"Manhaim Fibers" Atrioventricular Reentrant Tachycardias. Electrocardiographic and Electrophysiologic Characteristics

pp 645-657

Abstract

Objectives

This reportdescribes the electrocardiographic and electrophysiologic findings in eleven patients who showed accessory pathways with "Mahaim fibers electrophysiology characteristics".

Material and method

Eleven patients (8 females) between 12 and 64 years old (mean: 28.2 ± 14.3years), showed antidromic atrioventricular tachycardia with left bundle branch block pattern. Ten of them had right atriofascicular pathways and another a long right atrioventricular pathway. Two patients had associated atrioventricular nodal reentry tachycardia and another two patients typical atrioventricular accessory pathways. Through multipolar catheters high right atrium, His bundle, right bundle branch, coronary sinus and right ventricular apex electrograms were recorded in sinus rhythm and during tachycardias.

Results

Right atriofascicular and long right atrioventricular pathways exhibited only anterograde conduction with decremental properties. Tachycardias showed long AV and short VA intervals (except those with right bundle branch block or retrograde atrioventricular accessory pathway conduction). Patients with atriofascicular pathways had both narrower QRS complexes (mean: 119.5 ±150 m sec)and r wave (< 40 m sec) in leads V2-V4 than the patient with long atrioventricular pathway. Patients with atriofascicular pathways showed ear-lier ventricular activation at right ventricular apex (RVA-QRS: mean, 7 ± 3.5 versus -30 m sec) and, those without right bundle branch block, earlier right bundle branch (RBB-QRS: mean, 1.4 ± 4.8versus -15 m sec) and His bundle (HV: mean, -10.7± 7.8 versus -25 m sec) retrograde activation than the patient with long atrioventricular pathway. Atrial extra stimuli introduced after inscription of the septal atrial electrogram advanced the timing of the QRS complex ressetting the tachycardia.

Conclusions

In our small study population the anatomic sustrate of accessory pathways with "Mahaim fibers electro-physiology characteristics" was a right atriofascicular pathway in ten patients and a long right atrioventricular pathway in one. No patients showed nodoventricular or nodofascicular pathways.