Ashman's Phenomenon (Ashman beat)

Ashman phenomenon (Ashman beat) occurs when a premature supraventricular beat occurs before the right bundle branch has recovered from its refractory period.

This results in the premature beat displaying a right bundle branch block pattern.

Frequently during premature atrial contractions; however, atrial fibrillation can express ashman phenomenon, as the R-R interval varies in this arrhythmia.

There is no clinical significance to this finding and no treatment is necessary, although some patients feel palpitations from the premature beat.