Semi-Invasive Pressure-Flow Plots Obtained Using Exercise Echocardiography Relate to Clinical Status and Exercise Capacity in Patients With a Fontan Circulation

Abstract

Aims: Exercise echocardiography with peripheral venous pressure measurement (CPETecho-PVP) may provide superior insights into the pathophysiology of Fontan failure compared to standard cardiopulmonary exercise testing. Accordingly, we assessed (1) the clinical and hemodynamic correlates of pressure-flow plots obtained from CPETecho-PVP in Fontan patients and (2) the relationship between pressure-flow plots and exercise capacity. Methods: Forty-one consecutive Fontan patients underwent CPETecho-PVP. Peripheral venous pressure was measured in the distal upper extremity using an 18- to 20-gauge intravenous line. A multipoint PVP/cardiac output (CO) slope was calculated as a linear approximation using linear regression analysis from individual pressure-flow plots. A PVP/CO >3 mm Hg/L/min was considered elevated. Results: Median age was 28 (range, 17-60) years; left ventricle dominance was present in 32 (78%) patients. Compared to patients with a PVP/CO slope <= 3 mm Hg/L/min (n = 29), those with a PVP/CO slope >3 mm Hg/L/min were more likely to have New York Heart Association functional class III to IV (P = .005), lung pathology (P = .004), history of atrial arrhythmia (P = .009), or thromboembolism (P = .02). Additionally, a PVP/CO slope >3 mm Hg/L/min was associated with higher N-terminal prohormone of natriuretic peptide levels (325.0 [176.3-590.0] vs 150.5 [61.3-255.0] ng/L; P = .034), lower peak oxygen consumption (peak VO2) 48.7% +/- 13.3% vs 65.2% +/- 15.3% predicted; P = .003), lower heart rate reserve (65% [42%-105%] vs 100% [75%-127%] predicted; P = .010), and lower peak cardiac index (3.8 +/- 0.8 vs 6.3 +/- 1.5 L/min.m(2); P < .001). Rest-to-peak change in heart rate (P < .001) and cardiac index (P = .006), percentage predicted forced vital capacity (P = .044), and PVP/CO slope (P = .009) were all related to percentage predicted peak VO2. Conclusions: A steeper PVP/CO plot is associated with worse clinical status, including lower exercise capacity. This supports the notion of implementing the CPETecho-PVP in the standard of care for Fontan patients.