THE LATE INTRACARDIAC R WAVE AND THE PRAeCORDIAL PATTERN OF RIGHT VENTRICULAR HYPERTROPHY

There is no generally accepted explanation of the mainly positive initial deflections seen in the right prxecordial electrocardiogram in right ventricular hypertrophy.McGregor (1950) found in Fallot's tetralogy that whereas the initial deflections in right precordial leads were of the rsR' form or rsR's, direct leads from the right ventricular epicardium were rS in type.He suggested that these mainly positive deflections from the right side of the chest arose from the left ventricle as a result of rotation, or from an area near the right atrio-ventricular groove.Carouso et al. (1952) obtained tall, late positive deflections (rsR') in direct leads from the epicardium on either side of the right atrio-ventricular groove in five patients with right ventricular hypertrophy.Similar complexes from the same area in normal animals had already been reported (Groedel et al., 1947).Several workers interested in human intracardiac electrography have noted that although the ventriculogram obtained from the cavities and great vessels of the right heart is usually mainly negative, sometimes a late, mainly positive deflection is obtained.Kossman et al. (1950) found that in normal patients these late intracardiac R waves (qR or rsR') were sometimes recorded from the right ventricle, sometimes from the lower part of the right atrium, or from the pulmonary artery just above the pulmonary valve.They found that deflections of this type in the pulmonary artery or right atrium were reversed on movement of the catheter into the right ventricle, and they argued that this implied that the deflections were caused by depolarization of muscle near both the pulmonary and tricuspid orifices, for example, the crista supraventricularis.They suggested that hypertrophy of this muscle might be responsible for the late positive deflections obtained from right prncordial leads in right ventricular hypertrophy.In patients with right ventricular hypertrophy Kroop et al. (1951) found this rsR' (or rsR's) pattern just above the pulmonary valve, and in the right atrium; they did not obtain it from the right ventricle.It was not recorded from the pulmonary artery in normal hearts.They, too, pointed out its similarity to the pattern found in leads VI and aVR in right ventricular hypertrophy, and suggested that it might be caused by depolarization of the right ventricular surface.Sodi-Pallares et al. (1951), discussing the late R sometimes recorded from within the right atrium, suggested that it arose from the late activation of muscle high in the septum, and they stated that in right ventricular hypertrophy these right atrial patterns were like those recorded from the right prxcordium.This paper records the incidence of the late intracardiac R wave in 50 patients, and correlates its occurrence and amplitude with right ventricular pressure and form of ventricular complex in the conventional electrocardiographic leads VI and VR. MATERIAL AND METHODSDuring the cardiac catheterization of 50 cases of congenital and acquired heart disease simultaneous records were made of electrocardiographic leads VR and VI, the intracardiac electrogram, 78 on November 22, 2023 by guest.