Accessory Nodoventricular (Mahaim) Fibers: A Clinical Review

The electrocardiogram during sinus rhythm and tachycardia in patients with Mahaim fibers

“…The latter is considered to be normal in the majority of patients with atriofascicular pathways and patients with long atrioventricular (AV) decrementally conducting accessory pathways. Minimal preexcitation is reported to occur from 0% to 30% (13,14,16,17), and apart from the absence of q waves in the left precordial leads (18), no specific QRS pattern has been described. The purpose of this article is to report on ECG findings in a large series of patients with the Mahaim fiber during sinus rhythm and tachycardia, with emphasis on a particular ECG pattern in lead III during sinus rhythm.…”

Cardiac Mapping in Variants of the Ventricular Preexcitation Syndrome

“…When we realized the high prevalence of the rS pattern in lead III in our patients we examined previous reports dealing with decrementally conducting AV bypass tracts. We did find the rS pattern in lead III in many ECGs considered as normal in cardiology journals [13,14] and textbooks [15,16]. This suggests that the reported low figures of abnormal ECGs in patients with Mahaim bypass tracts is an underestimation.…”

“…Adenosine induced conduction block in the Mahaim fiber in 11 of the 12 patients tested. Other authors also found that atriofascicular pathways are sensitive to adenosine [9,14]. Another difference was the occurrence of heat induced automaticity during radio-frequency catheter ablation.…”

“…Current evidence suggests that they are an accessory conduction system with a proximal AV nodal-like structure and distal branching resembling the His-Purkinje system [9,10,14].…”

Electrophysiological recognition of an atrio-ventricular mahaim fibre pathway

“…Mahaim fibres (MF) were originally described anatomically in 1938 [1]. They were shown to be conductive accessory fibres arising from either the atrio-ventricular node (AVN) or from the His bundle, with their distal insertion in the right ventricle [2][3][4].…”