Spontaneous changes in atrioventricular conduction in a pilot with intermittent concealed preexcitation syndrome

A case of a 36-year-old pilot with a left sided accessory pathway (Kent bundle) is presented. The electrophysiological study revealed spontaneous changes in atrioventricular conduction in both the accessory and physiological pathways, lack of retrograde conduction via accessory pathway, and constant ventriculoatrial block in the atrioventricular node during the pacing tests of the right ventricular apex. We point out the influence of the autonomic nervous system on the accessory pathway conduction as well as the clinical and electrophysiological aspects of the phenomenon observed.