Low frequency power of heart rate variability reflects baroreflex function, not cardiac sympathetic innervation

Abstract

Objective Power spectral analysis of heart rate variability is used clinically to assess cardiac autonomic function. High frequency power is related to respiratory sinus arrhythmia and therefore to parasympathetic cardiovagal tone. The relationship of low frequency (LF) power to cardiac sympathetic tone is less clear. We reported previously that LF power may reflect baroreflex function; however, in the previous study LF power was not adjusted for possible influences of respiration. In this study we assessed relationships of LF power, including respiration-adjusted LF power (LFa) using the ANSAR ANX 3.0 device, with cardiac sympathetic innervation and baroreflex function in chronic autonomic failure patients who either had or did not have neuroimaging evidence of cardiac sympathetic denervation. Methods Values for LF power with patients seated at baseline and during the Valsalva maneuver were compared between groups with low or normal myocardial concentrations of 6-[18F]fluorodopamine-derived radioactivity. Baroreflex-cardiovagal gain (BRS) was calculated from the slope of cardiac interbeat interval vs. systolic pressure during the Valsalva maneuver with subjects supine. Results Individual values for LF and LFa were unrelated to myocardial 6-[18F]fluorodopamine-derived radioactivity. During both sitting rest and the Valsalva maneuver the logs of LF and LFa correlated positively with the log of BRS (r=0.61, p=0.0005; r=0.47, p=0.009; r=0.69, p<0.0001; r=0.60, p=0.0006). Patients with low BRS (≤3 msec/mm Hg) had low LF and LFa regardless of the status of cardiac innervation. Conclusion LF and LFa reflect baroreflex function independently of cardiac sympathetic innervation.

Heart rate variability is related to training load variables in interval running exercises

“…Further, the LF/HF ratio has been suggested to offer a measure of sympathovagal balance (Malliani et al 1994), but this theory has conflicting arguments (Berntson et al 1997;Eckberg, 1997). A recent study of Rahman et al (2011) concluded, and replicated previous findings (Moak et al 2007), that LFP power does not reflect cardiac sympathetic tone but may reflect the ability of baroreflexes to modulate cardiac autonomic outflows. In addition, in the recent study of Ng et al (2009), -adrenergic blockade did not affect LFP during immediate recovery after exercise.…”

Comparison of Blood Pressure and Heart Rate Variability in Saunders Cervical Traction at Three Different Forces

“…The finding of decreased heart rate in group C also supports this interpretation of vagal regulation of blood pressure. A decrease in the percentage of the LF component was also found in group C, and this change reflects baroreflex modulation 17) . Hedman et al found that HF reflects the parasympathetic regulation of the heart, i.e.…”

Heart rate variability during hemodialysis in patients with chronic renal disease

“…In this context, the LF index of HRV is also considered an indicator of baroreflex function [12,20]. It was previously observed that during hemodialysis hypotensive events were associated with significant increases in LF and HF frequency domain indices and also in baroreflex function [11].…”