Cardiac aberrancy is a type of disruption in the shape of the electrocardiogram signal, representing abnormal activation of the ventricular heart muscle via the

electrical conduction system of the heart The cardiac conduction system (CCS, also called the electrical conduction system of the heart) transmits the Cardiac action potential, signals generated by the sinoatrial node – the heart's Cardiac pacemaker, pacemaker, to cause the heart musc ...

. Normal activation utilizes the

bundle of His The bundle of His (BH) or His bundle (HB) ( "hiss"Medical Terminology for Health Professions, Spiral bound Version'. Cengage Learning; 2016. . pp. 129–.) is a collection of heart muscle cells specialized for electrical conduction. As part of ...

and

Purkinje fibers The Purkinje fibers, named for Jan Evangelista Purkyně, ( ; ; Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, just beneath the endocardium in a space called the subendocardium. The Purki ...

to produce a narrow (QRS) electrical signal. Aberration occurs when the electrical activation of the heart, which is caused by a series of

action potentials An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific cell rapidly rises and falls. ...

, is conducting improperly which can result in temporary changes in the morphology that looks like: * Left bundle branch block ** Left anterior fascicular block ** Left posterior fascicular block *

Right bundle branch block A right bundle branch block (RBBB) is a heart block in the Bundle branches#Structure, right bundle branch of the Electrical conduction system of the heart, electrical conduction system. During a right bundle branch block, the right ventricle (h ...

This is in contrast to a permanent dysfunction of the electrical pathways that produces wide QRS complexes in one of the above patterns or combinations of patterns (ie,

bifascicular block Bifascicular block is characterized by right bundle branch block with left anterior fascicular block, or right bundle branch block with left posterior fascicular block on electrocardiography. Complete heart block could be the cause of syncope ...

). In the context of

atrial fibrillation Atrial fibrillation (AF, AFib or A-fib) is an Heart arrhythmia, abnormal heart rhythm (arrhythmia) characterized by fibrillation, rapid and irregular beating of the Atrium (heart), atrial chambers of the heart. It often begins as short periods ...

, the Ashman phenomenon is a form of aberrancy. Aberrancy is due to prematurity in which part of the conduction system is still

refractory In materials science, a refractory (or refractory material) is a material that is resistant to decomposition by heat or chemical attack and that retains its strength and rigidity at high temperatures. They are inorganic, non-metallic compound ...

and cannot conduct the premature depolarization. This effect can sometimes be seen in the setting of a faster heart rate (

tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal ...

) and so is termed "rate-related aberrancy." After the first aberrant complex, subsequent complexes may be wide due to concealed conduction rather than aberrancy.

See also