LAUSR

The conductive properties of an accessory pathway cannot be automatically classified as benign, even if the conduction in the pathway is only intermittent. Introduction Wolff-Parkinson-White syndrome is defined as a combination of pre-excitation in the electrocardiogram (ECG) and symptoms related to tachyarrhythmia. The pre-excitation can be intermittent, and thus is not always present in ECG. The presence and degree of pre-excitation is dependent on characteristics of conduction through the atrioventricular (AV) node, which in turn can be affected by autonomous tone, medication, a conduction system disease, or mechanical injury. In addition to adenosine provocation test, unmasking of an accessory pathway (AP) has been reported during anesthesia, in conjunction with His bundle ablation, and after tricuspid valve replacement. There is a recent case report on a transient unmasking of an AP after aortic valve replacement. Some APs present with malignant properties, ie, they may predispose to ventricular fibrillation and sudden cardiac death because of the very short refractory period in the AP permitting remarkably fast antegrade conduction during a potential episode of atrial fibrillation. We report 2 cases involving patients in whom previously unrecognized pre-excitation was unmasked after aortic valve surgery. The incidence of newly discovered pre-excitation after aortic valve surgery or transcatheter aortic valve replacement is not known.