Original Research Manuscript Date of Submission: 01-07-2012

Date of Acceptance: 15-08-2011

Study of Impedance Cardiography (ICG ) in Hypertensive Patients

Dr. C V Parmar*, Dr. D L Prajapati, Dr. P A Gokhale, Dr. H B Mehta, Dr. C J Shah.

CardioVascular Lab., Dept. of Physiology, Govt. Medical College, Bhavnagar � 364001. Gujarat, India. Corresponding author�s E-mail: ch13sinh@yahoo.com, Mob: +919825970922

ABSTRACT Introduction - Impedance cardiography ( ICG ) is latest non � invasive technique to measure blood flow in major vessels of heart. In this technique, electrical impedance ( Z ) of any vessel is measured by passing constant current ( 4 mA ) by 2 outer surface electrodes and resistance offered by blood flow is sensed by another 2 inner voltage sensing surface electrodes. Increased blood flow during systole will offer least resistant to current & that is recorded as positive wave in a graph in the form of dZ / dt waveform. As only heart rate & blood pressure is not sufficient to access a person�s haemodynamic status, CO & other haemodynamic parameters measured by this simple technique will help further to access heart�s functional status. Hypertension is one of the major burden in the society. So if ICG is found to be useful in prognosis & treatment of HT, then we can reduce morbidity & mortality associated with HT. Objective � To measure cardiac parameters noninvasively in healthy controls & hypertensives using ICG & observe the effect of HT on different haemodynamic parameters. Materials and Methods - Study had been done in 2 age groups : 1st group comprises of 40 healthy controls & the 2nd of 80 hypertensive patients taking antihypertensive drugs for more than 6 months. It was carried out on Nivomon Series computerized software in supine position at Govt. Medical College & Hospital, Bhavnagar by applying 8 surface stic on type of electrodes. Observations / Results � Haemodynamic Parameters measured were SV, SI, CO, CI, SVR & SVRI. Systolic BP was higher in HT group despite taking anti HT drugs. SVR, SVRI were higher & CO, CI were lower in HT group as compared to controls. Also weak positive correlation was found between BSA & CO , weak negative for BSA & SVR in patients. Conclusion - So high BP was mainly due to higher SVR, & CO was low secondary to higher SVR in hypertensives. All parameters were measured effectively & with ease. Thus ICG will have diagnostic, prognostic value in hypertensive subjects and therapeutic decision making on basis of haemodynamic parameters. Introduction

Impedance Cardiography ( ICG ) is based on the

principle of Impedance Plethysmography. It is one of

the latest, simple & non � invasive technique that

measures volume changes of blood in chest, calf or any

other region of the body by sensing electrical

resistance changes in respective area. It measures

blood flow in Arteries. Occlusive Impedance

Plethysmography ( OIP ) measures blood flow in Veins.

Impedance Cardiography ( ICG ) measures blood flow

in major vessels of Cardiac region from which Stroke

Volume is obtained. This study is carried out to

measure Cardiac Parameters like Stroke volume ( SV ),

Cardiac output ( CO ) , Stroke Volume Index ( SI ),

Cardiac Index ( CI ), Systemic Vascular Resistance

(SVR) & Systemic Vascular Resistance Index ( SVRI )

in hypertensive patients.

In short about Impedance, the symbol used is � Z �.

Impedance in vague term, means Electrical Resistance.

Resistance ( R ) means according to Ohm�s law, voltage

( V ) to constant current ( I ) ratio.

R = V / I

In this technique, the ELECTRICAL IMPEDANCE of

any part of the body is measured by constant current

method & variations in the impedance are recorded as

a function of time as a Graph. Since blood is a good

conductor of electricity, the amount of blood in a given

body segment is reflected inversely in the electrical

International Journal of Pharmaceutical Sciences INT.J.PH.SCI.,May-August,2012;4(2):-1916-1927

ISSN: 0975-4725

www.ijps.in

Int.J.Ph.Sci., May-August,2012;4(2)

impedance of the body segment. Pulsatile blood

volume by heart that is systemic blood circulation

causes proportional decrease in the electrical

impedance. Variation in the electrical impedance thus

gives adequate information about the blood circulation

in any part of the body, either Heart or any other Blood

Vessels [ 16 ].

