Introduction As a pulmonary vasodilator that specifically targets smooth muscles of the lungs by inhibiting PDE-5, sildenafil (Viagra, Pfizer) has brought much hope for patients with pulmonary hypertension (PHTN) within the last few years. The majority of studies on the therapeutic effects of sildenafil have been conducted on adult subjects. Knowledge of its effects on children still remains quite limited.
Hypothesis We hypothesized that administering oral sildenafil to pediatric patients for long-term use is safe and effective for treating pulmonary hypertension.
Methods A retrospective chart review was conducted on all patients who were diagnosed with pulmonary hypertension and treated with sildenafil at Loma Linda University Children's Hospital between 8/2001 through 8/2004. To assess the safety of sildenafil, side effects were noted, while its efficacy was determined by noting the change in oxygen requirement and severity of pulmonary hypertension and tricuspid insufficiency as observed by Doppler echocardiogram.
Results Of the 22 pediatric patients (mean age 4.9 years; females 50%), three patients had primary PHTN and 19 patients had secondary PHTN. The average duration for sildenafil treatment was 5.0 months with an average dose administration of 1.5 mg/kg/day. Three (13.6%) patients reported adverse effects, which included nausea, vomiting, diaphoresis, and tachypnea. No report of systemic hypotension was noted. The oxygen requirement at the start and end of the treatment decreased in 16 (73%) patients, while an increase in oxygen need was present for 5 (23%) patients. The remaining one (5%) patient had no change in oxygen requirement. As observed by Doppler echocardiography, PHTN improved in 12 (55%) patients, worsened in 1 (5%) and remained unchanged or was unknown for 9 (41%). Tricuspid insufficiency improved in 7 (32%) patients, worsened in 1 (5%) patient and remained unchanged or was unknown for 14 (64%) patients.
Conclusion This preliminary retrospective study demonstrates that long-term sildenafil therapy appears to be safe and efficacious for pediatric pulmonary hypertension. However, this pediatric study is under powered to evaluate the potential for irreversible retinal damage linked to PDE-5 inhibition in some adult studies. Additional studies are needed to evaluate for rebound PHTN after withdrawal of sildenafil.