title: [Diagnosis of an inactivable myocardial zone in the presence of left intraventricular block].
abstract: The electro-vectorcardiographic manifestations of uncomplicated and complicated proximal and peripheral blocks of the left conduction system are described. In the presence of an advanced degree LBBB, the septal activation which occurs with abnormal spreading, originates electromotive forces of greater duration and consequently more importance than normal ones. Peripheral left blocks provoke a segmental delay of left ventricle activation, producing an asynchronism of the electrical phenomenon between upper and lower regions of the ipsilateral ventricle. The coexistence of an inactivable anteroseptal zone with an advanced LBBB causes the phenomenon of "wave jumping" to begin in inferior posteroseptal regions. Therefore, the left external electrodes see the first ventricular activation fronts moving away and register Q waves. The presence of a transmural inactivable left parietal zone permits the corresponding external electrodes to record the morphology of the ipsilateral intraventricular complex. In certain cases, a LASB which shifts the first septal vector downward, can mask the existence of an inactivable anteroseptal or posteroinferior zone. A LPSB, which produces a strong III l vector oriented downward and to the left, can reduce the electrical manifestation of an inactivable posteroinferior zone.
authors.affiliation: Departamento de Electrocardiografía y Vectocardiografía, Instituto Nacional de Cardiología Ignacio Chávez, México, D.F.
authors.forename: A
authors.initials: A
authors.lastname: de Micheli
authors.forename: G A
authors.initials: GA
authors.lastname: Medrano
mesh_terms: D004562:Electrocardiography; D006327:Heart Block / Q000503:physiopathology*; D006801:Humans; D009203:Myocardial Infarction / Q000503:physiopathology*; D014672:Vectorcardiography
vernacular_title: El diagnóstico de zona inactivable miocárdica con bloqueo intraventricular izquierdo.