What is complete heart block? Cardiology Basics

What is complete heart block? Cardiology Basics
When natural pacemaker impulses from the sinoatrial node fails to reach the ventricles and activate them, it is known as complete heart block. The block could be at the level of the atrioventricular (AV) node or below that.
Sinus node is a subepicardial structure located in the upper part of right atrium near the orifice of the superior vena cava. Signals from sinus node travel to the AV node through three internodal pathways. They are Wenckebach, Thorel and Bachmann bundles. Bachmann bundle gives a branch to the left atrium also.
AV node is located near the atrioventricular junction in the lower part of right atrium. It is a subendocardial structure, located at the apex of the triangle of Koch. Triangle of Koch is bounded by the tendon of Todaro, coronary sinus orifice and septal leaflet of tricuspid valve. AV node is a slow conducting tissue which causes the predominant portion of the physiological AV delay.
Bundle of His originates from the lower part of the compact AV node and traverses the AV junction. Normally atria and ventricles are electrically isolated and conduction occurs only through the bundle of His. Bundle of His is fast conducting specialised conduction tissue.
Bundle of His divides into right and left bundle branches which take signals to the corresponding ventricles. Left bundle branch has an anterior and posterior division, meant for the corresponding regions of the left ventricle.
If the signals conducted do...

Source: Cardiophile MD - October 17, 2022 Category: Cardiology Authors: Johnson Francis Tags: General Cardiology Source Type: blogs