Comparative effects of age and sedation on sinus node automaticity and atrioventricular conduction.

Corrected sinus node recovery time (CSNRT) and atrioventricular node effective refractory period are longer in nonsedated adults than in sedated children at cardiac catheterization. We attempted to ascertain the relative contributions of age and catheterization sedation on these differences by studying adult beagles and beagle puppies previously instrumented with atrial pacing wires. We found that CSNRT was similar in adults and puppies prior to drug administration. CSNRT shortened significantly after meperidine, promethazine, and chlorpromazine (DPT) administration in both adult dogs and puppies. Atrioventricular node effective refractory period (AVERP) was shorter in puppies than adults prior to DPT, and did not shorten in in either group after DPT. These findings suggest that the difference between CSNRTs in children and adults can be at least partly explained by the sedation used in children. This is an important consideration when premedicating children for electrophysiologic studies, particularly in children with suspected sinus node dysfunction.