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ISSN 2348-313X (Print)
International Journal of Life Sciences Research ISSN 2348-3148 (online)
Vol
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researchpublish
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S
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Singh3
1

Tutor/Demonstrator, 2Tutor/Demonstrator, 3Professor, Department of Physiology, Narayana Medical College, Nellore,
Andhra Pradesh, India

Abstract: To study the variations of autonomic nervous system in hypertensive patients using a set of autonomic
function tests
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These results were compared with age and sex matched controls (normotensives)
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Hypertensives show abnormal values on autonomic
function testing, when compared with normotensives
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The results were obtained using ANOVA and
student‘t’ –test, to study the significance of autonomic parameters
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Valsalva ratio & Heart rate response to deep breathing test values
were decreased in Hypertensives as compared to Normotensives (p<0
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S: L ratio also decreased, and the
decrease was statistically significant (p<0
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Isometric handgrip exercise and cold pressor tests shows that there
was significant rise in the systolic and diastolic blood pressure in Hypertensives as compared to Normotensives
increase was statistically significant (p<0
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From this study, it is evident that Hypertension can alter the normal
autonomic functions of the body and predisposes to autonomic neuropathy
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Keywords: Autonomic nervous system, Hypertension, Blood Pressure, Valsalva ratio, Deep Breathing Test, Cold
pressor test
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INTRODUCTION

The autonomic nervous system plays a crucial role in blood pressure (BP) and heart rate (HR) control and may thus be an
important pathophysiological factor in the development of hypertension
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if left untreated
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Hypertension is defined as a sustained elevation of systemic arterial blood pressure
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It can be
produced secondary to many diseases or more commonly without any cause
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The major complications of hypertension are: Excess work load on the heart leads to heart failure and coronary heart
disease, often leads to death due to heart attack, High pressure damages a major blood vessels in brain, it is a cerebral
infarct clinically it is called stroke
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The Autonomic Nervous System regulates the 'automatic' functions of the body such as blood pressure, heart rate,
breathing, stomach and intestinal function, and bladder function
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Disorders of the autonomic nervous system can be identified through autonomic function testing
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2, Issue 4, pp: (43-47), Month: October - December 2014, Available at: www
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For these tests a person will be attached to a blood pressure machine which monitors the blood pressure continuously and
an electrocardiograph which monitors the heart rhythm continuously
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II
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The approval of
Department of Cardiology and Medical ethics committee of Narayana Medical College, Nellore was taken for this “Study
of Autonomic function tests in Hypertensives”
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The procedure was explained and written consent was obtained from the subjects
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The subject selection was
based on the predetermines exclusion-inclusion criteria
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2, Issue 4, pp: (43-47), Month: October - December 2014, Available at: www
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Patients where it was technically difficult to perform echocardiography
Abnormal Cardiovascular and Respiratory system on clinical examination
The autonomic function tests studied were:
I
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Subject was instructed to maintain deep
breathing at a rate of six breaths per minute and was made to lie down comfortably in supine position with head elevated
to 300
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While subject was breathing deeply at a rate of 6
breaths per minute (allowing 5 seconds each for inspiration and expiration) maximum and minimum heart rates were
recorded with each respiratory cycle
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II
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Subject was
made to lie down in a semi recumbent or sitting position
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Mouth piece was put into the
mouth of the subject and the Mercury manometer was connected to the mouth piece
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Subject was asked to exhale forcefully into the mercury manometer and asked to maintain the
expiratory pressure at 40 mm of Hg for 10 – 15 seconds
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Valsalva ratio were calculated by using the formula
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Cold Pressor test (cold pressure test): Subject was instructed regarding the test
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Cold water was taken in a container
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Blood pressure was recorded at the end of 60 seconds of submersion of the limb
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IV
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This response is detected by recording ECG in supine and standing postures
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ECG electrodes were connected from the subject to the cardiowin system
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Basal heart rate was recorded by using cardiowin
system
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Heart rate response to standing was determined by using the formula heart rate in standing position – heart rate
in supine position
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Hand Grip Test: In the hand grip test, there is a rise in heart rate and blood pressure
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Subject was made to lie
down in semi recumbent position
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Basal heart rate and blood pressure were recorded
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Heart rate and change in
SBP, DBP were recorded
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The S: L (standing to lying) ratio was taken as the ratio of the longest R-R interval during the 5 beats before lying
down to the shortest R-R interval during the 10 beats in the ECG after lying down
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2, Issue 4, pp: (43-47), Month: October - December 2014, Available at: www
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III
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0 using an unpaired„t‟ test
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1: Anthropometric variables

