Ashman Phenomenon – mechanism

Ashman Phenomenon


Ashman Phenomenon is typically


[A] RBBB morphology
[B] LBBB morphology
[C] Long pause after ashort cycle
[D] Idioventricular rhythm



What is the mechanism of Ashman Phenomenon?

what happens in Ashman Phenomena?

  1. Long cycle R-R interval followed by – short cycle R-R interval – The short cycle is terminated with a abberrant QRS complex.
  2. Long cyle – has long refractory period.
  3. Short cycle – When short cycle follows – the refractory period of previous beat is not completely over
  4. Refractory period of the right bundle branch is longer than the left
  5. Right bundle will still be in the refractory period when the supraventricular impulse reaches the His-Purkinje system
  6. This results in a complex with right bundle branch block morphology

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.

Ashman Phenomenon

AF with RVR-Ashmans phenomenon-RBBB aberrancy

Jer5150, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

Long cycle followed by short cycle and short cycle terminated by aberrant QRS complex

End of short cycle R wave is notched – RBBB morphology – called as Ashman Phenomenon

  • Ashman Phenomenon
  • Ashman phenomenon describes an aberrant ventricular conduction
  • Usually of RBBB morphology
  • Which follows a short R-R interval
  • Preceding relatively prolonged R-R interval