The 12-lead ECG in patients with Mahaim fibers

Comprehensive assessment of Mahaim accessory pathways' anatomic distribution

Objective

To present the authors’ experience of Mahaim-type accessory pathways (MAPs), focusing on anatomic localizations.

Methods

Data from consecutive patients who underwent electrophysiological study (EPS) for MAP ablation in two tertiary centres, between January 1998 and June 2020, were retrospectively analysed.

Results

Of the 55 included patients, 27 (49.1%) were male, and the overall mean age was 29.5 ± 11.6 years (range, 12–66 years). MAPs were ablated at the tricuspid annulus in 43 patients (78.2%), mitral annulus in four patients (7.3%), paraseptal region in three patients (5.5%), and right ventricle mid-apical region in five patients (9.1%). Among 49 patients who planned for ablation therapy, the success rate was 91.8% (45 patients).

Conclusion

MAPs were most often ablated at the lateral aspect of the tricuspid annuli, sometimes at other sides of the tricuspid and mitral annuli, and infrequently in the right ventricle. The M potential mapping technique is likely to be a useful target for ablation of MAPs.

An unusual preinduction arrhythmia resulting from the presence of a Mahaim fiber

A potentially life-threatening arrhythmia appeared on the preinduction electrocardiogram of an asymptomatic young woman prior to spine surgery. The patient was evaluated by electrophysiology and had a rare accessory pathway, a Mahaim Fiber.

Spontaneous automaticity arising from a successfully ablated Mahaim fiber

The authors describe a 22-year-old woman with regular and irregular arrhythmias exhibiting left bundle branch block (LBBB) morphology at various heart rates. An atriofascicular fiber was diagnosed as the underlying mechanism for the antidromic reciprocating tachycardia. In addition, spontaneous automaticity of the Mahaim fiber was present during electrophysiologic study. The accessory pathway was ablated successfully, targeting a Mahaim potential at the supero-anterior tricuspid valve annulus. Relatively slow automatic rhythms with identical LBBB morphology were recorded immediately after ablation, as well as during long-term follow-up in a more sporadic and subclinical form. Abnormal automaticity arising from the distal portions of the remnant pathway was considered to be the origin of the slow ventricular rhythms in this peculiar case.