Apex sector echocardiography in evaluation of the right atrium in patients with mitral stenosis and atrial septal defect.

Cross-sectional echocardiography utilizing the four chamber apical view was used to evaluate right atrial dimensions as a means of detecting abnormal right heart hemodynamics in 20 patients with mitral stenosis, 5 patients with an atrial septal defect and 10 patients without heart disease. Right and left atrial dimensions on apex echocardiography were 40 mm or less in control subjects. There was a good correlation (r = 0.81) between left atrial size assessed with apex sector and M mode echocardiography. In patients with an atrial septal defect, the left atrium was of normal size on apex sector echocardiography; in patients with mitral stenosis, it was larger on apex echocardiography (59 +/- 9 mm) than on M mode echocardiography (51 +/- 8 mm). The right atrium was enlarged (54 +/- 5 mm) on apex echocardiography in all five patients with an atrial septal defect, but the right ventricle was enlarged in only four. Seventeen of 20 patients with mitral stenosis had an enlarged right atrium (53 +/- 7 mm) on apex echocardiography, whereas 15 had normal right ventricular dimensions (21 +/- 9 mm) on M mode echocardiography. Right atrial size on apex echocardiography was enlarged (54 +/- 6 mm) in 10 of 11 patients with mitral stenosis and pulmonary arterial hypertension. Thus, evaluation of the right atrial dimension with apex echocardiography may be more sensitive than M mode echocardiography in detecting early right heart involvement in specific cardiac conditions.