Patients with obstructive sleep apnea have enlarged and thickened hearts that pump less effectively, but the heart abnormalities improve with use of a device that helps patients breathe better during sleep, according to a new study in the April 4, 2006, issue of the Journal of the American College of Cardiology.
"Not only are the shape and size of the heart affected, the right side of the heart was dilated and the heart muscle on the left side was thicker in patients with obstructive sleep apnea, but the pump function was also reduced. The changes were directly related to the severity of the problem. Treating the problem brought significant improvements in the affected parameters, as well as in symptoms, in a relatively short period of time of six months," said Bharati Shivalkar, M.D., Ph.D. from the University Hospital Antwerp in Antwerp, Belgium.
Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder associated with increased risk of cardiovascular disease. The OSA syndrome is characterized by repeated partial or complete closure of the pharynx, gasping episodes, sleep fragmentation, and daytime sleepiness. Previous studies have shown that sleep apnea is associated with high blood pressure and other cardiovascular risks, including stroke, ischemia, arrhythmias, or sudden death.
This study included 43 patients (32 men and 11 women) with obstructive sleep apnea. Sleep lab studies measured the severity and frequency of complete or partial interruptions of airflow. The shape and pumping action of the participants' hearts was measured using ultrasound. The researchers also examined 40 similar control subjects who were healthy and did not report any symptoms that would indicate sleep apnea.
Compared to the control subjects, the hearts of the sleep apnea patients were significantly enlarged on the right side and had thickened walls between the pumping chambers. The hearts of sleep apnea patients also pumped less blood per beat, and the velocity of wall motion was slower for both the left and right compared to the control subjects. The sleep apnea patients also had higher blood pressure and faster heart rates than the control subjects. The severity of the heart abnormalities was correlated with the severity of obstructive sleep apnea.
The sleep apnea patients were then given continuous positive airway pressure (CPAP) devices to treat their breathing problems. An air pump that is connected by a tube to a face mask helps keep the patient's airways open during the night. CPAP is a common sleep apnea treatment that often helps patients sleep better and then remain alert during the day.
In this study, the 25 sleep apnea patients who were evaluated after six months of CPAP treatment were not only sleeping better, and were more alert during the day, but there were significant improvements in the size, shape and pumping action of their hearts.
"From a cardiovascular standpoint, OSA still remains an important under-diagnosed and under-treated problem. Our study highlights that the changes in the shape and function of the heart can be assessed quite easily in a non-invasive manner and can alert the physician of impending cardiac problems. Most importantly, treatment can cause substantial improvement in a relatively short time. We hope that this paper will contribute towards improved awareness of cardiovascular and general physicians of a fairly common problem in the western society," Dr. Shivalkar said.