Electrocardiogram (ECG) findings offer interesting arguments for both sides of the issue. There is a similarity in the sexes regarding the mean and standard deviation of the R-R interval portion of electrocardiogram (intervals between positive deflection of the QRS complex, which involves the depolarization of ventricular cardiac cells). On the other hand, women have been reported to have lower, similar, and higher high-frequency power (HF) and similar low-frequency power (LF) of heart rate variability (HRV). (HRV is a strong predictor of mortality adversely affected by such problems as anxiety, depression, and trauma.)
A team of researchers has speculated whether confusing findings in heart activity of the sexes could be attributed to the nonlinear characteristics of pacemaker activity, which may cause large variations when analyzed by traditional linear methods. Such variations might lead to severe interference if there are gender differences in the discharge from the heart's natural pacemaker, the sinus (SA) node. Accordingly, they set out to determine whether the complexity or chaos of cardiac pacemaker activity differs between women and men. Because aging may be a major determinate of heart rate dynamics, the researchers systemically studied the effect of aging on nonlinear properties and on gender-related differences. The results were then compared with standard frequency-domain methods to measure the nervous system's parasympathetic and sympathetic regulation of heart rate.
Contact: Donna Krupa
American Physiological Society