Here constant current is passed through the body

segment of interest with the help of 2 surface

electrodes.Voltage signal devloped along the current

path is sensed with the help of another pair of

electrodes. The amplitude of the signal sensed is

directly propotional to the elecrical impedance of the

body segment. Amplification & detection of this signal

gives instantaneous electrical impedance Z of the body

segment. Difference between the instantaneous

electrical impedance & initial value of electrical

impedance ( Zo ) gives variation in the impedance as a

function of time, called the ∆Z ( t ) waveform &

indicates blood volume in that particular region. First

time derivative of the impedance ( dZ / dt ) is obtained

to give the rate of change of impedance [ 16 ]. Value of

rate of change of this impedance will give us different

measured cardiac parameters for blood volume

changes in thoracic major blood vessels, especially

aorta. With the help of dZ / dt, used in Kubicek�s

equation, stroke volume can be measured [8 , 9 ].

Hypertension is the commonest cardiovascular

disorder affecting about 20% adult populations

worldwide. It is an important risk factor for

cardiovascular mortality [ 22 ]. Reports suggest that

the prevalence of hypertension is rapidly increasing in

developing countries and is one of the leading causes of

death and disability in developing countries [ 23 ].

Cardiovascular diseases are projected to cause 4.6

million deaths in India by 2020 & Hypertension has

been reported to be responsible for 57 per cent of all

stroke deaths and 24 percent of all cardiovascular

deaths in East Asians [ 24 ]. Prevalence of hypertension

has been found to increase in rural populations

undergoing modernization. Recently, a study

conducted among labour population of Gujarat

reported prevalence of hypertension to be 16.9 % as per

WHO criteria [ 25 ]. Hypertension is becoming an

important public health problem worldwide. A recent

report on the global burden of hypertension indicates

that nearly 1 billion adults ( more than a quarter of the

world�s population ) had hypertension in 2000, and

this is predicted to increase to 1.56 billion by 2025 [ 23

]. Subjects with hypertension are known to have a two-

fold higher risk of developing coronary artery disease (

CAD ), four times higher risk of congestive heart failure

and seven times higher risk of cerebrovascular disease

and stroke compared to normotensive subjects [ 26 ].

Hypertension has been identified as one of the leading

risk factors for mortality, and is ranked third as a cause

of disability adjusted life � years [ 27 ]. Existing data

suggests that the prevalence of hypertension has

remained stable or has decreased in economically

developed countries during the past decade, while it

has increased in developing countries [ 28 ].

Hypertension is one of the modifiable major risk

factors contributing to premature mortality from

cardiovascular and cerebrovascular diseases. Given the

rising prevalence of hypertension in developing

Dr. C V Parmar et al: Study of Impedance Cardiography (ICG ) in Hypertensive Patients

Int.J.Ph.Sci., May-August,2012;4(2):-1917

countries undergoing epidemiological transition like

India, increased awareness, treatment, and control of

high blood pressure are critical to the reduction of

cardiovascular disease risk and prevention of the

associated burden of illness.

Further, In ICU or emergency set up, and at OPD for

patient coming with cardiovascular complaints, only

heart rate & blood pressure is not sufficient to access a

person�s haemodynamic status [ 1 ]. CO & other

hemodynamic parameters measured by Impedance

Cardiography were found to be helpful in many ways in

such patients. Hypertension is a hemodynamic related

disorder. BP rises as the result of increased systemic

vascular resistance ( SVR ), cardiac output ( CO ), fluid

volume, or a combination of these factors [ 29, 30 ].

Consequently, antihypertensive agents lower BP by

reducing SVR, CO, fluid volume, or combinations [ 31 ].

Previous authors hypothesized that hemodynamic

information could help tailor therapy and subsequently

improve BP control [ 32 ]. Invasive procedures for

hemodynamic profiling are not warranted in outpatient

clinics, and noninvasive procedures, such as

echocardiography, are costly and operator dependent [

33 ]. Impedance cardiography ( ICG ) has emerged as a

reliable noninvasive method to measure

hemodynamics in physician offices. In a randomized,

controlled trial, ICG - guided treatment

improved BP control rates in resistant hypertension

treated by hypertension specialists [ 34 ]. Because BP,

and specifically mean arterial pressure ( MAP ), is the

product of cardiac output ( CO ) and systemic vascular

resistance ( SVR ), antihypertensive medications exert

their effects by lowering CO, SVR or both. From a

hemodynamic standpoint, the ideal treatment regimen

for Hypertension ( HT ) should lower BP while

normalizing CO and SVR. Studies have shown that

when medications appropriately target the underlying

hemodynamic abnormalities in patients with HT, BP

control will be more effective [ 35 ].

Different parameters measured in this study are :

1. Stroke Volume ( SV ) is the amount of blood

ejected by each ventricle per beat.

