A Practical Criterion for the Rapid Detection of Single-Loop and Double-Loop Reentry Tachycardias

Pacemaker lead-related macroreentrant atrial tachycardia

Macroreentrant atrial circuits are frequently associated with scarring. Previous reports have shown the possible development of scar tissue that is adjacent to pacemaker (PM) leads. However, reports of PM lead-related reentrant tachycardia are scarce. We report the case of a 63-year-old woman who presented with macroreentrant atrial tachycardia (MAT), related to the atrial trajectory of an old single-lead ventricular PM, that was successfully treated with radiofrequency ablation after an conventional electrophysiological study ruled out isthmus-dependent atrial flutter and provided sufficient data to confirm this diagnosis.This report presents a case of MAT originating around the trajectory of a PM lead, probably because of scar tissue that developed adjacent to the lead. Experimental studies have already shown that interstitial atrial fibrosis may develop adjacent to a ventricular single-lead. This finding suggests that MAT develops in patients with this specific condition. Recognizing this condition is important for managing these arrhythmias and performing safe ablation with the preservation of PM lead integrity.

Right atrial dual-loop reentrant tachycardia after cardiac surgery: Prevalence, electrophysiological characteristics, and ablation outcomes

BACKGROUND

Right atrial (RA) dual-loop reentrant tachycardia has been described in patients who have undergone open heart surgery. However, the prevalence, electrophysiological (EP) substrate, and ablation outcomes have been poorly characterized.

OBJECTIVE

The purpose of this study was to investigate the prevalence, EP substrate, and ablation outcomes for RA dual-loop reentrant tachycardia after cardiac surgery.

METHODS

We identified all patients with atrial tachycardia (AT) after cardiac surgery. We compared EP findings and outcomes of those with RA dual-loop reentrant tachycardia to a control group of patients with RA macroreentrant arrhythmias in the setting of linear RA free-wall (FW) scar.

RESULTS

Of the 127 patients with 152 postsurgical ATs, 28 of the ATs (18.4%) had RA dual-loop reentry and 24 of 28 (85.7%) had tricuspid annular reentry combined with FW incisional reentry. An incision length >51.5 mm along the FW predicted the substrate for a second loop. In 22 of 23 patients (95.7%) with initial ablation in the cavotricuspid isthmus, a change in the interval between Halo_d to CS_p could be recorded, and 15 of 23 patients (65.2%) had coronary sinus activation pattern change. Complete success was achieved in 25 of 28 patients (89.3%) in the dual-loop reentry group and in 64 of 69 patients (92.8%) in the control group. After mean follow-up of 33.9 ± 24.2 months, 24 of 28 patients (85.7%) and 60 of 69 patients (86.95%) were free of arrhythmias after the initial procedure in the 2 groups, respectively.

CONCLUSION

The prevalence of RA dual-loop reentry is 18.4% of ATs with prior atriotomy scar. A long incision should alert physicians to the possibility of a second loop at the FW. Halo and coronary sinus activation patterns provide important clues to circuit transformation.

Usefulness of entrainment mapping using the activation sequence of the last captured excitation in complex dual-loop atrial tachycardia

BACKGROUND

Electroanatomical mapping is useful for locating the atrial reentrant circuit, but analysis of the dynamic relation of the reentrant circuit is sometimes difficult. This article describes three cases of complex dual-loop reentrant atrial tachycardia analyzed by entrainment mapping using not only the postpacing interval (PPI) but also the activation sequence of the last captured beats.

METHODS

Case 1 was dual-loop reentry consisting of the tricuspid annulus (TA) and a localized atrial reentry at the coronary sinus (CS) ostium with different exit sites to the right and the left atrium that was cured by catheter ablation at the CS ostium showing fractionated potential. Case 2 was dual-loop reentry around the TA and the superior trans-septal incision line. Case 3 was dual-loop reentry around the TA and longitudinal dissociation along the cavo-tricuspid isthmus.

RESULTS

In Cases 1 and 2, entrainment with a shorter pacing cycle length demonstrated antidromic penetration to the circuit and changed the activation sequence of the last captured beat depending on the anatomical relation of the reentrant circuit. In Cases 1-3 with dual-loop reentry, the excitation wavefront induced by stimulation entered one circuit after going around the other; thus, the penetration to the other reentry circuit became the second beat after the stimulus (one lap behind).

CONCLUSIONS

The PPI is obtained from the pacing site only, but the last captured beat could be obtained from all electrodes. It is advantageous to use the information from all available electrode recordings to determine the dynamic relation between complex dual-loop reentrant circuits.