An interesting cause of wide complex tachycardia: Ashman's phenomenon in atrial fibrillation.

BACKGROUND

Ashman's phenomenon is an aberrant intraventricular conduction abnormality that occurs in response to a change in QRS cycle length. In atrial fibrillation, Ashman's phenomenon will present as a long RR cycle followed by a short RR cycle, with the subsequent QRS complex manifesting a right bundle branch block morphology. This morphologic variation can create difficulty with electrocardiographic interpretation, and can alter management in patients with this dysrhythmia.

OBJECTIVES

This report presents a case, describes the Ashman's phenomenon in atrial fibrillation, and discusses interpretation of this electrocardiographic finding.

CASE REPORT: This is a 27-year-old woman who presented with palpitations and chest pain. The patient was symptomatic with a heart rate >200 beats/min and a wide complex tachycardia on electrocardiogram.

CONCLUSIONS

Ashman's phenomenon should be suspected in atrial fibrillation when there is a long cycle followed by a short cycle, with the subsequent QRS complex manifesting a right bundle branch block pattern. Emergency physician awareness of this phenomenon may improve diagnostic certainty and have an impact on dysrhythmia management.