2. Cardiac Output ( CO ) is the amount of blood

ejected by each ventricle per minute.

3. Stroke Volume Index ( SI ) is SV per Body Surface

Area ( BSA ) .

4. Cardiac Index (CI ) is CO per BSA .

5. Vascular resistance is a term used to define the

resistance to flow that must be overcome to

push blood through the circulatory system. The

resistance offered by the peripheral circulation is

known as the systemic vascular resistance ( SVR ).

6. Systemic Vascular Resistance Index ( SVRI ) is

SVR per BSA.

Purpose of our study is to measure & then compare all

above parameters between normal subjects &

hypertensive patients, & to see, what is the effect of HT

on above mentioned parameters. Also to see whether

these all haemodynamic parameters are useful or not

for suggesting change or modification of treatment or

life style modification.

Methods

After obtaining consent from IRB (

Institutional Review Board ) � Govt. Medical College,

Bhavnagar ; We carried out this study in two groups :

1st group comprises of 40 healthy controls & the 2nd of

80 hypertensive patients taking antihypertensive drugs

for more than 6 months. Mean duration of taking anti

� HT drugs was 7.15 + 6.65 yrs . 1st group was

containing 29 healthy male & 11 healthy female

volunteers. Mean age was 60.8 + 12.9 yrs. 2nd group

was containing 51 hypertensive male & 29 hypertensive

Dr. C V Parmar et al: Study of Impedance Cardiography (ICG ) in Hypertensive Patients

Int.J.Ph.Sci., May-August,2012;4(2):-1918

female patients. Mean age was 67.57 + 10.73 yrs. Total

14 subjects were excluded due to anticipatory

tachycardia. Study was carried out in supine position

after taking anthropometric data. It was done on

Nivomon Series Product computerised software by L &

T company at Govt. Medical college, Sir T. General

hospital & Old age home, Bhavnagar. Among 8 surface

electrodes used, four were current injecting electrodes (

I1, I2, I1', I2' ) and other four were voltage - sensing

electrodes ( V1, V2, V1',V2' ). The lower thoracic voltage

- sensing electrode ( V2, V2' ) were placed at the level

of the xiphisternum on each side at anterior axillary

line and cervical sensing electrodes ( V1, V1' ) were

positioned at the base of neck. The current injecting

electrodes delivering constant current 4 mA were

placed with two ( I1, I1' ) at top of the neck 5 cm above

the cervical sensing electrodes and the others ( I2, I2 ' )

5 cm below the thoracic voltage sensing electrode.

The Nivomon instrument estimated the stroke

volume ( SV ) from the impedance signal recorded

from the inner pair of electrodes using Kubicek�s

equation [ 8 , 9 ] as,

� Stroke volume ( SV ) = k p ( L / Zo )² [ LVET (

dZ / dt ) max ]

� where k is a constant which accounts for

variation in body composition based on age,

gender, relative fat content, chest

circumference;

� L is the inter - electrode distance ;

� p is the blood specific resistivity computed

using hematocrit as [ 13.5 + ( 4.29 Hematocrit

) ].

LVET � Left Ventricular Ejection Time is measured as

shown in figure below.

Heart Rate was calculated as 60 / RR interval

in sec, Cardiac Output ( CO ) as SV multiplied by heart

rate. All calculation was done automatically by software

& final average value of SV & CO were given. SVR was

calculated as 80 * ( MAP � CVP ) / CO. CVP was taken

by default 5mmHg as it is not much variable except in

critically ill patients. Also as we enter Height & Weight

of the subject before each test, value of BSA & so that

of Cardiac Index ( CI ). Stroke Volume Index ( SI ) &

Systemic Vascular Resistance Index ( SVRI ) were

calculated by software.

The graph of SV recorded is as below in which dZ / dt

derivative value is measured from the height of the

graph, which is used in Kubicek�s equation.

Dr. C V Parmar et al: Study of Impedance Cardiography (ICG ) in Hypertensive Patients

Int.J.Ph.Sci., May-August,2012;4(2):-1919

Following is 1 of the image displayed on monitor of Nivomon, which can be printed for further future use.

