Interim futility analysis

The purpose of this study is to test the efficacy of treprostinil (TRE) in the perioperative non-fenestrated, extracardiac Fontan patients in order to reduce duration of chest tube drainage (in days).

The Fontan operation is performed for patients with single ventricle physiology as the final palliation to create a series circulation, with passive systemic venous return to the pulmonary arteries and the single ventricle solely providing systemic output.

Patients undergoing extracardiac Fontan tend to have elevation of Fontan pressures immediately following the operation with inflammation from surgery requiring additional fluid administration to maintain blood pressure. Increased Fontan pressures and fluid overload lead to prolonged chest tube drainage.

The hypothesis is that treprostinil, a prostacyclin drug that dilates the pulmonary arteries, will improve immediate postoperative Fontan pressures. Treprostinil is not FDA approved for this use. Anecdotally and in a small case series, prostacyclin therapy has been shown to assist in transitioning patients off nitric oxide. The investigators believe that this improvement in hemodynamics will decrease duration of chest tube drainage resulting in a shorter length of hospital stay.

In order to understand the effect of treprostinil on Fontan patients, this study has two parts:

1. reactivity testing with inhaled treprostinil in the cardiac catheterization lab for pre-Fontan patients undergoing routine catheterization in anticipation of the Fontan operation;
2. perioperative use of subcutaneous treprostinil starting immediately pre-op until postoperative day #7 to improve immediate postoperative hemodynamics and ultimately reduce overall length of hospital stay.

The investigators hope to learn how pulmonary vasodilator therapy affects and/or improves post- operative hemodynamics following the Fontan operation. This knowledge would be very important in the care of single ventricle patients following the Fontan operation if there is improvement of immediate outcomes and reduction of hospital length of stay. On a broader scale, if the use of treprostinil in perioperative Fontan patients can achieve the same results other centers achieve with the use of a fenestration this may have wide scale implications in the nationwide treatment of Fontan patients.

Inclusion Criteria:

• Pediatric patient undergoing Fontan operation and/or pre-Fontan cardiac catheterization at Lucile Packard Children's Hospital (LPCH)

Exclusion Criteria:

• Platelet count < 50K (treprostinil can act as a platelet inhibitor and this may place patient at additional risk of bleeding if already thrombocytopenic)
• Dermatologic condition that renders the patient unable to tolerate a subcutaneous infusion (can still take part in inhaled vasodilator testing during cardiac catheterization)
• Currently receiving any vasodilator therapy specifically for the purpose of pulmonary vasodilation (phosphodiesterase type 5 inhibitor, endothelia receptor antagonist and/or prostacyclin).

Adverse event data were collected during hospitalization, which was generally between 1-3 weeks.

Early termination based on futility analysis performed prior to full study enrollment led to smaller number of subjects analyzed than initially outlined by power analysis.