Abstract 14263: Asessment of Pulmonary Vascular Reserve Using Pharmacologic Stress Testing in Patients With Fontan Physiology

Abstract

Introduction: The presence of pulmonary vascular disease (PVD) may be under-recognized during standard hemodynamic evaluation in patients with Fontan physiology. Assessment of pulmonary vascular reserve (VR) (Δ pulmonary artery pressure/Δ cardiac index) utilizing pharmacologic stress testing could be a better way of identifying PVD in pediatric patients. The objective of this study is to diagnose Fontan patients with PVD utilizing pharmacologic stress testing. Hypothesis: Pharmacologic stress testing will unmask Fontan patients as having PVD. Methods: Single center record review of cardiac catheterizations with dobutamine administration in Fontan patients from January 2021 to June 2022. Following acquisition of baseline data on room air, a dobutamine infusion was started at 5 mcg/kg/min with dose escalation as needed until an appropriate heart rate response was achieved. Hemodynamics were reassessed at each dose interval, but data are reported at the highest cardiac index (CI). Abnormal VR was defined as > 3 mmHg/l. Results: Eighteen Fontan patients (87% male) were included. Median age at the time of catheterization was 14 (IQR 11, 16) years with mean duration of Fontan circulation of 9.9 ± 3.9 years. The primary indication for catheterization was exercise intolerance (65%). Dobutamine administration did not result in a significant change in indexed pulmonary vascular resistance (PVRi) (2.1 ± 0.8 v 2.4 ± 1.31 iWU, p = 0.21) or Fontan pressure (12 [IQR 11, 14] v 14 (IQR 12, 15), p=1.0]. Eight patients had a PVRi ≥ 2.0 iWu at baseline; while 4 (22% of the cohort) had a PVRi < 2.0 iWU at baseline but had an abnormal VR. Conclusions: PVD is common in Fontan patients but may be missed in some patients without pharmacologic stress testing. Accurate diagnosis of PVD will allow for optimization of Fontan circulation with pulmonary vasodilators.