[Electro-vectorcardiographic aspects of diastolic and mixed overloads of the right ventricle].

We studied 400 cases of isolated atrial septal defect without severe pulmonary hypertension, in which the diagnosis was established by the hemodynamic data and it was proven by surgical findings in 257 instances. High fidelity unipolar thoracic and intracardiac records, as well as vectorcardiographic curves in three planes, were obtained. Different types of right ventricular conduction disturbances, which were present in all cases, as well as certain electro-vectorcardiographic aspects related to ventricular depolarization and repolarization, were analyzed. Mean angles of the resulting vectors at 60 msc of the ventricular activation, were determined relating to the types of block. The following points should be emphasized: Besides the right proximal blocks, which are more frequent, right distal ones can also be diagnosed by the presence of slurred R wave and delayed onset of the intrinsicoid deflection in only some right leads. The monofascicular and parietal right blocks are observed when the diastolic overload of the ipsilateral ventricle is low. The activation time of the anterior inferior right septal mass generally permits an objective classification of the degree of a right proximal block. The prolonged Q-Tc interval only in right leads, seems to be a function of the magnitude of the right ventricular diastolic overload.