Accessory pathway

Some pathways may activate a region of ventricular muscle earlier than would normally occur, referred to as pre-excitation, and this may be seen on an electrocardiogram.

Accessory pathways may not require any treatment, but those causing symptoms may be treated with medication including calcium channel antagonists, beta blockers or flecainide.

[3] Alternatively, the electrical conduction through an accessory pathways can be abolished using catheter ablation, potentially offering a permanent cure.

[4] Mahaim pathways are typically seen on the right side of the heart, with their ventricular connection lying within or close to the right bundle branch.

[4] If conduction to the ventricles occurs solely through the pathway (maximal pre-excitation), as occurs during arrhythmias like antidromic atrioventricular re-entrant tachycardia, the ECG appearance is of QRS complexes with a left bundle branch block morphology which can be mistaken for ventricular tachycardia.