Transient left septal fascicular block and left anterior fascicular block as a consequence of proximal subocclusion of the left anterior descending coronary artery

Abstract

The association of left anterior fascicular block (LAFB) with left septal fascicular block (LSFB) characterizes a left bifascicular block subtype rarely described in the literature, probably due to the fact that most researchers are not aware of the existence of the left septal fascicle. We describe a case with this transient intraventricular dromotropic disturbance due to left anterior descending coronary artery subocclusion.

Variant Angina with Spontaneously Documented Ischemia- and Tachycardia-induced "Lambda" Waves

“…In contrast, the existence of conduction defects of the LSF remains controversial. Pérez-Riera et al reported several cases of transient PAF thought to be caused by LSFB in the setting of proximal LAD disease and have stated that the characteristic ECG feature of LSFB is PAF on the horizontal plane (21,22). These ECG findings should be distinguished from other conditions that also produce PAF, such as right ventricular enlargement, lateral myocardial infarction, right bundle branch block, Wolff-Parkinson-White syndrome, hypertrophic cardiomyopathy, and Chagas cardiomyopathy in Latin America.…”

Forças Anteriores Proeminentes do QRS Durante Suboclusão Transitória do Tronco da Coronária Esquerda

“…Vários manuscritos sucessivos do nosso grupo e de outros mostraram que uma grande proporção de casos com LSFB, manifestado por forças anteriores proeminentes do QRS, é causada por obstrução proximal crítica da DAE antes de seu primeiro ramo perfurante septal. [6][7][8][9] Como a DAE é uma continuação do TCE, uma obstrução significativa do TCE pode levar à isquemia na porção média e no território apical do ventrículo esquerdo, onde fica o fascículo septal esquerdo, causando a LSFB.…”

The tetrafascicular nature of the intraventricular conduction system

“…Hence, the patient had a left bifascicular block consisting of LAFB + LSFB. [1][2][3][4][5] We have presented several cases indicating that LSFB is not necessarily a rare ECG finding. Although well known from textbooks and other sources, isolated left posterior fascicular block (LPFB) without right bundle branch block (RBBB) is a very rare finding.…”

“…LSFB has been described in the following scenarios [1][2][3][4][5] : proximal obstruction of the left anterior descending (LAD) coronary artery with or without acute coronary syndrome and with the Wellens syndrome 6 ; exercise-induced during the treadmill test, 7 chronic Chagasic myocarditis 8 ; Kearns-Sayre syndrome 9 ; self-expandable percutaneous transcatheter aortic valve implantation 1 ; diabetes 10 ; and aberrant conduction in healthy individuals. 11 As data on LSFB is missing, so far there is no epidemiological data to establish the exact prevalence of all four main blocks of the left His system.…”