Obstructive Sleep Apnea and Heart Disease
Human beings spend approximately one-third of their lives sleeping. The last few decades witnessed a drastic growth in the clinical and basic aspects of sleep medicine. Sleep is no longer considered a passive and homogenous state. It consists of complex brain activity, behaviour, and physiology.
Sleep breathing disorders such as sleep apnea are prevalent disorders in the adult population and are commonly associated with co-morbid conditions. Most common type of sleep breathing disorders includes obstructive sleep apnea, central sleep apnea and sleep-related hypoventilation.1
What is obstructive sleep apnea?
Obstructive sleep apnea (OSA) is a sleep-related breathing disease that is becoming more prevalent. In OSA, during sleep, the pharyngeal airway periodically narrows and becomes obstructed. During sleep, the reduction in airflow often leads to acute derangements in gas exchange, recurrent arousals, activation of the sympathetic nervous system, and disruption in normal hormone secretion.2
There are several common sleep and daytime symptoms associated with OSA. During sleep, snoring is one of the most common symptoms, and daytime symptoms include excessive sleepiness during the day, fatigue, decreased cognitive performance, morning headache, irritability, and memory loss.3,4
Despite the numerous advancements in the understanding and the pathogenesis and clinical consequences of OSA, the great majority of patients (approximately 70%–80%) remain undiagnosed.5 Sleep Apnea & Heart Disease are greatly influenced by modifiable and non-modifiable factors. Unmodifiable factors include sex, race, genetic predisposition as well as cranio-facial anatomy. On the other hand, modifiable factors include obesity, medication, smoking, nasal congestion or endocrine disorders.3
Population-based studies have shown that symptomatic OSA affects approximately 3% to 7% of adult men and 2% to 5% of adult women.1 It is found to be 1.5-2 times more common in men than in women and its prevalence increases with age and obesity. The screening for patients with suspected OSA starts with a thorough sleep history to identify symptoms, risk factors, and comorbid conditions, followed by a physical examination for OSA-related features.3
Obstructive Sleep Apnea and Heart Diseases
Studies have reported that heart disease is one of the leading causes of death in the United States and around the world. The risk of heart disease is increased by a number of factors, which include unhealthy dietary habits, lack of physical activity, excessive alcohol intake, and smoking. hypertension, unhealthy cholesterol levels, diabetes and obesity. Sleep breathing disorders, particularly OSA also significantly increases the risk of heart arrhythmias and cardiovascular disease. It has been reported that patients with sleep apnea are 2-4 four times more likely to develop heart arrhythmias (abnormal heart rhythms) than people without this condition. Sleep apnea increases the risk of heart failure by 140% and the risk of coronary heart disease by 30%.6 Several epidemiological and clinical studies have explored the association between OSA and heart disease as they share common risk factors such as age, gender, race and obesity.
Sleep Apnea, Obesity and Heart Disease
Obesity is counted as one of the most common risk factors for the development of OSA as well as heart diseases. It is often associated with increased fat around the neck that narrows or blocks the upper airway while sleeping. It is crucial to remember that sleep apnea, whether alone or in combination with obesity, can raise the risk of heart disease. But an increase in 10% body weight accounts for the increase in the risk of OSA six-fold. Sleep apnea alone or with obesity increases the risk of heart diseases like high blood pressure, an increase in bad cholesterol levels, and diabetes.
