Ventricular septal defect: Correlation of electrocardiographic and hemodynamic findings in 60 proved cases

Abstract

The results of vectorial analysis of the conventional electrocardiograms are correlated with the hemodynamic factors in 60 patients with proved interventricular communications. Patients with a single ventricle or common atrioventricular canal were excluded from this study as were patients having ventricular septal defect associated with pulmonary stenosis or transposition of the great vessels. The exact anatomic findings and hemodynamic data were examined to investigate possible correlation with data shown by the electrocardiogram. Of the 56 patients in whom the vectorial analysis of the QRS complexes could be obtained from the three standard and unipolar augmented extremity leads, it was noted that the loop in the frontal plane rotated clockwise in 33 and counterclockwise in 14; in nine patients (15 per cent) it was similar to the type described as characteristic of patients with abnormalities of the atrioventricular canal. Precise quantitative correlation could not be established between the electrocardiographic criteria used in this study and data for pulmonary arterial pressure or for pulmonary vascular resistance, but a relationship was detected between the type of overloading of the right ventricle and the configuration of QRS complexes in lead V 1, as well as other significant electrocardiographic characteristics. Right ventricular diastolic overloading type complexes in lead V 1, frequently associated with QRS loops rotating in a clockwise direction in the frontal plane with mean axes for QRS complexes similar to those of patients having defects of the atrial septum, were found in 20 patients (group 1) in the series. In 17 of these an anatomic basis was found to explain diastolic overloading of the right ventricle. Configuration of QRS complexes in lead V 1 and position of the mean axes of QRS complexes similar to those of patients with patent ductus arteriosus, with electrocardiographic findings suggestive of overloading of the left ventricle frequently associated with QRS loops rotating in counterclockwise direction in the frontal plane, were found in 10 patients (group 2) in this series. In all cases of this group, the defects were located in the outflow tract of the right ventricle; thus the right ventricle itself was minimally involved in the functional derangement since it did not participate in the recirculation of blood through the pulmonary circuit. In this situation, as in the case of patients with patent ductus arteriosus, the right ventricle develops systolic overloading only as a result of elevated pulmonary vascular resistance. Electrocardiographic characteristics intermediate between those noted for group 1 and group 2 were found in 30 patients (group 3). The location of the defect in various parts of the ventricular septum appears to be an important factor in determining the type of overloading to which the right ventricle is subjected. The best criteria suggesting overloading of the right ventricle were increased magnitude of the R wave in lead aVR (76 per cent), prolonged intrinsicoid deflection (75 per cent), and abnormal R S or R S + S ratio in lead V 1 (78 percent). Even though QRS complexes of high potential in left precordial leads were found in 36 cases of this series, a prolonged intrinsicoid deflection in the left precordial leads was a better criterion (78 per cent) suggesting “hypertrophy” of the left ventricle. The R wave in lead Y 6 was equal to or higher than 21 mm in 60 per cent of the cases. In 60 per cent of the patients with electrocardiographic data suggesting hypertrophy of the left ventricle, a T wave of the type called “diastolic overloading” was found in the left precordial leads and other leads representing the potential of the left ventricle.