Ashman phenomenon
Also calledAshman beat · Ashman's phenomenon
Definition
An aberrantly conducted supraventricular beat, usually with right bundle branch block (RBBB) morphology, that ends a long-short RR sequence (a long cycle immediately followed by a short one). The refractory period of the right bundle branch lengthens after a long R-R interval, so an impulse that arrives soon after that long cycle can find the bundle still refractory and conduct aberrantly. It is most often seen in atrial fibrillation (irregular rhythms such as atrial flutter and atrial tachycardia also favor it), where it produces isolated wide beats or runs of wide beats that must be distinguished from ventricular ectopy such as nonsustained ventricular tachycardia.
Clinical noteGouaux and Ashman described it in 1947 in atrial fibrillation with aberration simulating ventricular tachycardia, so it is also called the Gouaux-Ashman phenomenon.
Sources
- Gouaux JL, Ashman R. Auricular fibrillation with aberration simulating ventricular paroxysmal tachycardia. Am Heart J. 1947;34(3):366-373. doi.org/10.1016/0002-8703(47)90487-0
- Chenevert M, Lewis RJ. Ashman's phenomenon: a source of nonsustained wide-complex tachycardia. J Emerg Med. 1992;10(2):179-183. doi.org/10.1016/0736-4679(92)90213-d
- Samesima N, God EG, Kruse JCL, et al. Brazilian Society of Cardiology guidelines on the analysis and issuance of electrocardiographic reports - 2022. Arq Bras Cardiol. 2022;119(4):638-680. doi.org/10.36660/abc.20220623
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.