Acute Hemodynamics in the Fontan Circulation: Open-Label Study of Vasopressin

OBJECTIVE: To describe the acute hemodynamic effect of vasopressin on the Fontan circulation, including systemic and pulmonary pressures and resistances, left atrial pressure, and cardiac index.DESIGN: Prospective, open-label, nonrandomized study (NCT04463394).SETTING: Cardiac catheterization laboratory at Lucile Packard Children's Hospital, Stanford.PATIENTS: Patients 3-50 years old with a Fontan circulation who were referred to the cardiac catheterization laboratory for hemodynamic assessment and/or intervention.INTERVENTIONS: A 0.03 U/kg IV (maximum dose 1 unit) bolus of vasopressin was administered over 5 minutes, followed by a maintenance infusion of 0.3 mU/kg/min (maximum dose 0.03 U/min).MEASUREMENTS AND MAIN RESULTS: Comprehensive cardiac catheterization measurements before and after vasopressin administration. Measurements included pulmonary artery, atrial, and systemic arterial pressures, oxygen saturations, and systemic and pulmonary flows and resistances. There were 28 patients studied. Median age was 13.5 (9.1, 17) years, and 16 (57%) patients had a single or dominant right ventricle. Following vasopressin administration, systolic blood pressure and systemic vascular resistance (SVR) increased by 17.5 (13.0, 22.8) mm Hg (Z value -4.6, p < 0.001) and 3.8 (1.8, 7.5) Wood Units (Z value -4.6, p < 0.001), respectively. The pulmonary vascular resistance (PVR) decreased by 0.4 +/- 0.4 WU (t statistic 6.2, p < 0.001), and the left atrial pressure increased by 1.0 (0.0, 2.0) mm Hg (Z value -3.5, p < 0.001). The PVR:SVR decreased by 0.04 +/- 0.03 (t statistic 8.1, p < 0.001). Neither the pulmonary artery pressure (median difference 0.0 [-1.0, 1.0], Z value -0.4, p = 0.69) nor cardiac index (0.1 +/- 0.3, t statistic -1.4, p = 0.18) changed significantly. There were no adverse events.CONCLUSIONS: In Fontan patients undergoing cardiac catheterization, vasopressin administration resulted in a significant increase in systolic blood pressure, SVR, and left atrial pressure, decrease in PVR, and no change in cardiac index or pulmonary artery pressure. These findings suggest that in Fontan patients vasopressin may be an option for treating systemic hypotension during sedation or general anesthesia.