[Non-complicated and complicated polyfascicular blocks].
Septal necrosis + Peripheral blocks. Because of an extensive septal necrosis, the manifestation of the initial ventricular activation forces decreases in the precordial leads. With left bifascicular block, first ventricular activation forces become evident, and the electrical signs of a sepatal necrosis are concealed. In the presence of a trifascicular block, the manifestation of the first ventricular electromotive forces diminishes again and the electrical signs of septal necrosis become evident once more. Small Q waves are present in leads V1 to V4. Extensive anterior necrosis + Peripheral blocks. Such a necrosis is manifested by QS complexes from V2 to V6. An associated left bifascicular block reduces the electrical manifestation of dead tissue: QS complexes persist only in V3 and V4. A trifascicular block determines the presence of QS complexes from V2 to V5. Posteroinferior necrosis + Peripheral blocks. Electromotive forces of the ventricular activation shift upward, due to a posteroinferior necrosis. QS or QR complexes are recorded in leads a VF, II, and III. A left bifascicular block displaces the main electromotive forces downward, posteriorly and to the left, due to a delay of the posteroinferior activation. QRS complexes become positive and wider in all leads, the reflect the potential variations of the inferior portions of the left ventricle: aVF, II, and III, sometimes V5 and V6. The electrical signs of necrosis are reduced or abolished. With a trifascicular block, wide and slurred QS complexes appear in aVF, II, III, and sometimes in V5 and V6 too.
de Micheli
Alfredo
A
Instituto Nacional de Cardiología Ignacio Chávez, INCICH, Juan Badiano No. 1, Col. Sección XVI, Tlalpan, 14080 México, D.F.
Medrano
Gustavo A
GA
Aranda
Alberto
A
D002037:Bundle-Branch Block / Q000150:complications* / Q000503:physiopathology*; D006801:Humans