FRIDAY, May 20 (HealthDay News) -- People with an implantable cardiac defibrillator and a breathing disorder that occurs during sleep are at greater risk for potentially deadly heart problems during the night, new research suggests.
An implantable cardiac defibrillator (ICD) is a device that monitors heart rhythm and corrects an abnormal heartbeat with an electrical shock. The new study revealed a significant increase in cases of ventricular tachycardia (a dangerous rapid heartbeat) and ventricular fibrillation (a severely abnormal heart rhythm) among patients with ICDs who also were diagnosed with sleep-disordered breathing.
In the study, published in the May issue of the journal HeartRhythm, researchers in Israel analyzed 45 patients with ICDs in an overnight sleep study and followed them over the course of one year.
Twenty-six of the study participants (57.8 percent) had sleep-disordered breathing, and these patients were more likely to receive what the researchers call "appropriate ICD therapy" -- a shock to correct the heart rhythm.
The risk for ventricular arrhythmias was higher between midnight and 6 a.m. among patients with sleep-disordered breathing, the results showed. The researchers concluded that patients with an ICD who experience nighttime arrhythmias should undergo screening for sleep-disordered breathing.
"Currently, there is limited data available with regard to the predictors of fatal arrhythmias in patients with an ICD," study author Dr. Tawfig Zeidan-Shwiri, of Ramban Medical Center in Haifa, Israel, said in a news release from the Heart Rhythm Society.
"Our study sought to find specific clinical data to help improve the safety and quality of life of patients living with an ICD, and the results indicate that the presence of sleep-disordered breathing should be considered in all patients with appropriate ICD therapy," Zeidan-Shwiri added. "However, more studies are needed to assess whether treatment of sleep-disordered breathing reduces the risk of appropriate ICD therapy."
The U.S. National Institutes of Health has more information on sleep-disordered breathing.
-- Mary Elizabeth Dallas
SOURCE: Heart Rhythm Society, news release, May 18, 2011
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