M-mode and two-dimensional echocardiography in congenital absence of the pericardium.

The M-mode and two-dimensional echocardiographic features of congenital absence of the pericardium are described in two cases that had been confirmed by clinical and radiological data. The M-mode echocardiogram showed right ventricular dilatation and abnormal systolic motion of the interventricular septum. Echo contrast studies with peripheral injection of saline solution revealed normal persistence of microbubbles in the right side of the heart. Two-dimensional short axis parasternal views showed some dilatation of the right ventricle, with anterior displacement of the left ventricular cavity in systole, which appeared to be wider than the posterior motion of the interventricular septum towards the posterior wall. The resulting positive motion of the interventricular septum toward the transducer could account for the abnormal pattern seen in the M-mode echocardiogram. Congenital absence of the left pericardium has particular echocardiographic features not diagnostic for the anomaly. However, the M-mode and two-dimensional echocardiographic studies, used in conjunction with the echocontrast techniques, seem to help in the differential diagnosis and for excluding associated anomalies.