography in a consecutive series of patients with hypertrophic cardiomyopathy.

METHODS

We performed a transesophageal study in 60 patients; 35 of them had intraventricular obstruction at basal state. The following measurements and observations were made in the frontal long-axis transesophageal plane: a) length of both mitral leaflets and dimensions of left ventricular outflow tract that were compared with those obtained from 25 normal subjects; b) structure involved in the systolic anterior mitral motion; c) mechanism of mitral regurgitation, and d) sequence of systolic events.

RESULTS

Compared with control subjects (anterior mitral leaflet: 2.86 +/- 0.3 cm, posterior mitral leaflet: 1.62 +/- 0.2 and 1.7 +/- 0.2 cm, respectively; the mitral leaflets were longer in patients with and without subaortic obstruction (anterior leaflet: 2.3 +/- 0.1; posterior leaflet: 1.07 both, p < 0.01). Systolic anterior motion was observed in 49 patients, with mitral leaflet-septal contact in 87% of patients with obstruction and in 11% of nonobstructive patients (p < 0.01). Structures participating in this phenomenon were: distal portion of the anterior mitral leaflet (77.5%), of both mitral leaflets (18.4%) and anomalous chordae (4.1%); in 5 patients the obstruction was located at a more distal level. Mitral regurgitation was observed in 43 patients; in 37 of them the jet was posteriorly directed in late systole. Patients with hypertrophic cardiomyopathy have longer mitral leaflets with frequent associated abnormalities suggesting that this disease is not confined to myocardium and that leaflet length is not the sole determinant of the obstruction; 2) in almost 80% of patients the systolic anterior motion was produced by the distal anterior mitral leaflet resulting in incomplete coaptation in mid-systole; 3) the sequence of systolic events was ejection/obstruction/leak.