Heart Rate Variability Increases in Sleep Apnea

Researchers also find pattern differences between obstructive and central sleep apnea in patients with congestive heart failure

THURSDAY, Nov. 8 (HealthDay News) -- In patients with congestive heart failure, sleep-disordered breathing causes an acute increase in heart rate variability, and obstructive sleep apnea and central sleep apnea are associated with distinct patterns of heart rate variability, according to a report published in the November issue of Sleep.

Irene Szollosi, of the Alfred Hospital and Monash University in Melbourne, Australia, and colleagues performed overnight polysomnography in 21 patients with heart failure and sleep-disordered breathing. They visually identified two 10-minute segments of both sleep-disordered breathing and stable breathing, and exported the ECG signal for heart rate variability analysis.

The researchers found that the low frequency/high frequency ratio increased during sleep-disordered breathing. They also found that central sleep apnea was associated with a lower absolute low frequency than obstructive sleep apnea (2.10 versus 2.52 ms2), a lower high frequency power (1.69 versus 2.34 ms2), an increased very low frequency percentage (78.9 percent versus 60.9 percent) and a decreased high frequency percentage (6.9 percent versus 16 percent).

"These results highlight that the interpretation of increased heart rate variability cannot be generalized to indicate better autonomic control in this group of patients," the authors conclude. "Furthermore, the distinct pathophysiology of obstructive sleep apnea and central sleep apnea produce differential effects on cardiovascular activation, which become most evident when assessing the relative contribution of power in all three frequency bands."

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