Angular displacement of the papillary muscles during the cardiac cycle.

Abstract

Left ventricular rotation about the longitudinal axis of the heart was qualitatively described but difficult to quantitate. Cross-sectional echocardiography offers a simple noninvasive method for determining both the presence and degree of left ventricular rotation. Normals and patients with various forms of heart disease were studied for angular displacement of the papillary muscles during the cardiac cycle. Assuming that the papillary muscles represent fixed internal reference points, angular displacement of these points represents left ventricular rotation about the longitudinal axis. Short-axis cross-sectional echocardiograms were recorded in 100 patients: 34 normals, 16 patients with secundum atrial septal defect and 50 patients with various forms of valvular, congenital and ischemic heart disease. Angular displacement of the papillary muscles was determined by measuring the angle subtended between a line drawn parallel to the chest wall and a 2nd line drawn through the tips of the papillary muscles. The degree of angular displacement of the papillary muscles was derived by subtracting the diastolic angle from the systolic angle. This value was interpreted to represent the degree of left ventricular rotation about the longitudinal axis during the cardiac cycle. The normal group had a minimal degree of counterclockwise left ventricular rotation (mean 3.0.degree.; range 0.6.degree.). Exaggerated counterclockwise left ventricular rotation was seen in patients with secundum atrial septal defect (mean 17.2.degree.; range 9-29.degree.; P < 0.001). Of these patients 8 were studied after surgical closure of the defect and the pattern of left ventricular rotation was not significantly different from that in normals (mean 3.3.degree.; range 2-5.degree.). The 3rd group of patients who had various forms of heart disease, including right ventricular volume and pressure overload, had minimal left ventricular rotation (mean 3.2.degree.; range 0-7.degree.). Apparently minimal counterclockwise left ventricular rotation occurs in normals and patients with heart disease. 0.6). Exaggerated left ventricular rotation is characteristically seen inpatients with secundum atrial septal defect and is abolished after surgical closure of the defect.