Table 3.
Key findings of included studies examining cardiovascular outcomes of sleep-disordered breathing (SDB) in children with Down syndrome (DS).
| Study | OSA metrics | CV Outcomes | Main Result | Notable Statistics |
|---|---|---|---|---|
| O’Driscoll et al. (2012) | Polysomnography with event-level analysis (NREM/REM). | ΔHR at event termination, oxygen resaturaion time, and urinary catecholamines | In children with DS (vs. controls): (1) HR surge at the end of obstructive events was significantly smaller (blunted) during NREM sleep; (2) reoxygenation after obstructive events was delayed; (3) overnight sympathetic activation was lower. | Post-event HR increase was lower in DS (NREM: +21.4% vs +26.6% in controls). Urinary catecholamines were significantly reduced in DS (noradrenaline P<0.01; adrenaline P<0.05; dopamine P<0.01). |
| Goffinski et al. (2014) | PSG in symptomatic infants | OSA prevalence/severity; co-morbid predictors (including congenital heart disease). | OSA was extremely common in infants with DS (minimum prevalence 31% overall; of those tested, 95% had OSA, 71% with severe OSA). Dysphagia and congenital heart disease were strong co-predictors of OSA in these infants. | The combination of dysphagia + congenital heart disease predicted 36% of OSA cases (overall predictive accuracy 71%). |
| Konstantinopoulou et al. (2015) | PSG parameters (AHI; arousal index; SpO2 nadir) | Echocardiography (lateral E/e′, LV mass z-score, TAPSE); BNP; daytime sleepiness scores. | Worse LV diastolic function (higher E/e′) was associated with more severe OSA (higher AHI, higher arousal index) and with deeper desaturations (lower SpO2 nadir) | E/e′ vs. AHI r = 0.61 (P = 0.002); vs. arousal r = 0.42 (P = 0.043); vs. SpO2 nadir r = −0.61 (P = 0.002); CPAP hours vs. E/e′ r = −0.48 (P = 0.044) |
| Sawatari et al. (2015) | Caregiver-reported SDB symptoms (apnea pauses, snoring, arousals, nocturia, daytime naps). | Presence and type of congenital heart disease. | Certain CHD subtypes were associated with higher likelihood of reported apnea. Children with tetralogy of Fallot had significantly higher odds of observed apneas. Conversely, snoring was reported less frequently in children with congenital heart disease. | DS children with TOF had higher odds of apnea than those without congenital heart disease (OR ~3.1, 95% CI 1.36–7.05, P<0.01). |
| Bassam et al. (2021) | Full PSG; OSA group (DS) matched to a control OSA group by AHI, and a control group without OSA. | Nocturnal HR dipping; nocturnal BP dipping (via PTT). | Children with DS + OSA showed attenuated nocturnal HR dipping across all sleep stages and reduced BP dipping (significantly in N2 stage) compared to both TD children with OSA and those without OSA. | A smaller proportion of DS children exhibited >10% decline in HR from wake to N2 or REM (vs. control with OSA). In DS, PTT was higher (indicating less BP drop) in N2 compared to control. |
| Walter et al. (2024) | PSG with analysis of obstructive & central events in NREM and REM. | ΔHR and ΔPTT from pre-event to post-event (magnitude of HR and BP surges). | Children with DS had significantly smaller HR and BP surges at respiratory event termination across event types and sleep stages, compared to TD controls. | For obstructive events, the percentage increase in HR from late-event to post-event was significantly lower in DS (in both NREM and REM, P<0.05). For central apneas, the HR surge was lower in DS during REM (P<0.01). The increase in PTT (reflecting BP rise) was smaller in DS for both NREM and REM. |
| Walter et al. (2025) | PSG; calculation of Sleep Apnea-Specific Hypoxic Burden | Heart rate variability (HRV) as an autonomic function measure; morning ΔHR (change in HR upon awakening). | Hypoxic burden was higher in children with DS (especially in primary snoring and mild OSA) than in severity-matched TD children. In DS children, a higher hypoxic burden was associated with dampened autonomic activity (lower HRV), whereas in TD children hypoxic burden was not as strongly related to HRV. | In the DS group, hypoxic burden accounted for a significant proportion of variance in heart rate variability (R2 = 0.12, β = –10.6 ± 4.6, P = 0.03), indicating that greater oxygen desaturation load predicted reduced autonomic responsiveness. |
Data include study-level sleep metrics [apnea-hypopnea index (AHI), polysomnography (PSG) features, non-rapid eye movement (NREM) and rapid eye movement (REM) sleep], cardiovascular outcomes [heart rate (HR), change in heart rate (ΔHR), heart rate variability (HRV), blood pressure (BP), pulse transit time (PTT), tricuspid annular plane systolic excursion (TAPSE), left ventricular (LV) mass, mitral lateral E/e′ ratio], and biomarkers [B-type natriuretic peptide (BNP), urinary catecholamines]. The table summarizes main results and notable statistics across studies, highlighting consistent evidence of autonomic blunting, impaired nocturnal dipping, elevated hypoxic burden, and early cardiac structural changes in this population.