[Intraventricular conduction disorders in experimental right septo-parietal infarction].

In 16 mongrel dog hearts the electrocardiographic (ECG) and vectocardiographic (VCG) alterations provoked by chemical necrosis within the anterior free right ventricular wall and anterior portion of the interventricular septum were studied. The necrosis was associated to isolated right bundle branch block (RBBB), or the latter associated to left anterior subdivisional block (LASB). The abnormal Q waves from the epicardial right ventricular wall were transmitted to the right thoracic leads in 25% of the cases with isolated RBBB instead of 43% in its absence. However the addition of a LASB or LASB+ left posterior subdivisional block (LPSB) increased its presence to 83.3%. Nevertheless, rSRS' with slurred first S wave were observed on the right thoracic surface as well as on the right epicardium and ventricular chamber. Those morphologies have a very significant value for right ventricular necrosis in the presence of RBBB, increasing the percentage of positive diagnoses. Anteroseptal necrosis was recognized more frequently (93.7%) in the epicardial unipolars than in thoracic leads (75%), but positive diagnosis increases to 93.3 in the latter when one or two left subdivisional blocks were provoked. Vectocardiographic loops showed an earlier backward displacement of centrifugal limbs in the horizontal and sagittal planes not very different of that observed in septal necrosis for humans. These signs were more frequently seen with RBBB than without it, and even more oftenly, when a left distal block was associated. Nevertheless, ECG right thoracic leads alterations are more convincing and must be done and analysed in order to confirm the diagnosis.