title: Spectral analysis of heart rate dynamics in elderly persons with postprandial hypotension.
abstract: 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)
authors.affiliation: Department of Medicine, Beth Israel Hospital, Boston, Massachusetts.
authors.forename: S M
authors.initials: SM
authors.lastname: Ryan
authors.forename: A L
authors.initials: AL
authors.lastname: Goldberger
authors.forename: R
authors.initials: R
authors.lastname: Ruthazer
authors.forename: J
authors.initials: J
authors.lastname: Mietus
authors.forename: L A
authors.initials: LA
authors.lastname: Lipsitz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D001794:Blood Pressure; D004435:Eating / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007022:Hypotension / Q000503:physiopathology*; D008297:Male; D011311:Pressoreceptors / Q000503:physiopathology*; D013057:Spectrum Analysis; D013997:Time Factors