The heart rate of Romano-Ward syndrome patients

The Romano-Ward prolonged QT syndrome is associated with an abnormality of ventricular recovery, rendering the patients susceptible to life-threatening ventricular arrhythmias. The pathophysiology has not been clearly defined. It has been proposed that the syndrome involves disparity of right and left cardiac sympathetic activity, with the left side dominant. This could be the result of left-sided overactivity or right underactivity. The right-sided nerves contain the chronotropic fibers, which affect heart rate. A deficiency of the effect of the right-sided nerves might, therefore, be manifest by slower heart rates. To examine this possibility, the resting heart rates of 58 Romano-Ward syndrome patients were compared to those of 255 age-matched normal controls. A significant difference in resting heart rate was observed between the Romano-Ward syndrome patients and the normal controls in newborns and children up through age 3 years. No difference was present in older children or in adults. The data are consistent with right-sided sympathetic deficiency manifest by a slower heart rate at birth and during early years of life, when sympathetic tone is high and contributes to resting heart rate, but not in older children or in adults in whom resting heart rate is principally under parasympathetic control.