Ashman phenomenon
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Ashman phenomenon, also known as Ashman beats, describes a particular type of wide QRS complex, often seen isolated that is typically seen in atrial fibrillation. It is more often misinterpreted as a premature ventricular complex. It is named for Richard Ashman (of New Orleans) (1890 –1969), after first being described by Gouaux and Ashman in 1947.


Presentation

Ashman beats are described as wide complex QRS complexes that follow a short R-R interval preceded by a long R-R interval. This short QRS complex typically has a
right bundle branch block A right bundle branch block (RBBB) is a heart block in the right bundle branch of the electrical conduction system. During a right bundle branch block, the right ventricle is not directly activated by impulses travelling through the right bu ...
morphology and represents an aberrantly conducted complex that originates above the
AV node The atrioventricular node or AV node electrically connects the heart's atria and ventricles to coordinate beating in the top of the heart; it is part of the electrical conduction system of the heart. The AV node lies at the lower back section of t ...
, rather than a complex that originates in either the right or left ventricle.


Cause

It occurs because the duration of the refractory period of the myocardium is proportional to the R-R interval of the preceding cycle. A short R-R interval is associated with a shorter duration of action potential and vice versa. A long R-R cycle will prolong the ensuing refractory period, and if a shorter cycle follows, the beat terminating the cycle is likely to be conducted aberrantly. Because the refractory period of the right bundle branch is longer than the left, the right bundle will still be in the refractory period when the supraventricular impulse reaches the His-Purkinje system, resulting in a complex with right bundle branch block morphology.


Prognosis

Clinically, it is often asymptomatic by itself and considered benign in nature.


See also

* Atrial fibrillation * Electrocardiogram


References


Further reading

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External links

{{Heart diseases Cardiac arrhythmia Medical signs Diseases named for discoverer