Study explains why patients with OSA are at higher risk for cardiovascular disease

June 01, 2007

Researchers have found that patients with obstructive sleep apnea (OSA) have higher levels of a type of dead cells (apoptotic cells) from the lining (endothelium) of their blood vessels circulating in their bloodstream than people who do not have OSA. The finding may help explain why those with OSA are at higher risk for cardiovascular disease (CVD).

According to the researchers, "levels of apoptotic endothelial cells are correlated with abnormal endothelial vasorelaxation, a precursor of atherosclerosis-related events," and that treatment with nasal continuous positive airway pressure (nasal CPAP) can reduce levels of circulating apoptotic endothelial cells in OSA patients.

These findings appear in the June 1 issue of the American Journal of Respiratory and Critical Care Medicine, a publication of the American Thoracic Society.

Lead researcher Ali El Sohl, M.D., M.P.H., said the study was done "to explain why patients with OSA had a higher risk of cardiovascular morbidity and mortality." He added that "the increased levels of circulating apoptotic endothelial cells would mean less production of nitric oxide that is crucial to artery vasodilatation. The less nitric oxide, the higher potentially is the risk of hypertension and acute heart attack. CPAP treatment would likely restore the physiologic function of the lining of the blood vessels."

For the study, 14 men with OSA were recruited from the Sleep Clinic at the Erie County Medical Center, a hospital affiliated with the University of Buffalo, in New York. The patients were nonsmokers without any coexisting diseases, and they did not use medications. Ten healthy nonsmokers were recruited from a wellness clinic at the same hospital to serve as controls.

The OSA patients were given polysomnographic testing to verify the diagnosis. This involved evaluating brain waves, electrical activity of muscles, eye movements, breathing rates, blood pressure, blood oxygen saturation and heart rhythm, as well as direct observation of patients during sleep.

The men were comparable in age, blood pressure and metabolic profiles, but the OSA patients had a higher body-mass index, though the difference was not statistically significant. The OSA patients also had more apoptotic cells circulating in their bloodstreams and had vasomotor dysfunction.

The OSA patients were given nasal CPAP treatment for eight weeks. Use of CPAP ranged from four to seven hours per night. At the end of the study, the patients' vascular reactivity and circulating endothelial apoptotic cells were reevaluated and compared to the controls.

There were no significant differences in body measurements and metabolism in the men from baseline, but most of the patients who received CPAP had reduced circulating endothelial apoptotic cells and had marked improvements in brachial artery vascular reactivity.

The study had some limitations. Women were excluded to keep the study population homogeneous. Said Dr. El Sohl, "a follow-up study would be required to look at this phenomenon in women and in particular the hormonal effect on apoptosis in OSA." The researchers "did not perform a thorough assessment for excluding coronary disease."

More research is needed before these results can be applied clinically, according to Dr. El Sohl. While CPAP is currently used to treat OSA, looking for circulating apoptotic endothelial cells as a marker to fine-tune the therapy is one potential application. This may potentially reduce OSA patients' risk of CVD. Dr. El Sohl mentioned that statins, angiotensin converting enzyme inhibitors, and vitamin C reduce enthothelial apoptosis, but it is not known if these agents could help patients with OSA.

According to Dr. El Sohl, further research will investigate if the improvements in vascular function correlate with actual improvements in the sleep patterns of patients with OSA.
-end-


American Thoracic Society

Related Blood Pressure Articles from Brightsurf:

Children who take steroids at increased risk for diabetes, high blood pressure, blood clots
Children who take oral steroids to treat asthma or autoimmune diseases have an increased risk of diabetes, high blood pressure, and blood clots, according to Rutgers researchers.

High blood pressure treatment linked to less risk for drop in blood pressure upon standing
Treatment to lower blood pressure did not increase and may decrease the risk of extreme drops in blood pressure upon standing from a sitting position.

Changes in blood pressure control over 2 decades among US adults with high blood pressure
National survey data were used to examine how blood pressure control changed overall among U.S. adults with high blood pressure between 1999-2000 and 2017-2018 and by age, race, insurance type and access to health care.

Transient increase in blood pressure promotes some blood vessel growth
Blood vessels are the body's transportation system, carrying oxygen and nutrients to cells and whisking away waste.

Effect of reducing blood pressure medications on blood pressure control in older adults
Whether the amount of blood pressure medications taken by older adults could be reduced safely and without a significant change in short-term blood pressure control was the objective of this randomized clinical trial that included 534 adults 80 and older.

Brain blood flow sensor discovery could aid treatments for high blood pressure & dementia
A study led by researchers at UCL has discovered the mechanism that allows the brain to monitor its own blood supply, a finding in rats which may help to find new treatments for human conditions including hypertension (high blood pressure) and dementia.

Here's something that will raise your blood pressure
The apelin receptor (APJ) has been presumed to play an important role in the contraction of blood vessels involved in blood pressure regulation.

New strategy for treating high blood pressure
The key to treating blood pressure might lie in people who are 'resistant' to developing high blood pressure even when they eat high salt diets, shows new research published today in Experimental Physiology.

Arm cuff blood pressure measurements may fall short for predicting heart disease risk in some people with resistant high blood pressure
A measurement of central blood pressure in people with difficult-to-treat high blood pressure could help reduce risk of heart disease better than traditional arm cuff readings for some patients, according to preliminary research presented at the American Heart Association's Hypertension 2019 Scientific Sessions.

Heating pads may lower blood pressure in people with high blood pressure when lying down
In people with supine hypertension due to autonomic failure, a condition that increases blood pressure when lying down, overnight heat therapy significantly decreased systolic blood pressure compared to a placebo.

Read More: Blood Pressure News and Blood Pressure Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.