Electro-vectorcardiographic demonstration of bifascicular block associated with ventricular preexcitation

The tetrafascicular nature of the intraventricular conduction system

The existence of a tetrafascicular intraventricular conduction system remains debatable. A consensus statement ended up with some discrepancies and, despite agreeing on the possible existence of an anatomical left septal fascicle, the electrocardiographic and vectorcardiographic characteristics of left septal fascicular block (LSFB) were not universally accepted. The most important criteria requested to confirm the existence of LSFB is its intermittent nature. So far, our group has published cases of transient ischemia-induced LSFB and phase 4 or bradycardia-dependent LSFB. Finally, anatomical, anatomopathological, histological, histopathological, electrocardiographic, vectorcardiographic, body surface potential mapping, and electrophysiology studies support the fact that the left bundle branch divides into three fascicles or a "fan-like interconnected network."

Transient left septal fascicular block in a patient with stable effort angina and critical proximal obstruction of left anterior descending coronary artery

Several publications from our group and others have shown that a main cause of middle fiber block or left septal fascicular block of the left bundle of His is proximal obstruction of the left anterior descending coronary artery, before its first septal perforator branch, since this fascicle is the only one of the three fascicles irrigated exclusively by this artery. We present a case in which the phenomenon occurred transiently, causing prominent anterior QRS forces, confirmed by coronary angiography.

Electro-vectorcardiographic demonstration of bifascicular block associated with ventricular preexcitation

Down syndrome occurs more frequently in the offsprings of older pregnant women and may be associated with atrioventricular septal defect. This refers to a broad spectrum of malformations characterized by a deficiency of the atrioventricular septum and abnormalities of the atrioventricular valves caused by an abnormal fusion of the superior and inferior endocardial cushions with the midportion of the atrial septum and the muscular portion of the ventricular septum.