Vasopressin and Inhaled Prostacyclin in Pediatric Pulmonary Hypertension

Background: Pulmonary hypertension (PH) is a rare, but devastating disease that affects both adult and pediatric patients. Mortality is high with 84% survival at one year and 50% survival at five years in adult populations despite treatment. The cause of death is typically either from right ventricular failure or sudden cardiac death, likely secondary to a pulmonary hypertensive crisis. The resuscitation of patients with PH after cardiac arrest is extremely difficult. The use of epinephrine, a pulmonary vasoconstrictor, during resuscitation may impair filling of the left ventricle. The ideal resuscitation drug(s) would dilate the pulmonary vascular bed to help fill the left ventricle while constricting the systemic vascular bed to maintain coronary perfusion. Objectives: The assessment of pulmonary vascular reactivity is critical to the clinical management of patients with pulmonary hypertension (PH). The goals of this pilot study include determination of the hemodynamic effects of low dose vasopressin infusion and the effects of a combination of low dose vasopressin infusion and inhaled prostacyclin in a population of pediatric patients with PH. Methods: The investigators propose a prospective, pilot study to examine the acute hemodynamic effects of low dose vasopressin infusion and the combination of low dose vasopressin infusion and inhaled prostacyclin in pediatric pulmonary hypertension patients. The investigators anticipate recruiting 10 pediatric patients with pulmonary hypertension over the course of one year. Study Protocol: The study will be performed in the cardiac catheterization laboratory. All subjects will be intubated and mechanically ventilated for the study as per laboratory protocol. Sedation and anesthesia will be performed at the discretion of the pediatric anesthesiologist to provide a consistent anesthetic during the period of hemodynamic study. Arterial and venous access will be obtained via the femoral approach by standard techniques. Right and left catheterization will be performed to record hemodynamic measurements at baseline and after pulmonary vasoreactivity testing with oxygen and nitric oxide as per usual. Catheterization data to be collected includes right atrial pressure, systolic, diastolic and mean pulmonary artery pressure, pulmonary capillary wedge pressure, systemic arterial pressure, cardiac index, pulmonary vascular resistance (PVR) index, systemic vascular resistance (SVR) index and PVR/SVR ratio. After a period of time to allow for nitric oxide washout, acute vasoreactivity testing to assess the hemodynamic response to low dose vasopressin infusion followed by the combination of low dose vasopressin infusion and inhaled PGI2 will be performed.