Vasopressin and Inhaled Prostacyclin in Pediatric Pulmonary Hypertension
Vasopressin and Inhaled Prostacyclin in Pediatric Pulmonary Hypertension
To diagnose pulmonary hypertension, children have a cardiac catheterization to check the
 blood pressure in their lungs. Children with pulmonary hypertension have high blood pressure
 in their lungs. The right ventricle of the heart has to do more work to pump against this
 higher pressure. The investigators do not know the best medicine(s) to help children with
 pulmonary hypertension when their right ventricles fail. The purpose of the study is to look
 at the effects of two different medicines on the blood pressure in the lungs of a child with
 pulmonary hypertension. The investigators hope to then be able to choose the best medicine
 for children with pulmonary hypertension and right ventricular failure.

 The first medicine is called vasopressin. It is a hormone that your body makes on its own.
 The investigators will be giving it through an intravenous infusion. The investigators think
 that vasopressin works differently in different parts of your body. The investigators are
 looking to see the different effects that vasopressin has in the lungs compared to the rest
 of the body.

 The second medicine is called prostacyclin and is something that your body also makes by
 itself. Prostacyclin, given via an intravenous infusion, is a treatment for pulmonary
 hypertension as it decreases pressure in the blood vessels. In the catheterization
 laboratory, patients breathe in this medicine to measure specific changes in the blood
 pressure in their lungs.
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.
Inclusion Criteria:

 All pediatric patients with pulmonary hypertension defined as a mean pulmonary artery
 pressure ≥ 25mmHg undergoing diagnostic cardiac catheterization for clinical purposes are
 potential subjects. Subjects must have preserved left ventricular function (ejection
 fraction ≥ 40 %). Subjects must have parental consent for enrollment.

 Exclusion Criteria:

 1. Any patient with left ventricular dysfunction (EF < 40%).

 2. Any patient with known pulmonary veno-occlusive disease