article archive
October 2006
Heart rate variability -- insight
into the nervous system
by Dr. Christopher Kent
The heart, the brain, and the autonomic
There is a two-way communication
system between the brain and the heart. Analysis of the beat‑to‑beat
patterns of the heart may be used to evaluate balance between
the sympathetic and parasympathetic divisions of the autonomic
nervous system. When the two branches of the autonomic system
are working together at maximum efficiency, you feel "in
sync." This is because the sympathetic and parasympathetic
divisions are not fighting one another. Such a condition
is termed "entrainment." [1]
Variability in heart
rate reflects the vagal and sympathetic function of the autonomic
nervous system, and has been used as a monitoring tool in clinical
conditions characterized by altered autonomic nervous system
function [2]. Spectral analysis of beat‑to‑beat variability is a simple,
non‑invasive technique to evaluate autonomic dysfunction
[3].
Wellness
Normative data on heart rate variability have been
collected [4,5,6]. This technology appears to hold promise
for assessing overall fitness. Gallagher et al [7] compared
age‑matched
groups with different lifestyles. These were smokers, sedentary
persons, and aerobically fit individuals. They found that
smoking and a sedentary lifestyle reduces vagal tone, whereas
enhanced bic fitness increases vagal tone. Dixon et al [8]
reported that endurance training modifies heart rate control
through neurocardiac mechanisms. In occupational health,
the effects of various stresses of the work environment of
heart patients and asymptomatic workers may be evaluated
using heart rate variability analysis [9].
Chiropractic care
Zhang and Dean [10] reported the results of
an exciting study involving 520 subjects in a single‑visit group,
and 111 subjects in a four‑week group. The purpose
of the study was to investigate the effect of chiropractic
care in a multi‑clinic setting on the balance of the
sympathetic and parasympathetic nervous system using HRV
(heart rate variability) analysis. The study demonstrated
consistent changes in HRV. The authors reported, "The
decreased heart rate and increased total power from the HRV
analysis indicated a healthy autonomic nervous system balance
after correction of vertebral subluxation."
Acquired dysautonomia is one of the three elements in the
three‑dimensional model of vertebral subluxation [11].
Skin temperature changes, reflecting alterations in vasomotor
tone, are used clinically to assess autonomic changes associated
with vertebral subluxations. Heart rate variability represents
an exciting, non‑invasive technology to assess subluxation‑related
autonomic function.
Proprietary instrumentation, developed by
CLA, is designed to control for emotional arousals, which
can contaminate HRV data collected using other systems. HRV
capability may be added to the Insight instrumentation. It
will empower the practicing chiropractor to assess and communicate
the far‑reaching impact of subluxation correction and
a healthy lifestyle.
References
1. Childre D: "One Minute Stress Management." Planetary
Publishers. Boulder Creek, CA. 1998.
2. DeDenedittis G, Cigada
M, Bianchi A, et al: "Autonomic
changes during hypnosis: a heart rate variability power spectrum
analysis as a marker of sympatho‑vagal balance." Int
J Clin Exp Hypn 1994;42(2):140.
3. Kautzner J, Camm AJ: "Clinical relevance of heart
rate variability." Clin Cardiol 1997;20(2):162.
4. O'Brien
IA, O'Hare P, Corrall RJ: "Heart rate variability
in healthy subjects: effect of age and the derivation of
normal ranges for tests of autonomic function." Br Heart
J 1986;55(4):348
5. Toyry J, Mantysaari M, Hartikainen J, Lansimies
E: "Day‑to‑day
variability of cardiac autonomic regulation parameters in
normal subjects." Clin Physiol 1995;15(1):39.
6. Sato N,
Miyake S, Akatsu J, Kumashiro M: "Power
spectral analysis of heart rate variability in healthy young
women during the normal menstrual cycle." Psychosom
Med 1995;57(4):331.
7. Gallagher D, Terenzi T, de Meersman R: "Heart rate
variability in smokers, sedentary, and aerobically fit individuals." Clin
Auton Res 1992;2(6):383.
8. Dixon EM, Kamath MV, McCartney N,
Fallen EL: "Neural
regulation of heart rate variability in endurance athletes
and sedentary controls." Cardiovasc Res 1992;26(7):713
9.
Kristal‑Boneh E, Raifel M, Froom P, Ribak J: "Heart
rate variability in health and disease." Scand J Work
Environ Health 1995;21(2):85.
10. Zhang J, Dean D: "Effect of short‑term chiropractic
care on pain and heart rate variability in a multisite clinical
Study." International Research and Philosophy Symposium:
Abstracts. Sherman College of Straight Chiropractic. Spartanburg,
SC. October 9‑10, 2004.
11. Kent C: "A three‑dimensional model of vertebral
subluxation." The Chiropractic Journal 1998;12(9):38,50.
(Dr.
Christopher Kent, president of the Council on Chiropractic
Practice, is a 1973 graduate of Palmer College of Chiropractic.
The WCA's "Chiropractic Researcher of the Year" in
1994, and recipient of that honor from the ICA in 1991, he
was also named ICA "Chiropractor of the Year" in
1998. He is director of research and a co‑founder of
Chiropractic Leadership Alliance. An attorney as well as
a chiropractor, Dr. Kent is a member of the California bar.
With Dr. Patrick Gentempo, Jr., Dr. Kent produces a monthly
audio series, "On Purpose," covering current events
in science, politics and philosophy of vital interest to
the practicing chiropractor. For subscription information
call 800‑892‑6463.)