A.: The spatial QRS loop in right ventricular hypertrophy with special reference to the initial component. Circulation 7: 573

Spatial vectorcardiograms were recorded from 18 subjects with normal electrocardiograms and from 14 subjects with electrocardiograms indicative of right ventricular hypertrophy. In the latter group there was a significant incidence of deviation of the initial portion of the QRS loop from the normal direction of inscription, suggesting that activation of the interventricular septum often proceeds in an abnormal manner in right ventricular hypertrophy. A statistically significant dif-ference in the direction of rotation of the entire QRS loop in the transverse and sagittal planes was noted in the two groups. The relationship between the direction of inscription of the QRS loop in the transverse plane and the timing of the intrinsicoid deflections of precordial leads is discussed. IN an earlier paper it was demonstrated that the normal rS * pattern in the elec-trocardiogram of the right ventricular cavity is sometimes replaced by a QS pattern in right ventricular hypertrophy. ' This con-dition was shown to obtain in five of seven cases of right ventricular hypertrophy who had a qR pattern in electrocardiographic V leads fromlithe right precordium.1 ' 2 It was believed that further information concerning this prob-lem might be obtained from a study of the spatial QRS loop by means of the vectorcar-diograph, paying special attention to the initial portion of the QRS loop. MATERIAL Eighteen convalescent patients with normal scalar electrocardiograms were studied from the medical wards of the Cincinnati General Hospital. These are listed in table 1. Fourteen patients with right ven-tricular hypertrophy were studied from the medical wards and the Out-Patient Department of the Cin-cinnati General Hospital. These subjects and their diagnoses are given in table 2. The criteria of selec-tion of the latter were: (1) the presence of a clinical condition usually associated with right ventricula