Postural sway and cerebral oxygenation responses to an orthostatic challenge in patients with congenital heart disease

Patients with Fontan circulation (FTN) often exhibit altered neurodevelopment accompanied with impaired cardiovascular reflexes. Whether such differences converge and affect balance and cerebrovascular regulation during physiological orthostatic stress remains unknown. Therefore, we tested the hypothesis that patients with FTN would display greater postural sway coupled with altered blood pressure responses and lower frontal lobe oxygenation during a sit-to-stand maneuver compared to healthy matched controls (CTL). Seven patients with FTN (4 females, 3 males, 14±3.7 yrs) and seven CTL (4 females, 3 males, 17±4.4 yrs) performed 5 repeat sit-to-stand trials (sit: 30-s, stand: 30-s) and responses were averaged to yield a single response profile. Postural sway (quantified from center-of-pressure trajectories recorded on a force platform), beat-by-beat blood pressure (finger cuff photoplethysmography) and frontal lobe oxygenation (functional near-infrared spectroscopy) were measured. Lateral postural sway in response to standing was similar between groups (CTL=3.7±2.0kg vs. FTN=4.7±2.6 kg, P = 0.50). Mean arterial pressure at baseline was similar between groups (CTL=82±11mmHg vs. FTN=72±12mmHg vs P = 0.16). In response to standing, reductions in mean arterial pressure were similar between groups (CTL=-12±5.1mmHg vs. FTN=-11±15mmHg, P = 0.89). Baseline frontal lobe oxygenation was lower in FTN relative to CTL (CTL=70±4.4% vs. FTN=61±4.8%, P = 0.01). In response to standing, delta oxygenation was similar between groups (CTL=0.17±0.33% vs FTN=0.14±0.52%, P = 0.92). Together, these data indicate postural sway, blood pressure and cerebral oxygenation responses to an orthostatic challenge remain intact in patients with FTN. Nevertheless, patients with FTN displayed lower cerebral oxygenation which may contribute to neurocognitive complications in this vulnerable population. Funding: Saskatchewan Centre for Patient-Oriented Research, Canadian Institute of Health Research, Scottish Rite Charitable Foundation of Canada, Heart and Stroke Foundation of Canada) This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.