Figure 6. Contribution to explained variance in arterial pressure Mayer waves from preceding heart rate and sympathetic nerve activity waves for each of 8 subjects in two conditions, basal and stimulated (i.e. heightened) sympathetic nervous outflow.

This simple model of arterial pressure Mayer wave amplitude suggests that sympathetic outflow contributes more when sympathetic activity is high. However, heart rate consistently appears to contribute much more to arterial pressure oscillations regardless of the sympathetic state (modified from Myers et al. 2001). HR, heart rate; SNA, sympathetic nerve activity.