Effects of desipramine on autonomic input to the heart.

OBJECTIVE: To examine the impact of age on the effects of desipramine (DMI) on autonomic input to the heart. METHOD: Twenty-four-hour electrocardiograms were obtained from 42 subjects, aged 7 to 66 years, while off and on DMI. To obtain measures of autonomic input to the heart, heart rate variability was assessed via spectral analysis of RR interval variability. RESULTS: DMI treatment was associated with a significant increase in 24-hour mean heart rate and significant decreases in RR interval variability in all spectral bands, including in the high-frequency band, which provides a measure of parasympathetic input to the heart. RR interval variability was greater in younger individuals both off and on DMI. CONCLUSIONS: DMI treatment was associated with a marked decline in RR interval variability, indicating that DMI affects autonomic input to the heart. Specifically, DMI reduced parasympathetic input, which, in theory, may increase vulnerability to arrhythmias. However, the magnitude of DMI's impact on RR interval variability did not vary with age.

Cardiovascular effects of desipramine in children and adults during exercise testing.

OBJECTIVE: In light of recent reports of sudden death in children being treated with desipramine (DMI), 3 of which were associated with physical exercise, the authors examined the effects of DMI on exercise in children and adults before and during DMI treatment. METHOD: Before treatment, 22 subjects (9 children, 13 adults) participated in a graded treadmill exercise test. Outcome measures included exercise tolerance, cardiovascular, and electrocardiographic parameters at progressive intensity levels and serum norepinephrine (NE) levels before and after exercise testing. Subjects were then treated with DMI, titrated to an average DMI dosage of 3 mg/kg, and underwent repeated exercise testing. RESULTS: DMI treatment was associated with a significant elevation of circulating NE levels in the pre-exercise assessment. Exercise tolerance was not affected by DMI, and blood pressure and heart rate effects were modest. The cardiovascular impact of DMI treatment was similar in children and adults. One 31-year-old subject exhibited a brief episode of ventricular tachycardia associated with exercise during DMI treatment. CONCLUSIONS: DMI has only minor effects on the cardiovascular response to exercise, and these effects do not appear age-related. However, DMI may increase the risk of exercise-associated arrhythmias in rare individuals.

Open trial of fluoxetine in children and adolescents with dysthymic disorder or double depression.

BACKGROUND: Chronic depressions commonly present in youth and cause significant morbidity. No treatment studies in this age group are currently available. METHODS: 19 pediatric subjects with dysthymic disorder or 'double depression' were recruited. After four weeks of psychosocial treatment, subjects failing to improve began open treatment with fluoxetine (20 mg) for eight weeks. Subjects were then reassessed for treatment response. RESULTS: Fifteen subjects entered the medication phase, and eleven (73%) no longer met criteria for dysthymic disorder or Major Depression at final assessment. CONCLUSIONS: Fluoxetine shows promise as a safe and effective treatment for youth with chronic depressions. Controlled trials are indicated. LIMITATIONS: Open label design, no comparison treatment condition. CLINICAL RELEVANCE: As in adults, treatment with antidepressants may prove to be a useful intervention with children and adolescents with chronic forms of depression.