High-Risk Patients with Ventricular Preexcitation — A Pendulum in Motion

Since they were first described, preexcitation syndromes have intrigued physicians. The interest derives in part from the myriad bizarre electrocardiographic abnormalities associated with these syndromes and from the variety of complex arrhythmias that may be manifested in affected patients. Symptomatic tachycardias develop in patients with the Wolff–Parkinson–White syndrome because there is conduction over an accessory (extranodal) atrioventricular pathway consisting of working myocardium. Since an impulse arising from the sinus node can activate the atrioventricular node and the more rapidly conducting accessory pathway in parallel, the ventricle ipsilateral to the site where the accessory pathway enters the myocardium is excited prematurely. . . .