What is the normal cardiac conduction relevant to pediatric right bundle branch block?

Updated: Jul 26, 2018
  • Author: Glenn T Wetzel, MD, PhD; Chief Editor: Syamasundar Rao Patnana, MD  more...
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In normal cardiac conduction, electrical excitation of the heart proceeds in a sequential manner from the atria to the ventricles and is demonstrated on the surface ECG (see the image below).

This image depicts the electrophysiologic sequence This image depicts the electrophysiologic sequence of events that occur in normal cardiac conduction. AV = atrioventricular.

The electrical impulse is generated in the sinus node and proceeds along proposed internodal conduction pathways to reach the AV node. As the impulse conducts through the AV node, conduction slows, allowing time for atrial contraction to occur before the ventricle is activated (PR segment). After the impulse passes through the compact AV node, it is rapidly conducted through the crux of the heart to the ventricles by means of the bundle of His (penetrating bundle) to the branching bundle, the bundle branches, the distal Purkinje fibers, and finally the ventricular myocardial cells (narrow QRS complex). When depolarization is complete, the ventricle repolarizes in preparation for conducting another impulse.

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