Obstructive Sleep Apnea Is Associated With Greater Thoracic Aortic Size

Abstract

Obstructive sleep apnea (OSA), characterized by partial or complete occlusion of the pharynx during sleep, results in persistent inspiratory effort and interruption of airflow. During each episode of apnea, OSA patients develop increased transmural pressure in the aortic wall. Accordingly, to test the hypothesis that the presence of OSA would be associated with greater thoracic aortic size, we prospectively assessed 150 consecutive patients, newly referred to the sleep clinic in our institution, in a crosssectional study to confirm OSA. The patients underwent sleep study and chest computed tomography (CT)-derived thoracic aortic diameter. In this particular period, a chest CT was performed within 3 months of the sleep study upon informed consent to our protocol. Exclusion criteria included: 1) prior history of aortic dissection, aortic valvular disease, and clinical characteristics of Marfan's syndrome; 2) central sleep apnea; 3) treatment for sleep apnea; and 4) dialysis. The outer diameter of the ascending aorta was measured by caliper within the CT image. Overnight sleep study was performed using cardiopulmonary monitoring (Morpheus, Teijin Inc., Tokyo, Japan). The apnea-hypopnea index (AHI) was quantified as the frequency of apneas and hypopneas per hour of bed time. OSA was defined as AHI Ն10/h. The data are presented as mean Ϯ SD or frequencies. To determine the independent factors, the multiple linear regression model with backward elimination technique was used, including older age, male gender, blood pressure, hypertension, dyslipidemia, diabetes mellitus, ischemic heart disease, smoking, and AHI. Comparisons between the 2 groups were performed by Student t test for the unadjusted aortic diameter and by analysis of covariance for the adjusted aortic diameter.The patients' mean age was 60 Ϯ 11 years; 125 (83%) were men, with mean body mass index of 24.7 Ϯ 3.1 kg/m 2 . Fifty-nine percent of patients had hypertension. At assessment, 91% of patients had already taken prescribed antihypertensive medications. One hundred ten patients (73%) had OSA. On univariate analysis, older age, male gender, body mass index, systolic blood pressure, pulse pressure, hypertension, dyslipidemia, ischemic heart disease, and AHI were positively correlated with thoracic aortic size. On multivariate analysis, older age (per 10-year increase, coefficient 1.82, 95% confidence interval [CI]: 1.13 to 2.34, p Ͻ 0.001), male gender (coefficient 3.25, 95% CI: 1.63 to 4.87, p Ͻ 0.001), and AHI (per 10-event/h increase, coefficient 0.62, 95% CI: 0.25 to 0.98, p Ͻ 0.001) remained as factors associated with greater thoracic aortic diameter. Contrarily, there was no significant independent relationship between blood pressure/hypertension and thoracic aortic size. Additionally, patients with OSA had a significantly greater thoracic aortic size than those without OSA (p Ͻ 0.001) (Fig. 1), even if adjusted for older age and male gender (p Ͻ 0.001).Increased thoracic aortic size is known to be related to aging, male, genetic mutation including M...

The impact of obstructive sleep apnoea on the aorta

“…Most of the studies investigated the association between OSA and the aortic root diameter [44][45][46][47][48][49][50][51][52]. Six cross-sectional studies investigating patients referred for a sleep evaluation reported a positive association between the aortic root diameter and parameters of OSA severity (either AHI or oxygen desaturation index (ODI)) [45,[48][49][50][51][52]. Notably, one study found an association with AHI in rapid eye movement sleep only where the severity of OSA becomes greater, partly due to a decreased respiratory muscle tone [52].…”

“…These variations include, for example, the facts that the treatment status of OSA was not taken into account [46], common diagnostic criteria have not been consistently applied [45,47,51] and some studies lacked a control group [46,58,60]. In studies assessing the thoracic aorta there is also a high between-study variation in methodological aspects, as studies do not use consistent anatomic landmarks [41,[44][45][46][47][49][50][51]. When considering conflicting results among thoracic and abdominal diameters measured at different anatomic landmarks and the fact that, even in a single study, aortic diameters at different landmarks were distinctly affected by OSA, one may hypothesise that the aetiological significance of OSA may vary along the aorta [53].…”

“…Furthermore, specific OSA severity groups are often not reported and are most likely underpowered [41, 44-46, 50, 51, 61]. The latter represents a limitation, as the results of several studies suggest that the more severe end of the OSA spectrum (AHI ⩾30 events·h A significant proportion of studies in this review were submitted in the form of short notes [51,58] or correspondence letters [45,50], or their main outcome was something other than aortic diameter [44]. Therefore, they were originally designed with an objective other than investigating the association between OSA and aortic dilation.…”

“…Therefore, they were originally designed with an objective other than investigating the association between OSA and aortic dilation. The possibility exists that the initial finding of a statistically significant association between OSA and aortic diameter evoked authors to selectively report their (mostly positive [45,50,51,58]) data, thus creating a publication bias. Finally, studies on the prevalence of aortic disease in OSA patients are lacking.…”

Therapeutic Efficacy of Continuous Positive Airway Pressure in Obstructive Sleep Apnea Patients with Acute Aortic Dissection: a Case Report

“…In the future, examination of whether treatment of OSA is involved in aortic diameter diminution is necessary. In connection, Serizawa, et al recently suggested that OSA may contribute to increased thoracic aortic size through mechanical stress on the aortic wall due to repeated episodes of apnea and hypopnea, independently of systemic hypertension 11) . Moreover, G. Sampol, et al, showed that patients with aortic dissection (n 19) had a significantly larger AHI than patients with matched age, sex, BMI, blood pressure and neck circumference (n 19), and that the number of aortic dissection patients with severe OSA, with an AHI greater than 30/hr, was significantly larger than that of the control group 1) .…”