Study: Obstructive Sleep Apnea Puts Strain on Heart

April 26, 2021
Jill Murphy, Associate Editor

Nocturnal respiratory events, when they either completely or partially block the airways, often cause repeated oxygen desaturations and interrupted sleep in patients with OSA, leading to abnormal nervous system function.

New research from the University of Eastern Finland has found that longer nocturnal respiratory events in patients with obstructive sleep apnea (OSA) that cause higher immediate heart rate variability and greater changes in beat-to-beat intervals are associated with reduced daytime alertness, according to a press release.

Nocturnal respiratory events, when they either completely or partially block the airways, often cause repeated oxygen desaturations and interrupted sleep in patients with OSA, leading to abnormal nervous system function.

Since abnormal hyperactivation of the sympathetic nervous system affects heart function and cardiovascular regulation by increasing OSA patients’ nocturnal heart rate, it can prevent patients from getting enough deep, restorative sleep, whereas regular hyperactivation can keep the body in a state of alertness over the long term despite sufficient deep sleep, according to the study.

Two recent studies from the University of Eastern Finland have explored the immediate effect of respiratory events on heart rate variability, such as the association of nocturnal heart rate changes with the alertness of patients with OSA.

The first study shows that the type and duration of individual respiratory events has an effect on heart rate variability both during and after the event. Further, a longer duration of a respiratory event caused greater changes in heart rate as well as a higher ultra-short-term heart rate variability, and both of these changes were greater during complete obstruction of the airway, according to the current study.

"The study sheds important new light on the cardiovascular load nocturnal respiratory events cause in patients with OSA," said the study's lead author early-stage researcher Salla Hietakoste, from the University of Eastern Finland, in the press release.

The second study found that changes in pulse rate measured via finger photoplethysmogram were associated with performance in the psychomotor vigilance task (PVT) in patients with OSA. In addition, patients who performed poorly in the PVT had a significantly higher nocturnal heart rate.

"By taking a better look at polysomnography data for respiratory events and heart function, we might be able to identify patients who have a higher risk for reduced vigilance and alertness," said postdoctoral researcher Samu Kainulainen, from the University of Eastern Finland, in the press release.

In both studies, the findings were more pronounced in men, with the findings suggesting that the abundance of data available from current clinical sleep studies could be utilized more extensively in the future, according to the authors. The data relating to heart rate and heart rate variability could possibly be used alongside the current diagnostic parameters for OSA in order to get a more representative clinical picture and to better identify high-risk patients, the researchers concluded.

REFERENCE

Obstructive sleep apnea puts a strain on the heart, too. EurekAlert! Published December 10, 2020. Accessed April 21, 2021. https://www.eurekalert.org/pub_releases/2020-12/uoef-osa121020.php