Postmitral Valve Replacement Biatrial, Septal Macroreentrant Atrial Tachycardia Developing After Perimitral Flutter Ablation

Abstract

A typical macroreentrant atrial tachycardias are frequently encountered in patients after cardiac surgery, correction of congenital heart disease, or atrial fibrillation ablation. Ablation of one circuit can produce an abrupt change in atrial activation sequence giving rise to another macroreentrant circuit. In this report, we present a unique case of a biatrial septal macroreentrant atrial tachycardia, which developed after perimitral flutter ablation in a patient with mitral valve replacement. Editor's Perspective see p 175A 59-year-old man with a mitral valve replacement (bioprosthesis) in 1983 for a rheumatic mitral stenosis and a rereplacement in 1999 (right-sided approach with a vertical incision of the interatrial septum) with a mechanical prosthesis attributable to the degeneration of the former prosthesis was referred for the ablation of a sustained atrial tachycardia with a stable cycle length of 260 ms. The echocardiogram demonstrated a left ventricular ejection fraction of 45% to 50%, a moderately dilated right atrium (RA) as well as left atrium (LA) without signs of a prosthetic malfunction. The baseline surface 12-lead ECG showed an atypical atrial flutter with a regular, monomorphic atrial activity and an irregular atrioventricular conduction ( Figure 1A). With broad positive flutter waves in unipolar lead V1 and inferior limb leads II, III and avF but negative flutter waves in limb leads I and avL, the ECG morphology suggested LA localization. Any significant 12-lead isoelectric interval was absent. Endocardial activation mapping with a quadripolar catheter in the RA and a steerable octapolar catheter in the coronary sinus (CS; Bard Medical, Covington, GA) demonstrated a distal to proximal activation sequence in the CS with a baseline cycle length of 260 ms, suggestive of a lateral to septal activation of the LA posterior wall ( Figure 1B). An irrigated tip ablation catheter (Navistar Thermocool, Biosense Webster, Diamond Bar) was advanced into the LA via a transseptal puncture. Return cycle mapping at a pacing cycle length of 240 ms demonstrated a postpacing interval (PPI) of 430 ms in the RA free wall, 320 ms in the posterior LA wall, 290 ms in the LA roof, and finally 260 ms in the distal CS, allowing the confirmation of an LA localization of the macroreentrant tachycardia ( Figure 1C). Subsequent electroanatomical mapping (CARTO XP, Biosense Webster, Diamond Bar) of the LA during tachycardia revealed a clockwise perimitral flutter, but with a relatively narrow isthmus (12 mm) in the anterior LA wall, bounded above (and anteriorly to the RSPV ostium) as well as below (to the anterior mitral annulus) by a line of block, consistent with a surgical approach scar for the mitral valve replacement surgery ( Figure 1D). Ablation of this isthmus was started targeting single, healthy voltage potentials choosing this more anteriorly located narrow isthmus over the classic mitral isthmus. The tachycardia slowed progressively (CL 330 ms) during radiofrequency energy delivery, and a pause followed by an ab...

Biatrial Tachycardia Following Linear Anterior Wall Ablation for the Perimitral Reentry: Incidence and Electrophysiological Evaluations

“…A type of a bi‐AT after anterior linear ablation for PMF has been recently described in a patient after mitral valve surgery; this bi‐AT has been localized to the FO . The authors emphasized the importance of RA evaluation in AF patients for correct diagnosis and AT ablation.…”

Editor’s Perspective: The Isthmus of Uncertainty

“…Circulation Arrhythmia & Electrophysiology readers and students of electrophysiology will indeed appreciate the approach and elucidation of the steps to successfully ablate even complex flutters occurring in postsurgical atria presented in this issue by Namdar et al 1 The student should become familiar with what exactly is meant by the terms early site, exit, boundary, and isthmus.…”

“…In the patient discussed by Namdar et al, 1 when entrainment was attempted from the right atrial freewall, the postpacing interval (PPI) was almost twice the cycle length of the tachycardia. Although this is possible purely from combined distance and temporal delay in diseased hearts, the operator should suspect an intermediary area of block and forced conduction through a slow zone.…”

“…Namdar et al, 1 in this installment of Teaching Rounds in Cardiac Electrophysiology, present and explain insightful findings from a patient with a complex macro-reentrant circuit encountered after prior cardiac surgery. They take us through a step-by-step approach and their thought process in identifying the eventual curative ablation target.…”

Dual‐Loop Bi‐Atrial Macroreentrant Atrial Tachycardia in a Patient With Modified Cox Maze IV: Where Is the Initial Ablation Target?

“…Bi‐atrial AT has been reported in patients after mitral valve plasty or ablation of the anterior LA line for PMAT . Interatrial conduction normally occurs via anatomically distinct connections such as the Bachmann bundle, around the fossa ovalis, and rarely in the CS .…”