accessory pathway, an abnormal conduction pathway between an atrium and a ventricle. Ventricular activation via an accessory pathway slows initial ventricular contraction, producing preexcitation and the delta wave of Wolff-Parkinson-White syndrome. The delta wave shortens the P-R interval, and broadens the QRS complex. The most common associated arrhythmias are paroxysmal supraventricular tachycardia and atrial fibrillation. Patients may be cured by transvenous radiofrequency ablation of the accessory pathway or may be treated pharmacologically.
