Tricyclic antidepressants and cardiac autonomic control in children and adolescents

Objective: To elucidate the effects of tricyclic antidepressants on sympathetic and vagal modulation of heart rate variability. Method: Seventy-five children and adolescents (mean age 10.5 years, SD 2.0) from therapeutic and regular schools underwent challenges of paced breathing and orthostatic postural change, while heart rate was continuously recorded. Teachers completed dimensional ratings of behavior to quantify anxiety and conduct disorder. Spectral analysis of heart rate variability was utilized to decompose the postural (sympathetic) and respiratory (vagal) contributions to beat-to-beat variations in heart rate. Results: Under conditions in which cardiac vagal effects were expected to predominate, subjects medicated with tricyclic antidepressants (n = 13) showed significantly reduced vagal modulation of heart rate variability (F[5,69] = 5.23, p <.003), higher heart rates (F[5,69] = 5.54, p <.002), and higher relative sympathovagal balance (F[5,69] = 5.51, p <.002) than nonmedicated (n = 42) and medicated comparison groups (n = 20), even after controlling for the effects of age and psychopathology. Conclusions: The relative loss of cardiac vagal control in young subjects medicated with tricyclic antidepressants, considered in the context of factors known to be associated with the development of tachyarrhythmias, presents as yet another risk, especially when coupled with factors such as maturational effects and psychopathology.