[Mitral valve prolapse and autonomic activity in normal women]

We examined relationships between mitral valve prolapse (MVP) and circadian rhythm of autonomic activity using spectral analysis of heart rate variability and echocardiography in 31 normal women. The heart rate variability was calculated from 24-hour ambulatory electrocardiogram by Fourier transformation. The power spectra were quantified at 0.04-0.15 Hz (low frequency power (LF) 1n (ms2)) and 0.15-0.40 Hz (high frequency power (HF) 1n (ms2)). The HF component and the ratio of LF/HF were used as indices of parasympathetic and sympathetic activity, respectively. MVP was present in 22.6%. There were no significant differences in left ventricular dimension between subjects with MVP (group MVP (+)) and subjects without MVP (group MVP(-)). Number of ventricular premature contractions in group MVP(+) tend to be higher compared with that in group MVP(-). The level of high frequency power at 0-5 am in group MVP(+) was significantly higher than that in group MVP(-), which parasympathetic activity during sleep in MVP(+) group was higher compared with that in group MVP(-). The evaluation of autonomic activity using spectral analysis of heart rate variability for 24-hour ambulatory electrocardiogram might provide useful information about the pathology of MVP.