Dr. C V Parmar et al: Study of Impedance Cardiography (ICG ) in Hypertensive Patients

Int.J.Ph.Sci., May-August,2012;4(2):-1920

All datas were calculated & analysed by GraphPad

InStat � [DATASET1.ISD] Statistical software. Units of

all displayed parameters are [ AGE ( yrs ), HEIGHT (

cm ), WEIGHT ( kg ), Systolic BP ( mmHg ), Diastolic

BP ( mmHg ), Zo ( ohms ), Body Surface Area ( m² ),

Pulse Rate ( bpm ), Stroke Volume ( ml / beat ), Stroke

volume Index ( ml / beat / m² ), Cardiac Output ( lit. /

min ), Cardiac Index ( lit. / min / m² ), Left

Ventricular Ejection Time ( msecs ), Systemic Vascular

Resistance ( dyne·sec / cm�5 ), Systemic Vascular

Resistance Index ( dyne·sec / cm�5 / m² ) ].

Results

Unpaired t � test was used for comparison of

parameters between 2 groups or between males &

females. Mean + SD values of parameters in both

groups, p value & significance are shown next in Table

No. 1 :

Table No. 1:

Groups → Control Hypertensive t test Statistical

Parameters

↓ ( n = 40 ) ( n = 80 )

p

value Significance

SBP 131 ± 14.12 141.15 ± 13.27 0.0003 Extreme

DBP 82.15 ± 7.85 85.25 ± 9.02 0.0558 Not quite

Zo 29.75 ±

4.67 31.14 ± 4.73 0.1299 Not

BSA 1.71 ± 0.16 1.68 ± 0.17 0.3459 Not

PR 78.55 ± 11.8 74.2 ± 13.33 0.0719 Not quite

SV 66.4 ± 14.67 62.18 ± 16.17 0.155 Not

SI 38.65 ± 7.6 36.63 ± 7.43 0.1708 Not

CO 5.3 ± 1.03 4.6 ± 1.22 0.0014 Very

CI 3.08 ± 0.46 2.76 ± 0.64 0.0022 Very

SVR 1466.25 ±

316.15

1840.76 ±

511.87

<

0.0001 Extreme

SVRI 2482.17 ±

461.03

3055.21 ±

765.44

<

0.0001 Extreme

Differences between 2 groups are also shown in the

form of following column charts.

CHART No. 1:

CHART No. 2 :

CHART No. 3 :

Following table shows comparison between males of 2

groups.

TABLE No. 2:

Groups → Control

Males

Hypertensive

Males t test Statistical

Parameters

↓

( n = 29 )

( n = 51 ) p

value Significance

SBP 129.38 ±

14.92 139.37 ± 13.46 0.0043 Very

DBP 81.65 ±

7.82 84.19 ± 9.4 0.19 Not

Zo 27.83 ±

3.93 29.77 ± 4.35 0.045 Yes

BSA 1.75 ± 0.14

1.71 ± 0.13 0.21 Not

PR 77.51 ±

12.55 73.21 ± 14.64 0.17 Not

SV 69.99 ±

15.55 65.43 ± 16.13 0.21 Not

SI 39.91 ±

8.4 37.92 ± 7.95 0.3 Not

CO 5.54 ±

1.07 4.78 ± 1.3 0.0063 Very

CI 3.15 ±

0.51 2.79 ± 0.68 0.0091 Very

SVR 1391.68 ±

305.86 1765.56 ±

532.95 0.0002 Extreme

SVRI 2409.44

± 469.44

2993.47 ±

818.44 0.0001 Extreme

Dr. C V Parmar et al: Study of Impedance Cardiography (ICG ) in Hypertensive Patients

Int.J.Ph.Sci., May-August,2012;4(2):-1921

Following table shows comparison between females of

2 groups.

TABLE No. 3:

Groups → Control

Females

Hypertensive

Females t test Statistical

Parameters

↓ ( n = 11 ) ( n = 29 )

p

value Significance

SBP 135.27 ±

11.21 144.27 ± 12.54 0.004 Yes

DBP 83.45 ±

8.15 87.1 ± 8.11 0.22 Not

Zo 34.8 ± 1.74 33.54 ± 4.47 0.2 Not

BSA 1.62 ± 0.15 1.71 ± 0.13 > 0.99 Not

PR 81.27 ±

9.51 75.93 ± 10.67 0.14 Not

SV 56.94 ±

5.09 56.46 ± 14.82 0.87 Not

SI 35.34 ±

3.35 34.38 ± 5.86 0.52 Not

CO 4.66 ± 0.55 4.3 ± 1.01 0.16 Not

CI 2.88 ± 0.19 2.7 ± 0.56 0.13 Not

SVR 1662.81 ±

263.14 1973 ± 451.25 0.011 Yes

SVRI 2673.9 ±

395.12 3163.79 ± 661.63 0.0076 Very

To see correlation between 2 parameters, correlation

coefficient r was calculated as follows.

