Wide QRS supraventricular tachycardia due to coexisting Mahaim and Kent pathways

Multiple Ablation Targets in Children: Multiple Accessory Pathways and Coexistent Arrhythmia

The coexistence of different mechanisms of arrhythmia and multiple accessory pathways (MAPs) leading to multiple ablation targets is rarely seen in children, and data regarding these patients in the literature are limited. Herein, we aimed to evaluate patients who required multiple ablation applications, focusing on different targets during the procedures in children, and evaluating the characteristics of coexistent arrhythmia and MAPs, and the results of these procedures in children. Ablation procedures conducted between March 2009 and December 2018 were evaluated retrospectively, and patients with MAPs and/or coexistent arrhythmia who had undergone ablation procedures were included in the study. Among the 1210 patients who underwent ablation procedures, 52 patients (26 male, 26 female) were ablated for multiple targets. Of the 456 patients with APs, 21 had MAPs (4.6%) and of the 1210 patients who underwent ablation procedures, 31 patients had coexistent arrhythmia (2.5%). The patients had a mean age of 12.24 ± 3.4 (4-18) years and mean body weight of 45.17 ± 14.12 (17-74) kg. A total of 110 APs or foci were identified as quaternary in one patient, while it was triple in four patients. The procedures were unsuccessful in six targets of six patients. Although recurrence was observed in four patients, none were ablated for MAPs. Two complications were encountered, comprising ST segment depression that developed in one patient with Wolf-Parkinson-White syndrome, atrioventricular nodal re-entry tachycardia, and a temporary atrioventricular block during atrioventricular nodal re-entrant tachycardia ablation. The overall success rate according to the pathway/foci number was 94.5% (104/110), with a recurrence rate of 4.5% (5/110), and a complication rate of 1.8% (2/110). The patient success, recurrence, and complication rates were 88.4% (46/52), 7.6% (4/52), and 3.8% (2/52), respectively. In conclusion, the incidence of multiple arrhythmogenic foci and MAPs were not as low as expected in children. A structured and stepwise approach is mandatory for the diagnosis of the different mechanisms of tachycardia, even after successful ablation procedures. The success, recurrence, and complication rates were comparable with those of patients who had a solitary arrhythmogenic focus or solitary AP.

Coexistent Mahaim and Kent accessory connections: diagnostic and therapeutic implications

Six patients with coexistent Mahaim and Kent accessory connections are described. Two had left nodoventricular Mahaim connections, the first reported cases demonstrating these findings. In neither were the left-sided Mahaim connections components of a tachycardia and their presence was incidental. In two of four with nodoventricular connections, associated atrioventricular (AV) node conduction and coexistent posteroseptal accessory pathways were found. One of these had the unusual finding of a right-sided Mahaim connection arising from a "fast" AV node pathway. In only one patient did the tachycardia incorporate the Mahaim connection. In this patient, anterograde conduction during tachycardia occurred over a right nodoventricular connection whereas retrograde conduction occurred through a concealed right free wall Kent connection. Two patients had fasciculoventricular connections that were associated with either septal (one patient) or left free wall (one patient) Kent connections. The latter also had evidence of enhanced AV node conduction. This report is unique in that it describes in detail two patients with left nodoventricular connections (Mahaim) inserting in or near the left posterior fascicle. Combined Kent and Mahaim connections, present in the six patients, appear to occur in approximately 5% of patients with the Wolff-Parkinson-White syndrome. Precise identification of bypass connections critical for reentrant circuits is essential for intelligent application of treatment options.