Am J Cardiol. 1992 Jan 15;69(3):201-5.  

Spectral analysis of heart rate dynamics in elderly persons with postprandial
hypotension.

Ryan SM, Goldberger AL, Ruthazer R, Mietus J, Lipsitz LA.

Department of Medicine, Beth Israel Hospital, Boston, Massachusetts.

Prior studies suggest that postprandial hypotension in elderly persons may be
due to defective sympathetic nervous system activation. We examined autonomic
control of heart rate (HR) after a meal using spectral analysis of HR data in 13
old (89 +/- 6 years) and 7 young (24 +/- 4 years) subjects. Total spectral
power, an index of overall HR variability, was calculated for the frequency band
between 0.01 and 0.40 Hz. Relatively low-frequency power, associated with
sympathetic nervous system and baroreflex activation, was calculated for the
0.01 to 0.15 Hz band. High-frequency power, representing parasympathetic
influences on HR, was calculated for the 0.15 to 0.40 Hz band. Mean arterial
blood pressure declined 27 +/- 8 mm Hg by 60 minutes after the meal in elderly
subjects, compared with 9 +/- 8 mm Hg in young subjects (p less than or equal to
0.0001, young vs old). The mean change in low-frequency HR power from 30 to 50
minutes after the meal was +19.4 +/- 25.3 U in young subjects versus -0.1 +/-
1.5 U in old subjects (p less than or equal to 0.02). Mean change in total power
was also greater in young (19.0 +/- 26.6 U) subjects compared with old subjects
(0.0 +/- 1.6 U, p greater than or equal to 0.02). Mean ratio of
low:high-frequency power increased 3.1 +/- 3.3 U in young subjects vs 0.5 +/-
2.7 U in old subjects (p less than or equal to 0.01). The increase in
low-frequency HR power and in the low:high frequency band ratio in young
subjects is consistent with sympathetic activation in the postprandial
period.(ABSTRACT TRUNCATED AT 250 WORDS)

PMID: 1731460 [PubMed - indexed for MEDLINE]