Obstructive sleep apnea (OSA) is a strong and independent risk factor for the development of hypertension, particularly resistant hypertension, and cardiovascular diseases. Patients with resistant hypertension have a high prevalence of OSA in association with elevated aldosterone levels, high salt intake, and salt-sensitive BP. The objective of this study was to determine whether dietary salt and aldosterone are associated with severity of OSA in patients with resistant hypertension.
Ninety-seven patients with resistant hypertension were prospectively evaluated by overnight polysomnography and 24-h urinary sodium and aldosterone levels while maintaining their usual diet. Hyperaldosteronism was defined as a plasma renin activity of < 1 ng/mL/h and urinary aldosterone level of ≥ 12 μg/24 h.
Overall, patients' mean clinic BP was 156.3 ± 22.4/88.9 ± 13.3 mm Hg while taking an average of 4.3 ± 1.1 antihypertensive medications. Prevalence of OSA was 77.3%. Twenty-eight (28.9%) patients had hyperaldosteronism. Urinary sodium level was an independent predictor of severity of OSA only in patients with hyperaldosteronism.
The findings suggest that dietary salt is related to the severity of OSA in patients with resistant hypertension and hyperaldosteronism. The results support dietary salt restriction as a treatment strategy for reduction of OSA severity in these patients.
"Aldosterone excess may play a pathophysiological role in the relation between HTN and OSA [27, 28, 33, 34]. Aldosterone assists in the regulation of circulating blood volumes and potassium concentration via a feedback loop within the adrenal cortex. "
[Show abstract][Hide abstract] ABSTRACT: Hypertension (HTN) is a modifiable, highly prevalent risk factor for cardiovascular morbidity and renal dysfunction worldwide. In the United States, HTN affects one in three adults, contributes to one out of every seven deaths and to nearly half of all cardiovascular disease-related deaths. HTN is considered resistant when the blood pressure remains above goal despite lifestyle modification and administration of three antihypertensive agents of different classes including a diuretic. Large population-based studies have suggested that obstructive sleep apnea (OSA) is a risk factor for resistant HTN. The mechanism proposed is a pattern of intermittent hypoxia associated with hyperaldosteronism, increased sympathetic tone, endothelial dysfunction, and inflammation. In this review we discuss the association between OSA and resistant HTN, the physiologic mechanisms linking OSA with resistant HTN, and the effect of continuous positive airway pressure therapy (CPAP) on blood pressure in patients with resistant HTN. While the reduction in blood pressure with CPAP is usually modest in patients with OSA, a decrease of only a few mmHg in blood pressure can significantly reduce cardiovascular risk. Patients presenting to a center specializing in management of hypertension should be screened and treated for OSA as a potentially modifiable risk factor.
International Journal of Hypertension 05/2013; 2013:193010. DOI:10.1155/2013/193010
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