A Close Examination of the Use of Systolic Time Intervals in the Calculation of Impedance Derived Cardiac Autonomic Balance and Regulation

Traditionally, impedance derived measures of cardiac autonomic balance (CAB) and regulation (CAR) are calculated using indices heart rate variability (HRV) that primarily reflect parasympathetic nervous system activity (e.g., high-frequency HRV | HF-HRV) pre-ejection period (PEP; a systolic time interval measure sympathetic activity). However, HF-HRV PEP considered chronotropic inotropic influence, respectively. Left ventricular ejection (LVET) is reflects therefore may be more appropriate for calculating CAB CAR compared to PEP. Thus, the current study evaluates both LVET in calculation CAR. Data from 158 healthy participants (mean age = 19.09 years old, SD 1.84 years) were available analyses. values root mean square successive differences, addition LVET, accordance with previously established guidelines. Analyses showed correlations significantly weaker between HF ( z 5.12, p < 0.001) RMSSD 5.26, than These data suggest PEP, provides better “autonomic space” as evidenced by lack correlation computed LVET. We stress future research consider activity, doing so yield accurate independent mixture (i.e., PEP) measures.