Variables

Hypertensives

Normotensives

Age(yrs)

39
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4

39
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8

Weight(kgs)

76
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9

68
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3

Blood Pressure(mm of Hg)

SBP-159
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2
DBP-100
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2

SBP-124
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2
DBP-78
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2

Table
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667

13
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05

S:L (standing to lying)ratio

1
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02

1
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03

<0
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45±0
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65±0
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05

Heart rate response to deep breathing(HRDB)

16
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11

23
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31

<0
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3: Statistical analysis of sympathetic function tests in Group I and Group II

Variables

Hypertensives

Normotensives

P value

Isometric Handgrip SBP

12
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2

8
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3

<0
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1±1
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1±1
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05

Cold Pressor Test SBP

12
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6

8
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4

<0
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1±1
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1±1
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05

Data presented in Table 2 shows that there was significant increase in the Heart rate response to standing
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05)
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05)
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05) and the increase was statistically significant (p<0
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IV
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This decreased
parasympathetic activity leads to decreased heart rate variability with respiration, which is reflected in our study as
decreased E: I and Valsalva ratio values in Hypertensives
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The results for the above mentioned tests are statistically significant
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As a
result venous return, cardiac output and arterial BP decreases
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This in turn leads to increased sympathetic discharge, decreased vagal tone and an
instantaneous increase in HR
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This finding
indicates possible dysfunction of sympathetic and parasympathetic component of autonomic nervous system
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al
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2, Issue 4, pp: (43-47), Month: October - December 2014, Available at: www
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There was an increase of blood pressure response to cold pressor test in the hypertensives in contrast to the control group
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An increase in the blood pressure after the cold water immersion points towards
sympathetic hyperactivity in hypertensives
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In
our study there is significant rise in both systolic blood pressure and diastolic blood pressure in hypertensive group
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Generally, Cold pressor test is largely related to great sympathetic efferent discharge causing
arterial vasoconstriction
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The findings in our study correlated with
the study conducted by Benetos A
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et
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Isometric exercise produces a significant increase in blood pressure and heart rate, a response which can easily be elicited
by using sustained hand grip
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An increase in heart rate in response to
handgrip is due to impulses from the Limbic cortex, motor cortex and the proprioceptors within small hand joints acting
as afferent inputs into the medullary cardiac centres causing inhibition of cardiac inhibitory centre, decrease in vagal tone
and increase in heart rate
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The findings in our study correlated with the study
conducted by S
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Chrysant et
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ACKNOWLEDGEMENT
The authors are thankful to Dr
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Phani Krishna, Department of Cardiology for his help in sending the subjects
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Conflict of Interest: Nil

V
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So, if this dysfunction is diagnosed early by doing various autonomic function tests,
it will be of great help in identification of those which are prone to risk of various cardiovascular complications
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Frank Weise, Dominique laude
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3, page- 303-310 (1993)
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G
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Pal, Pravatipal, “Text book of practical physiology”, 2006, pg 748-759
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Hypertension 1987; 9; 429-436
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c “Text book of medical physiology” 11 th edition 2006
B
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C
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Michael Swash, “Hutchison‟s clinical methods”, Twentieth edition, 2000
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Chrysant SG, “The value of Hand grip test as an index of autonomic function in hypertension”, Clin cardiol,
February 1982; 5(2), Pg 139-43
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al
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1984 Feb; 3(2 Pt 1):381-6
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, Am J Hypertens 1991, 4, 627-629
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W
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S
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