Exercise catheterization in adults post-Fontan with normal and abnormal haemodynamic criteria: Insights into normal Fontan physiology

Aim: The normal (i.e. expected) haemodynamics in adults post-Fontan remain poorly delineated. Moreover, the definitions of elevated exercise pulmonary artery (PA) and PA wedge pressure (PAWP) for this population have not been described. Methods and results: Seventy-two adults post-Fontan undergoing exercise catheterization were categorized into abnormal (Group I, n = 59; defined as resting mean PA ≥14 mmHg and/or PAWP ≥12 mmHg, ΔPAWP/Δsystemic flow [Qs] >2 mmHg/L/min, and/or ΔPA/Δpulmonary flow >3 mmHg/L/min) and normal (Group II, n = 13) haemodynamics. Thirty-nine patients with non-cardiac dyspnoea (NCD) were included as controls. There was no difference in exercise arterial oxygen saturation (87% [81–92] vs. 89% [85–93], p = 0.29), while exercise PA pressure (27 [23–31] vs. 16 [14.5–19.5] mmHg, p < 0.001) and PAWP were higher (21 [18–28] vs. 12 [8–14] mmHg, p < 0.001) in Group I. At peak exercise, Group I had lower heart rate (97 [81–120] vs. 133 [112.5–147.5] bpm, p < 0.001) and Qs response (67.3 [43.8–93.1] vs. 105.9 (82–118.5) % predicted, p < 0.001) than Group II. Exercise superior vena cava pressures were higher (16 [14–22.5] vs. 5.5 [3–7.3] mmHg, p < 0.001) and arterial oxygen saturation lower (89% [85–93] vs. 97% [96–98], p < 0.001) in Group II compared to NCD, while no differences in PAWP, stroke volume index, heart rate, or Qs response were seen. If defined as two standard deviations above mean values for Group II, elevated PAWP and mean PA pressure post-Fontan would correspond to 20.6 mmHg and 25.8 mmHg, respectively. Conclusion: PAWP >20 mmHg and mean PA pressure >25 mmHg could be used to define elevated values during exercise in adults post-Fontan. The major discrepancy in exercise haemodynamics among Group II compared to controls appears to be the degree of systemic venous hypertension and arterial desaturation.