Septal VA Time: How Short Is Too Short for Atrioventricular Re-Entrant Tachycardia?

BACKGROUND

A septal ventriculoatrial interval (VAI) of <70 ms often excludes atrioventricular reentrant tachycardia (AVRT) as a mechanism of supraventricular tachycardia (SVT).

CASE SUMMARY: A 49-year-old woman presented with symptomatic Wolff-Parkinson-White syndrome. Her electrophysiology study showed an AVRT with an unusually short VAI of 45 ms. The difference between the atrial signal interval during right ventricular pacing in sinus rhythm and the VAI during SVT was 30 ms. A functional left bundle branch block was induced, with a VAI of 85 ms (40 ms longer than the narrow complex SVT), suggesting conduction through an ipsilateral accessory pathway. Antegrade accessory pathway activation was mapped to the ostium of the middle cardiac vein and successfully ablated, resulting in the loss of antegrade pre-excitation.

DISCUSSION: This case report highlights the importance of considering AVRT when the VAI is <70 ms and establishes a new shortest VAI of 45 ms.