Sildenafil Ameliorates Acute Adaptive Failure to New Pulmonary Circulation after　a Bidirectional Cavopulmonary Shunt in Children

Abstract

Background: Bidirectional cavopulmonary shunts (BCPS) in univentricular heart often cause elevated transpulmonary gradient (TPG) and oxygen desaturation in the acute postoperative period, presumably due to adaptive failure to the new pulmonary circulation. Sildenafil, a PDE5 inhibitor, is widely used as a promising selective pulmonary vasodilator in the treatment of postoperative severe pulmonary hypertension. We tested the hypothesis that sildenafil ameliorates impaired pulmonary circulation after BCPS.
Method: Sildenafil treatment was indicated when TPG was elevated more than 10 mmHg with oxygen desaturation occurred despite high FiO₂ upon completion of BCPS. Sildenafil was administered by enema at a starting dose of 0.5 mg/kg following admission to the ICU. The dose was carefully increased stepwise by 0.5 mg/kg every 4 hours up to a maximum of 2 mg/kg. We retrospectively reviewed eight patients of BCPS treated with sildenafil. Age: 7.5 months (5-50); BW: 6.5 kg (5.7-13.8); diagnosis: DILV-3; unbalanced AVSD/hypoplastic LV-3; PA/IVS-1; and ccTGA/hypoplastic LV-1.
Results: Mean pulmonary artery pressure and TPG significantly decreased with hemodynamic improvement after sildenafil administration from 18.1 ± 3.1 to 11.5 ± 2.6 mmHg (p < 0.05) and 12.6 ± 1.5 to 7.4 ± 2.4 mmHg (p < 0.05), respectively. Oxygenation indicated by PaO₂ / FiO₂ ratio improved significantly after sildenafil administration from 56.3 ± 18.8 to 149.2 ± 52.5 (p < 0.05). None of the patients required nitric oxide inhalation, and no significant adverse events occurred.
Conclusion: Sildenafil is a safe and effective treatment in the postoperative management of acute maladaptive pulmonary circulation after BCPS.