In a study published in Hypertension, a journal of the American Heart Association, researchers from the University of Sao Paulo Medical School found that Obstructive Sleep Apnea (OSA), a sleep disorder that affects 12 million American adults, is an independent risk factor for the development of atherosclerosis or hardening of arteries. Hence individuals suffering from OSA have an increased risk for stroke, heart attack and peripheral vascular disease.
Obstructive Sleep Apnea (OSA) is a sleep disorder in which complete or partial obstruction of the airway during sleep causes oxygen desaturation and frequent arousals from sleep. The sleep of the person suffering from OSA is characterized by episodes of apnea and hypopnea. Apnea is the complete cessation of the airflow for greater than 10 seconds. As a result, affected persons have lethargy, nighttime snoring and excessive daytime sleepiness. The disorder is associated with hypertension, impotence, obesity and emotional problems. Sleep apnea is more common in men. One out of 25 middle-aged men and 1 out of 50 middle-aged women have sleep apnea. Sleep apnea becomes more common as you get older. At least 1 out of 10 people over the age of 65 has sleep apnea. Also if someone in your family has sleep apnea, you're more likely to develop it
Atherosclerosis is a disease in which plaque made up of fat, cholesterol, calcium, and other materials builds up on the inner lining of the arteries. Atherosclerosis results in the gradual occlusion of the arterial wall resulting in chronic ischemia to tissues or acute events like the heart attack and stroke. Several factors have been found to be risk factors for the formation of the atherosclerosis including hypertension, high lipids, obesity, diabetes, smoking, age, lack of physical activity, family history etc. Atherosclerosis is the primary pathology in several diseases including stroke, myocardial infarction and peripheral vascular disease.
The researchers believe that the OSA may contribute to the atherosclerosis development through several mechanisms including systemic inflammation, oxidative stress, vascular smooth muscle activation and endothelial dysfunction.
The study was conducted among 94 middle aged non-diabetic non-smokers. The study participants underwent a sleep study called polysomnography to determine the apnea-hypopnea index to evaluate the severity of the OSA. Polysomnography is considered as the gold standard for the diagnosis of OSA. The carotid intima-media thickness, carotid diameter and distensibility of the study population were measured. Increased carotid intima-media thickness is considered as a marker for atherosclerosis. The participants with both OSA and hypertension had maximal thickness of the intima-media suggesting that OSA and hypertension have additive effects on the carotid atherosclerosis.
Earlier in a different study, it was found that even apparently healthy young individuals with OSA have early biomarkers for atherosclerosis. It is also documented that treatment of the OSA with the continuous positive pressure ventilation decreased the carotid intima-media thickness, an early predictor for atherosclerosis. Also contributing to the risk of cardiovascular events in the patient with OSA is the increased prevalence of hypertension. Upto 40% of patients suffering from OSA have increased blood pressure.
The findings underscore the necessity of proper management of the OSA. Currently OSA is managed with a combination of life style changes, mouth pieces, breathing devices and if necessary surgery. Life style changes include avoiding alcohol, reducing weight, proper exercises etc. For moderate sleep apnea, continuous positive airway pressure is recommended. People with severe symptoms of apnea feel better after using the continuous positive airway pressure. Surgery is sometimes indicated to widen the airway passages.
Furthermore all patients with hypertension and sleep disturbances may be evaluated for obstructive sleep apnea.
Reference: Hypertension 2009;53;64-69; Luciano F. Drager, Luiz A. Bortolotto, Eduardo M. Krieger and Geraldo, Lorenzi-Filho; Additive Effects of Obstructive Sleep Apnea and Hypertension on Early Markers of Carotid Atherosclerosis
