Event Title

A rare unidirectional, decremental left free wall accessory pathway causing an antidromic atrioventricular tachycardia: a left sided mahaim tachycardia

Location

Auditorium Pond Side

Start Date

26-2-2014 10:30 AM

Abstract

Antidromic atrioventricular reentrant tachycardia (aAVRT) is rare compared to orthodromic atrioventricular reentrant tachycardia (oAVRT). An aAVRT that is dependent on a unidirectional, accessory pathway (AP) is less common and one which is also decremental is even rarer. Decremental accessory pathways (which are atriofascicular and atrioventricular both grouped together as Mahaim tachycardias) are rare and seen on the right side predominantly, while on the left side they are extremely rare with only a couple of case reports in world literature. The preferred approach of ablation for such left sided tachycardias with anterograde conduction only is a retrograde transaortic approach; this facilitates mapping the earliest ventricular activation (at the AP insertion site) from the ventricular side during atrial pacing or tachycardia. This however, necessitates access to the arterial system with accompanying complications. We describe here, the case of a 32 year old man who presented with a wide complex tachycardia (WCT), which was treated initially as VT with intravenous lidocaine. The baseline ECG revealed a short PR interval of 110 ms but did not show preexcitation (WPW). Electophysiologic study (EPS) revealed a unidirectional left anterior accessory pathway which conducted anterograde only. AVRT was easily inducible at a cycle length of 290 - 310 msec. The diagnosis was confirmed with lab maneuvers to differentiate between WCT. The pathway was mapped to a 12 o’clock position on the mitral annulus and it showed decremental conduction like the AV node. Successful ablation was undertaken via the transseptal approach. Till last follow-up (over 28 months to ablation) there has been no recurrence.

Keywords: Left Mahaim tachycardia, decremental accessory pathway, WPW, WCT

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Feb 26th, 10:30 AM

A rare unidirectional, decremental left free wall accessory pathway causing an antidromic atrioventricular tachycardia: a left sided mahaim tachycardia

Auditorium Pond Side

Antidromic atrioventricular reentrant tachycardia (aAVRT) is rare compared to orthodromic atrioventricular reentrant tachycardia (oAVRT). An aAVRT that is dependent on a unidirectional, accessory pathway (AP) is less common and one which is also decremental is even rarer. Decremental accessory pathways (which are atriofascicular and atrioventricular both grouped together as Mahaim tachycardias) are rare and seen on the right side predominantly, while on the left side they are extremely rare with only a couple of case reports in world literature. The preferred approach of ablation for such left sided tachycardias with anterograde conduction only is a retrograde transaortic approach; this facilitates mapping the earliest ventricular activation (at the AP insertion site) from the ventricular side during atrial pacing or tachycardia. This however, necessitates access to the arterial system with accompanying complications. We describe here, the case of a 32 year old man who presented with a wide complex tachycardia (WCT), which was treated initially as VT with intravenous lidocaine. The baseline ECG revealed a short PR interval of 110 ms but did not show preexcitation (WPW). Electophysiologic study (EPS) revealed a unidirectional left anterior accessory pathway which conducted anterograde only. AVRT was easily inducible at a cycle length of 290 - 310 msec. The diagnosis was confirmed with lab maneuvers to differentiate between WCT. The pathway was mapped to a 12 o’clock position on the mitral annulus and it showed decremental conduction like the AV node. Successful ablation was undertaken via the transseptal approach. Till last follow-up (over 28 months to ablation) there has been no recurrence.

Keywords: Left Mahaim tachycardia, decremental accessory pathway, WPW, WCT