Abstract
Postoperative aggravation of pulmonary hypertension after pediatric cardiac surgery due to temporary endothelial dysfunction may lead to sudden pulmonary arterial pressure rise with compromise of right ventricular function. Though treatment with inhaled nitric oxid (NO) has been successful, rebound pulmonary hypertension has been observed after NO withdrawal due to supression of endogenous NO sythase. Sildenafil has been shown to prevent this reaction and is widely used after pediatric cardiac surgery. The aim of our study was to evaluate the effectively of postoperative administration of oral sildenafil (1 mg/kg/day) in preventing postoperative pulmonary hypertensive crises. 21 patients after repair of complete atrioventricular canal (n=10) or ventricular septal defect (n=11) were randomly assigned to the study group or control group. The study group received sildenafil after surgery via nasogastric tube every eight hours for 48 hours, the control group received placebo. The primary outcome parameter was the number of pulmonary hypertensive events (spontaneous pulmonary arterial pressure rise to or above systemic arterial pressure). Secondary outcome parameters were: need for inotropic drugs, fluid balance, urinary output, days on the ventilator or in the intensive care unit (ICU). There was no difference in the number of pulmonary hypertensive events between both groups: median (IQR); 2 (0-6,5) sildenafil, 1 (0-2) placebo, p=0,67. Neither inotrope score, time on the ventilator, ICU length of stay, nor fluid balance differed significantly. Urinary output was significantly lower in the sildenafil group.
Highlights
Congenital heart defects with intracardial left to right shunting are often associated with elevated pulmonary vascular resistance [1,2]
Two patients of the sildenafil group were excluded after randomisation because of left ventricular failure and withdrawal of parental consent respectively. 8 children remained in the sildenafil and 11 children in the placebo group
Pulmonary hypertensive events There was no difference between the two study groups in the main outcome parameter: sudden pulmonary arterial pressure increase equal to or above systemic arterial pressure, 2 (0-6.5) in the sildenafil group, 1 (0-2) in the placebo group, median, p=0.67
Summary
Congenital heart defects with intracardial left to right shunting are often associated with elevated pulmonary vascular resistance [1,2]. Pulmonary hypertension often deteriorates after cardiopulmonary bypass due to temporary endothelial dysfunction and suppression of endogenous nitric oxide (NO) production. This will result in a decline of the synthesis of cyclic guanosine monophosphate (cGMP), a key player in the regulation of pulmonary vascular reactivity. Systemic inflammatory response syndrome associated with cardiopulmonary bypass regularly triggers an increase of endothelin levels, resulting in intensified pulmonary vasoconstriction. As a consequence patients born with complete atrioventricular canal (CAVC) or large ventricular septal defects (VSD) are at increased risk of postoperative pulmonary hypertensive crises with subsequent right heart failure. Postoperative recovery may be delayed as a function of pulmonary hypertension
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