Click on image to view larger version.

Figure 2 Depressed high-frequency heart rate variability (HRV) during elevated mental activities before ischemic events. High frequency (hf) HRV was significantly depressed during high levels of mental activity compared with events occurring at low mental activity. The difference emerged 10 min before the ischemic event (p = 0.060) and persisted until 4 min (p = 0.038) and 2 min before ischemia (p = 0.045). Heart rates (HR) tended to be elevated during high mental stress at onset of ischemia and 10 min before ischemia. *p < 0.05; p < 0.10 (unadjusted p values for high versus low mental activity comparisons). Solid circle = high mental activity; open circle = low mental activity.