Effects of posture, effort and psychophysiological activation on atrio-ventricular node and Kent bundle refractoriness.

A new protocol is described for non-invasive evaluation of electrophysiological effects of autonomic nervous system on both normal and abnormal atrio-ventricular conduction in patients with Wolff-Parkinson-White (WPW) syndrome. In 64 WPW patients with stable Kent-type ventricular preexcitation transoesophageal atrial pacing has been carried out to quantify changes in both atrioventricular (AV) node and Kent bundle refractoriness and maximal conductive capability induced by posture, physical exercise and psychophysiological activation. A significant shortening of AV nodal and accessory pathway refractory periods was found, induced by manoeuvres enhancing the sympathetic outflow, being the AV node the most sensitive structure. This finding suggests that an exhaustive investigation protocol of WPW patients should include the evaluation of the neurovegetative effects on cardiac electrophysiological parameters, under conditions which can reproduce as close as possible the individual situations a patient has to face in his real life.