Abstract
10 cases of tetralogy of Fallot were studied at the time of cardiac surgery by placing an exploring electrode (an insulated wire tipped by a moist cotton swab 0.5 inch in diam.) on the exposed pericardium. The right ventricular surface transmitted an rS pattern, which is similar to that derived from the immediately overlying left precordium. Similarly, a qR pattern was recorded from the left ventricular surface. These findings are considered due to rotation of the heart.