Resumo

MICHELI, Alfredo de; MEDRANO, Gustavo A  e  ARANDA, Alberto. On the polyfascicular blocks with and without dead myocardium. Arch. Cardiol. Méx. [online]. 2002, vol.72, n.3, pp.240-248. ISSN 1665-1731.

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 septal 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 V_4. 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, that 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.

Palavras-chave : Left bifascicular block; Trifascicular block; Left bifascicular block with dead myocardium; Trifascicular block with dead myocardium.

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