Insufficient Sleep and heart health
Allowing the body to rest and reenergize is one of the most significant purposes of sleep. During sleep, your heart rate and blood pressure both decrease. Insufficient or fragmented sleep in conditions like OSA can negatively affect heart health by not providing proper time for rest and recovery. Chronic sleep deprivation poses an increased risk for hypertension, heart attack and stroke.7
Effects of OSA on the cardiovascular system
The recurrent pauses in breathing during an episode of sleep apnea can stress and damage not only the heart but also the complete cardiovascular system. The negative impact of sleep apnea on the heart is still ongoing research, however, several biological pathways have been suggested as linking sleep apnea to cardiovascular diseases. The pathways include:
Activation of sympathetic nervous system
In OSA, repetitive cessation of breathing during sleep causes decreased oxygen levels in the blood, which leads to the activation of specialized cells called chemoreceptors. These cells detect the changes and elevate the activity of the sympathetic nervous system, the part of the nervous system that responds to stress and anxiety. This triggers the body to gasp more air and wakefulness. Similarly, the sympathetic nervous reacts to lower oxygen levels by constricting blood vessels and increasing heart rate and blood pressure. Recurrent episodes of obstructive apnea throughout the sleep could cause repetitive changes in blood pressure and may lead to hypertension or can worsen the existing cardiovascular conditions. In patients, with moderate to severe OSA, it can lead to a 25% rise in systolic and diastolic pressure.6
Intra-thoracic pressure changes
Inhalation occurs against a restricted or closed upper airway in people with OSA. These attempted forceful inhalations might result in significant changes in chest cavity pressure. The heart can be damaged by these repeated variations in intrathoracic pressure, which can lead to atrial fibrillation (an irregular, typically rapid heartbeat), blood flow difficulties, and even heart failure.
After each pause in breath, a lack of oxygen causes the formation of oxygen reactive species, during the phase of reoxygenation. This leads to an increase in oxidative stress, which promotes systemic inflammation along with neurochemical and physiological processes that raise the risk of heart disease.6,8
Management of OSA to reduce risk of heart diseases
If a person is diagnosed with OSA, treatments are often effective and help in reducing the risk of heart disease. Management of OSA includes:
Maintaining a healthy weight: Obesity is considered one of the causes of OSA as well as cardiovascular diseases. Maintaining a healthy weight can help in the management of OSA and in decreasing the risk of heart disease.
Lifestyle modifications: Regular exercise can help in increasing respiratory strength and helps in increasing the flow to the lungs. Avoiding alcohol intake in the evenings can also help in reducing the symptoms of OSA during sleep and improve daytime functions.
Positive pressure therapies: Continuous positive air pressure (CPAP) devices keep the upper airway from collapsing during sleep.
Surgery: In patients whose OSA is caused solely by anatomical compromise of the upper airway, surgical intervention may be considered, although it is rarely performed in adult patients.
Oral appliances: Customised dental or oral appliances are used to retain protruding jaw and to reposit or stabilize the tongue while sleeping to prevent upper airway obstruction.
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- J. Lin, M. Suurna, “Sleep Apnea and Sleep-Disordered Breathing,” Otolaryngol Clin North Am. 2018;51(4):827-833. doi: 10.1016/j.otc.2018.03.009.
- F. Ralls , L. Cutchen, “A contemporary review of obstructive sleep apnea,” Curr Opin Pulm Med. 2019;25(6):578-593. doi: 10.1097/MCP.0000000000000623.
- J.V. Rundo, “Obstructive sleep apnea basics,” Cleve Clin J Med. 2019;86(9 Suppl 1):2-9. doi:10.3949/ccjm.86.s1.02
- A.M. Osman, S.G. Carter, J.C. Carberry, D.J. Eckert, “Obstructive sleep apnea: current perspectives,” Nat Sci Sleep. 2018;10:21-34. Published 2018 Jan 23. doi:10.2147/NSS.S124657
- H.K. Yaggi, K.P. Strohl, “Adult obstructive sleep apnea/hypopnea syndrome: definitions, risk factors, and pathogenesism,” Clin Chest Med. 2010;31(2):179-86. doi: 10.1016/j.ccm.2010.02.011.
- G. Jean-Louis, F. Zizi, D. Brown, G. Ogedegbe, J. Borer, S. McFarlane, “Obstructive sleep apnea and cardiovascular disease: evidence and underlying mechanisms,” Minerva Pneumol. 2009;48(4):277-293.
- M.A. Grandner, P. Alfonso-Miller, J. Fernandez-Mendoza, S. Shetty, S. Shenoy, D. Combs, “Sleep: important considerations for the prevention of cardiovascular disease,” Curr Opin Cardiol. 2016;31(5):551-565. doi:10.1097/HCO.0000000000000324
- L. Lavie ,“Obstructive sleep apnoea syndrome–an oxidative stress disorder,” Sleep Med Rev. 2003;7(1):35-51. doi:10.1053/smrv.2002.0261
|25th January 2022