Reflected Ultrasound in the Assessment of Mitral Valve Disease

Abstract

An ultrasound beam directed into a medium of uniform acoustical impedance will travel in a straight line, but a portion of the waves will be reflected at the interface of a medium of different acoustical impedance. A time-distance curve of motion has been obtained from the heart by recording the echoes returned to a send-receive ultrasound transducer applied in the third, fourth, or fifth left interspace. A characteristic curve having two anterior peaks during each cardiac cycle was obtained in the 25 normal patients studied. One peak follows the P wave of the electrocardiogram and is not seen in atrial fibrillation. The other peak of motion toward the anterior chest is followed by rapid regression posteriorly during ventricular diastole. The velocity of the motion was 85 to 160 mm./sec. in normal subjects. In contrast, the records from 90 patients with mitral stenosis demonstrated a distinctive, abnormal pattern having a plateautype configuration with a velocity of posterior motion of only 2 to 35 mm./sec. The configuration of the curve changed toward normal after successful mitral valvulotomy but none of the 35 patients who were studied before and after surgery has developed a calculated postoperative velocity exceeding 70 mm./sec. Twelve patients with "pure" mitral regurgitation have had records similar to the normal, with velocities in or above the normal range. None of the 135 other patients studied, representing a variety of conditions, demonstrated a curve of the type found in mitral stenosis.