Accessory pathway (AP)

An accessory pathway is an aberrant bundle of myocardial tissue that forms an abnormal electrical connection between atrial and ventricular chambers of the heart, bypassing the normal atrioventricular node. This results from incomplete insulation of atrial from ventricular myocardium during embryological development. Accessory pathways allow electrical impulses to circumvent physiological conduction delay, which can cause various arrhythmias, including atrioventricular re-entrant tachycardia and pre-excitation syndromes such as Wolff–Parkinson–White syndrome. Accessory pathways are classified by their anatomical location, conduction direction (anterograde, retrograde, or bidirectional), and conduction properties (decremental or non-decremental). They are not molecular targets but rather pathological substrates for arrhythmia and are treated by ablative procedures or antiarrhythmic drugs that modulate cardiac conduction.

Other names

Bypass tractKent bundle/fiberMahaim fiber (specific subtypes)accessory conduction pathwayatrioventricular accessory pathway

Slowing conduction through the accessory pathway or AV node, terminating arrhythmia circuits, suppressing conduction velocity in cardiac tissue