THE LEFT PARASTERNAL IMPULSE

Abstract

The left parasternal impulse has been recorded, using an instrument which measures total displacement of the chest wall, in 20 normal subjects and 71 patients with congenital or acquired disease of the right ventricle. The detailed pattern of normal and abnormal impulses has been described. There were 3 main groups the normal, the overacting, and the sustained. In most normal subjects there was an outward movement of the chest in the left parasternal area during early systole, followed by retraction in late systole; in some an inward movement only occurred. An overacting impulse of unusually large amplitude but normal contour was seen in children and in sternal depression. Healthy hearts, therefore, showed either a normal or overacting left parasternal impulse. Most patients with an atrial septal defect without pulmonary hypertension showed an overacting impulse reflecting the augmented right ventricular stroke output. Four-fifths of the patients with marked right ventricular hypertrophy from right ventricular hypertension had a sustained impulse lasting up to the time of the second heart sound or beyond; 1 /5 had an overacting or normal impulse. A bifid sustained impulse was noted in some cases of ventricular septal defect with pulmonary hypertension. The presence of a sustained left parasternal impulse was found to be a reliable sign of hypertrophy of the right ventricle, except in rare cases where an enlarged left ventricle underlay this area of the precordium. An atrial beat at the left sternal edge, accompanying atrial systole, was seen more often in right ventricular hypertrophy with associated right atrial hypertrophy than in health. A giant atrial beat, dwarfing the succeeding ventricular impulse, appreciated by the hand as a double impulse, was found to be characteristic of one form of cardiomyopathy with diminished compliance of the ventricles.