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Patients with a univentricular heart live with chronic hypoxia (75-85%) in their first years of life, which could affect adaptation to altitude or other hypoxic insults later in life. To test this hypothesis, we exposed 18 patients with Fontan circulation (age: 24.5 16.3-38.8 years; f/m 9/9) to simulated altitude using normobaric hypoxia (15.2% oxygen, equivalent to 2500 masl) for 24 h. In blood samples obtained in normoxia (T1, 21% oxygen) and after 24 h hypoxia after a submaximal stress test, we measured hypoxia-regulated molecules involved in angiogenesis and tissue homeostasis. A significant increase was displayed for IL-10 (p = 0.001), CCL2 (p = 0.006), ANG-1 (p = 0.001), ANG-2 (p = 0.029), FGF-1 (p = 0.001) and FGF-2 (p = 0.024). E-Selectin (p p = 0.026 at T2 compared to baseline. However, OPN and OSF-1 did not exhibit significant changes (p = 0.348; p = 0.065). Fontan patients show hypoxia-related protein patterns similar to healthy individuals despite intermittent hypoxemia, but their response to standardised hypoxia was described here for the first time, requiring further study.
Müller et al. (Tue,) studied this question.