Mahaim pathway potential revealed by high-resolution three-dimensional mapping
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Case Reports Herzschr Elektrophys https://doi.org/10.1007/s00399-020-00721-8 Received: 29 July 2020 Accepted: 25 August 2020
Johannes Steinfurt · Christoph Bode · Thomas S. Faber
© The Author(s) 2020
Mahaim pathway potential revealed by high-resolution three-dimensional mapping
Department of Cardiology and Angiology, University Heart Center Freiburg—Bad Krozingen, Faculty of Medicine, University of Freiburg, Freiburg, Germany
Case report A 20-year-old woman was admitted for recurrent wide complex tachycardia (. Fig. 1). The baseline electrocardiogram (ECG) showed normal sinus rhythm with a short PR interval of 130 ms, absence of septal Q waves, and no manifest pre-excitation (. Fig. 2). Echocardiography was unremarkable. Programmed atrial stimulation resulted in stim-V interval prolongation with increased preexcitation (HV shortening) and induction of antidromic echo beats with concentric atrial activation (. Fig. 3) followed by atrioventricular reciprocating tachycardia (AVRT) matching the clinical tachycardia. The tachycardia was reset and terminated by a single ventricular extrastimulus. The
morphology (. Fig. 1) and the response to pacing maneuvers were compatible with a decremental atriofascicular Mahaim pathway as the antegrade limb of the AVRT circuit [1]. Due to low success rates of conventional, fluoroscopyguided cases to detect a Mahaim potential [2], a three-dimensional (3D) mapping approach (CARTO 3, Biosense Webster, Irvine, CA, USA) was chosen. A sharp and consistent “M” potential was recorded at the lateral tricuspid annulus (TA) (. Fig. 4) using a multielectrode Pentaray catheter (Biosense Webster) with small, tightly spaced electrodes and a steerable Agilis sheath (St. Jude Medical/Abbott, USA). Radiofrequency ablation at this location elicited Mahaim automaticity (. Fig. 5) and the tachycardia became non-inducible. The
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Fig. 1 9 Clinical tachycardia. Wide complex tachycardia at a rate of 170 bpm with left axis deviation, late transition left bundle branch block, and QRS duration of 138 ms indicating an origin at the right ventricularfree wall insertionof the moderator band where the right bundle arborizes
Herzschrittmachertherapie + Elektrophysiologie
Case Reports
Fig. 2 9 Baseline 12-lead electrocardiogram
Fig. 3 8 Antidromic echo. The atrial premature beat is conducted antegrade over the accessory pathway followed by retrograde His activation and an antidromic echo beat with retrograde block in the AV node. Note long stim-V interval, left axis deviation and left bundle branch block pattern in V1 after S2.HRA high right atrium, CS coronary sinus, RVa right ventricular apex
Herzschrittmachertherapie + Elektrophysiologie
Fig. 4 8 Mahaim potential. Mahaim “M” pathway potential recorded on the inner bipoles (7.8 and 11.12) of the Pentaray catheter (Biosense Webster, Irvine, CA, USA) facing the lateral TA. Ablation tags indicate sites with Mahaim automaticity during radiofrequency ablation
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Fig. 5 8 Mahaim automaticity. Mahaim automaticity induced by radiofrequency ablation (3
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