Evidence for an incomplete mitral isthmus block after failed ablation of a left postero-inferior concealed accessory pathway

Abstract

We report the case of a young woman in whom previous ablation of a concealed left-sided accessory pathway (AP) created an iatrogenic mitral block. The mitral block was responsible for a split retrograde atrial activation pattern during orthodromic atrioventricular re-entrant tachycardia (AVRT). The differential diagnoses are discussed. The AP was ablated at the site with the shortest interval between the ventricular signal and the earliest component of the retrograde atrial activation. Meticulous mapping is paramount during AVRT with an unusual retrograde atrial activation pattern.

Intraatrial conduction block in the right posteroseptal region after failed accessory pathway ablation—Importance of delineation of three-dimensional pathway geometry

“…Even though local conduction delay does not occur frequently after RF ablation, there are reports of iatrogenic block in patients who underwent ablation for left-sided APs. A report by Bortone and colleagues 6 described previous ablation for concealed left-sided AP creating iatrogenic block responsible for a split retrograde atrial activation pattern during orthodromic AVRT. The AP was ablated at the site with the shortest interval between the ventricular signal and the earliest component of the retrograde atrial activation, as was done in our patient during the second procedure.…”