A change in the length of the QRS cycle leads to irregularity in ventricle conduction. This was first reported by Ashman and thus, termed the Ashman phenomenon. A short cycle generating an aberrant QRS complex followed by a relatively long cycle; irregular coupling of QRS complexes; bundle branch block-pattern aberrancy with a normal orientation of the initial QRS vector; and lack of a fully compensatory pause are the four diagnostic features of the Ashman phenomenon, according to the Fisch criteria.
Nocturnal episodes of wide QRS complex tachycardia during vagally mediated PAF resulting from Gouaux-Ashman's phenomenon is reported for the first time through this case. Wide QRS complex of the tachycardia episodes is a diagnostic feature of ventricular tachycardia as well. Hence, to prevent misdiagnosis and improve the therapeutic management of arrhythmic episodes, it is of utmost importance for physicians to recognize the difference between the Ashman phenomenon and ventricular tachycardia.
A 38-year-old male patient consulted for nocturnal palpitations. Preliminary examination detected no neurological abnormalities, lower limb oedema, murmurs, rubs, or gallops in cardiac auscultations. Chest x-rays and laboratory blood tests analysis produced normal results. HR was noted to be 72bpm.
Wide QRS complex tachycardia with the coexistence of nocturnal episodes of paroxysmal atrial fibrillation (PAF) was revealed in a 24-hour ambulatory Holter ECG. A long cycle length of 408ms was followed by the first wide QRS complex with a cycle length of 312ms. R-R Interval preceding the long cycle measured 288ms. Thus, short-long-short cycle length preceding aberrancy generating the wide QRS complex tachycardia was clearly depicted. The fulfilment of Fisch criteria confirmed the Ashman phenomenon.
The patient was prescribed a daily dose of 600 mg propafenone.
Name of contributor:
Orlando Robert Sequeira, Osmar Antonio Centurion, and Luis M Mino
In Atrial Fibrillation, when a short cycle follows a long cycle with subsequent wide QRS complex beats, aberrancy due to Gouaux-Ashman's phenomenon can be suspected in cases of wide QRS complex tachycardia. It is important that the physicians are made aware of this phenomenon to prevent misdiagnosis and improve treatment.