Aortic Stiffness, Flow-Mediated Dilatation and Carotid Intima-Media Thickness in Obstructive Sleep Apnea
Pamukkale University, Denisli, Denizli, Turkey Respiration
(Impact Factor: 2.59).
11/2006; 73(6):741-50. DOI: 10.1159/000093531
Obstructive sleep apnea (OSA) has a critical association with cardiovascular mortality and morbidity. Carotid intima-media thickness (IMT), flow-mediated dilatation (FMD) and aortic stiffness are early signs of atherosclerosis. The presence of subclinical atherosclerosis was assessed in OSA patients using these parameters.
40 patients with OSA showing an apnea-hypopnea index (AHI) > or =5 (mean age 51.3 +/- 9 years, 32 males) and 24 controls (AHI < 5, mean age 51.9 +/- 5.2 years, 19 males) were enrolled in the study. In all subjects, polysomnographic examination and recordings were performed during sleep. IMT of the carotid artery, endothelium-dependent/-independent vasodilation of the brachial artery and aortic elastic parameters were investigated using high-resolution Doppler echocardiography.
The demographic data of the patients with OSA and controls were not significantly different. Subjects with OSA demonstrated higher values of aortic stiffness (7.1 +/- 1.88 vs. 6.42 +/- 1.56, respectively) and IMT (0.85 +/- 0.13 vs. 0.63 +/- 0.11 mm, p = 0.0001, respectively) but lower distensibility (9.47 +/- 1.33 vs. 11.8 +/- 3.36 cm(2)/dyn/10(6)) and FMD (4.57 +/- 1.3 vs. 6.34 +/- 0.83%, p = 0.0001, respectively) than the controls. The respiratory disturbance index correlated positively with aortic stiffness and IMT and negatively with distensibility and FMD.
We observed blunted endothelium-dependent dilatation, increased carotid IMT and aortic stiffness in patients with OSA compared with matched control subjects. This is evident in the absence of other diseases, suggesting that OSA is an independent cause of atherosclerosis. These simple and non-invasive methods help to detect subclinical atherosclerosis in OSA.
Available from: Michael J Blaha
- "Study population is a subset of a cohort study. Tanriverdi et al., 2006  N ¼ 64 OSA: "
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ABSTRACT: Patients with obstructive sleep apnea (OSA) have a high burden of cardiovascular disease (CVD) but a causal relationship between OSA and atherosclerotic CVD remains unclear. We systematically reviewed the literature analyzing the relationship. A review of the Medline database for studies noninvasively evaluating subclinical CVD in OSA was conducted. A total of fifty-two studies were included in this review.
Across the studies the prevalence of atherosclerosis, as assessed by coronary artery calcification, carotid intima-media thickness, brachial artery flow mediated dilation and pulse wave velocity was higher in patients with OSA and correlated with increasing severity and duration of OSA.
This study shows OSA is an independent predictor of subclinical CVD; as CVD is more likely to occur in patients with long standing and severe OSA. Further research is however necessary to identify specific OSA populations that would benefit from aggressive screening.
Available from: Mahnoor Khan
- "Repetitive desaturation-reoxygenation sequences have been shown to generate reactive oxygen species (ROS), impair serum antioxidant capacity, and enhance lipid peroxidation . This oxidative stress is known to damage the vascular endothelium, to promote atherosclerosis, and ultimately to favor the later occurrence of adverse cardiovascular events . Therefore, a direct correlation between OSA and elevated CIMT may be elucidated . "
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ABSTRACT: Background. Obstructive sleep apnea (OSA) is associated with coronary artery disease. Intermittent hypoxia associated with OSA increases sympathetic activity and may cause systemic inflammation, which may contribute to atherosclerosis leading to an increase in the size of carotid intima media thickness (CIMT). Methods. PubMed and Cochrane library were reviewed by utilizing different combinations of key words: sleep apnea, carotid disease, intima media thickness, and carotid atherosclerosis. Inclusion criteria were English articles; studies with adult population with OSA and without OSA; CIMT recorded by ultrasound in mean and standard deviation or median with 95% confidence interval; and OSA defined as apnea hypopnea index of ≥5/h. A total of 95 studies were reviewed for inclusion, with 16 studies being pooled for analysis. Results. Ninety-five studies were reviewed, while 16 studies were pooled for analysis; since some studies have more than one data set, there were 25 data sets with 1415 patients being pooled for meta-analysis. All studies used ultrasound to measure CIMT. CIMT standardized difference in means ranged from -0.883 to 8.01. The pooled standardized difference in means was 1.40 (lower limit 0.996 to upper limit 1.803, (P < 0.0001). Conclusion. Patients with OSA appear to have increased CIMT suggestive of an atherosclerotic process.
Available from: Katarzyna Kunicka
- "Altin et al.  suggested that the frequency and grade of atheromatous stenosis is higher in patients with severe OSA and hypothesized that a high AHI is an even stronger predictor of atherosclerosis than age. Tanriverdi et al.  did not confirm this relationship, which is in line with our findings. "
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Obstructive sleep apnea (OSA) is associated with elevated risk of cardiovascular events. The early stages of vascular complications can be visualized by means of ultrasound. Intima-media thickness (IMT) correlates with the presence of risk factors of cardiovascular diseases such as hypertension, diabetes, tobacco smoking, or hyperlipidemia. However, little is known whether OSA itself may be the cause of IMT thickening.
The study group was composed of 28 patients (6 women, 22 men; mean age = 53.8 years, mean BMI = 27.1 kg/m2, mean AHI = 22.4/h) with OSA who had no comorbidities. The control group consisted of 28 healthy subjects (6 women, 22 men; mean age = 53.9 years; mean BMI = 27.5 kg/m2). In both groups IMT was assessed in common carotid arteries with the use of ultrasonography. Additionally, in patients with OSA, pulse wave velocity, echocardiography, 24-h automated blood pressure monitoring, clinical signs and symptoms, and blood tests were performed to investigate possible correlations with IMT.
Median IMT was 0.41 mm in OSA patients and 0.46 mm in the control group (p = 0.087). Echocardiography revealed left ventricle hypertrophy in 21 %, systolic disorders in 8 %, and diastolic disorders in 57 % of the patients. In a large majority of patients, pulse wave velocity was found to be normal. IMT correlated with age (r = 0.446, p = 0.017), total cholesterol (r = 0.518, p = 0.005), daytime systolic blood pressure (r = 0.422, p = 0.025), pulse pressure 24 h and daytime (r = 0.424, p = 0.027 and r = 0.449, p = 0.019), early mitral flow/atrial mitral flow (E/A) (r = −0.429, p = 0.023), and posterior wall diameter (PWD) (r = 0.417, p = 0.270).
In a relatively nonobese group of patients, no significant differences were found in the intima-media thickness between OSA patients without concomitant cardiovascular diseases and healthy controls. This may lead to the conclusion that IMT does not reflect increased risk of cardiovascular events in patients with isolated OSA.
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