Exercise Correlates of Electrophysiologic Assessment of Sinus Node Function in Young Individuals.

This study evaluated prospective exercise correlates of sinus node function in young individuals. Subjects for this study were 25 children and young adults who required cardiac catheterization for a symptomatic arrhythmia. Measurements of sinus node function at elechophysiological catheterization were the sinus node recovery time (SNRT) and sinoatrial conduction time (SACT). Maximal exercise testing was performed using a Bruce treadmill protocol the day prior to cardiac catheterization. Exercise measurements included resting heart rate, peak heart rate, cardiac acceleration from rest to 3 minutes, from rest to 6 minutes, from rest to peak, and from 3 to 6 minutes, cardiac deceleration from peak to 1 minute postexercise, deceleration for each minute of recovery, recovery heart rates for each of 5 minutes postexercise, heart rate at which respiratory exchange ratio >1.0 and slope of the heart rate - VO curve. Exercise testing did not predict intracardiac measures of sinus node function either as a group ("normal" vs. "abnormal" groups) or individually.