Abstract
Obstructive sleep apnea (OSA) patients are at risk for increased blood pressure and carotid intima-media thickness (IMT), with pulmonary hypertension and right-sided heart failure potentially developing as well. Chronic intermittent hypoxia (IH) has been used as an OSA model in animals, but its effects on vascular beds have not been evaluated using objective unbiased tools. Previously published and current experimental data in mice exposed to IH were evaluated for IMT in aorta and pulmonary artery (PA) after IH with or without normoxic recovery using software for meta-analysis, Review Manager 5. Because IMT data reports on PA were extremely scarce, atherosclerotic area percentage from lumen data was also evaluated. IH significantly increased IMT parameters in both aorta and PA as illustrated by Forest plots (P < 0.01), which also confirmed that IMT values after normoxic recovery were within the normal range in both vascular beds. One-sided scarce lower areas in Funnel Plots were seen for both aorta and PA indicating the likelihood of significant publication bias. Forest and Funnel plots, which provide unbiased assessments of published and current data, suggest that IH exposures may induce IMT thickening that may be reversed by normoxic recovery in both aorta and PA. In light of the potential likelihood of publication bias, future studies are needed to confirm or refute the findings. In conclusion, OSA may induce IMT thickening (e.g., aorta and/or PA), but the treatment (e.g., nasal continuous positive airway pressure) will likely lead to improvements in such findings.
Highlights
Obstructive sleep apnea (OSA) and elevated systemic blood pressure tend to co-exist (Davies et al, 2000) and are associated with insulin resistance, dyslipidemia, atherosclerosis and increased risk of ischemic cardiovascular diseases
Persistent disruptions of the elastic laminae were not apparent in either the aorta or pulmonary artery (PA) (Figure 2), suggesting that if such lesions were induced by intermittent hypoxia (IH), they had recovered at the end of the normoxic period
The current study adds incremental inferential data that suggests that following chronic IH exposures mimicking OSA of relative short duration (6–8 weeks), normoxic recovery is associated with normalization of the intima-media thickness (IMT) in both aorta and PA
Summary
Obstructive sleep apnea (OSA) and elevated systemic blood pressure tend to co-exist (Davies et al, 2000) and are associated with insulin resistance, dyslipidemia, atherosclerosis and increased risk of ischemic cardiovascular diseases. The causal contributions of chronic intermittent hypoxia (IH), one of the hallmarks phenotypic features of OSA, to these cardiovascular and Vascular IMT After IH Recovery metabolic abnormalities is unclear. In the context of atherosclerosis and vascular dysfunction, increased carotid intima-media thickness (IMT) has been reported in OSA patients (Drager et al, 2005). Subsequent studies revealed independent associations between hypoxic stress and IMT in OSA (Minoguchi et al, 2005) that can be reversed by nasal CPAP (Bradley and Floras, 2009)
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