Q. What do ypu know about Conduction Disturabances?

During exercise there is an increase in the sympathetic drive and a withdrawal of vagal tone. Sympathetic enhancement of conduction is mediated somewhat by the increased sinus firing rate causing an increased number of impulses arriving at the atrioventricular (AV node). The fatigue of the conduction tissue as a result of the increase traffic and a relatively greater segment of the conduction time being occupied by the refractory period may mitigate the effect of the excess sympathetic influence. In CAD patient, ischaemia may also alter the conduction process, depending on the severity and location. In normal individuals, the PQ interval shortens to about 110 msec.