Study of posterior left atrial wall motion by echocardiography and its clinical application.

Echocardiographic tracings of posterior left atrial wall motion were examined in 30 normal subjects, 17 patients of mitral stenosis with sinus rhythm and 31 coronary patients with elevated left ventricular end-diastolic pressure. Because of the plane of the posterior left atrial wall motion and the angle of the sound beam, usually the postero-inferior portion of the left atrial wall was recorded. In normal subjects, there were 3 positive waves (A,C,V waves) and 2 negative waves (X and Y waves). The A wave during atrial contraction period occurred in the closing motion of the mitral valve and was initiated by a slight negative wave. The fourth heart sound was consistent with the ascending limb of the A wave. The C wave coincided with the first heart sound followed by the pronounced negative depression (X wave). The X trough coincided with the beginning of the mitral valve opening in early diastole and was the deepest point in the motion curve. The V wave was a peaked anterior motion during rapid filling period and followed by the third heart sound. The Y wave was a slight negative depression following the V wave, and its trough occurred when the both leaflets of the mitral valve assumed a semiclosed position. In both mitral stenosis and coronary artery disease, significant increase (p less than 0.01) of the A wave excursion and significant decrease (p less than 0.01) of the V wave excursion were observed, resulting in marked increase (p less than 0.01) of the A/V ratio. The slope of the ascending limb of the V wave was also decreased apparently in both conditions. These findings might reflect increased resistance to left atrial emptying in mitral stenosis and decreased left ventricular filling rate in coronary artery disease. This study shows that echocardiographic examination of the posterior left atrial wall motion is feasible and useful in estimating the presence of either mitral stenosis or decreased left ventricular filling rate.