Dypiridamole, a cGMP phosphodiesterase inhibitor, transiently improves theresponse to inhaled nitric oxide in two newborns with congenital diaphragmatic hernia

Introduction: Congenital diaphragmatic hernia (CDH) remains a frusta;ling c ause of respiratory failure associated with persistent pulmonary hypertensi on of the newborn (PPHN). Although inhaled nitric oxide (iNO) is effective in many infants with PPHN, it often fails to improve oxygenation in infants with CDH. As the increase in vascular smooth muscle cyclic guanosine monop hosphate (cGMP) in response to iNO may be impeded by increased phosphodiest erase type-V (PDE-V) activity, it has been suggested that: PDE-V blockade p otentiates the efficiency of iNO. Case reports: We used dypiridamole (Persantine), a specific PDE-V inhibitor , in two patients with CDH. Prenatal diagnosis showed a left-sided CDH at 2 3 weeks of gestation (GA) with intrathoracic stomach and left heart underde velopment in the one infant and a right-sided CDH at 26 weeks GA with intra thoracic liver in the other. After antenatal corticoids, planned delivery w as performed by the vaginal route at 38 weeks GA. Preoperative stabilizatio n was achieved by high frequency oscillation, iNO and inotropic support ove r 24 h. Both had early pneumothorax drained by a chest tube. Despite optimi zation of ventilatory and hemodynamic support with surfactant replacement, iNO and adrenaline, oxygenation worsened progressively. Dypiridamole was in troduced intravenously at 27 and 40 h, respectively, and improved oxygenati on over the next 12 h. However, oxygenation again deteriorated and both pat ients died. Conclusion: Dypiridamole enhanced the response to iNO in PPHN associated wi th CDH, although this effect was transient. Combined therapy of iNO with PD E-V inhibitors may improve pulmonary vasodilation in some forms of PPHN whi ch do not respond to iNO, thereby reducing the need for extracorporeal memb rane oxygenation (ECMO) and improving outcome.