TABLE No. 4:

BSA & → SV CO SVR

Controls + 0.47 + 0.62 - 0.52

Hypertensive + 0.69 + 0.51 - 0.45

Significanct YES YES YES

Discussion

In India, in the year 1978, the first Impedance

Plethysmograph System was developed at Electronics

Division, BARC ( Bhabha Atomic Research Centre ). It

was then taken to Department of Surgery, Seth G.S.

Medical College & K.E.M. Hospital and Department of

Medicine, Grant Medical College & J.J. Hospital,

Mumbai. It was used for the assessment of central and

peripheral blood flow in the human body [ 10 ].

In present study, we compared different cardiac

parameters between healthy controls & hypertensive

patients to see the effect of HT, & also anti �

hypertensive drugs. Table No. 1 & Chart No. 1

indicate that although there is no significant difference

for diastolic BP, systolic BP is significantly higher in

hypertensives despite taking anti � HT drugs. Further

it shows that, there is no difference for basal

impedance Zo & Body Surface Area ( BSA ). So we can

say, groups are appropriate for comparison. Also there

is no significant differences for Heart rate, SV & SI.

Table No. 1 & Chart No. 2 show that both CO & CI

were significantly lower in hypertensive group than

those of controls. Also same table & Chart No. 3

show that, SVR & SVRI were significantly higher in

hypertensive group. So we can say that BP values were

higher due to increased SVR. Looking at the mean age

& as we excluded other disease patients like Diabetecs,

smokers & alcoholics ; increased SVR could mostly be

due to atherosclerosis secondary to hyperlipidemia. As

heart has to work, has to pump blood against increased

peripheral resistance ( after load ), both CO & CI were

found lower in hypertensives. One can easily

understand this by reconsidering one of the forms of

Ohm�s law, as expressed CO = BP / SVR. The meaning

of this formula is simply the following : Any time the

long-term level of total peripheral resistance changes (

but no other functions of the circulation change ), the

cardiac output changes quantitatively in exactly the

opposite direction [ 36 ]. Any factor that decreases the

heart�s ability to pump blood causes hypoeffectivity.

Some of the factors that can do this are the following :

Coronary artery blockage, causing a � heart attack �,

Inhibition of nervous excitation of the heart,

Pathological factors that cause abnormal heart rhythm

or rate of heartbeat, Valvular heart disease, Increased

arterial pressure against which the heart must pump,

such as in hypertension, Congenital heart disease,

Myocarditis, Cardiac hypoxia, cardiac tamponade &

cardiac metabolic derangements . Anything that

interferes with venous return also can lead to

decreased cardiac output. Some of these factors are the

following : 1. Decreased blood volume. 2. Acute venous

dilation. 3. Obstruction of the large veins. 4.

Decreased tissue mass, especially decreased skeletal

Dr. C V Parmar et al: Study of Impedance Cardiography (ICG ) in Hypertensive Patients

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muscle mass. With normal aging or with prolonged

periods of physical inactivity, there is usually a

reduction in the size of the skeletal muscles. This, in

turn, decreases the total oxygen consumption and

blood flow needs of the muscles, resulting in decreases

in skeletal muscle blood flow and cardiac output.

Regardless of the cause of low cardiac output, whether

it be a peripheral factor or a cardiac factor, if ever the

cardiac output falls below that level required for

adequate nutrition of the tissues, the person is said to

suffer circulatory shock [ 36 ]. And CI is one of the

important parameter, that is used during the

management of shock.

Table No. 2 is showing comparison between males of

two groups. It stats that, SBP is significantly higher in

hypertensives. Zo is also significantly higher in them.

As Zo is mainly due to fat [ 37 ], we can say that fat

proportion is more in HT group & so itself one of the

contributing factor for causing atherosclerosis & so on.

SVR, SVRI were higher in hypertensives & so there

were low CO, CI in them. Table No. 3 is showing

comparison between females. Again SBP was higher in

hypertensives. There was no other significant

difference except that, SVR & SVRI were higher in HT

group. CO was somewhat maintained within range as

that of control group. Most of our results are consistent

with earlier almost same study [ 42 ].

Cardiac output increases approximately in proportion

to the surface area of the body [ 36 ]. Table No. 4 is

showing the same. There was significant positive r for

correlation between BSA with SV, CO in both groups.

Significant negative correlation was there for BSA with

SVR. So SVR was decreased as BSA increased.

Although r value was high in HT group for SV, it was

low for CO. It again indicates that CO was negatively

affected by increased SVR in HT group. Also SVR

decreased as BSA increased in both groups but less in

HT group supporting earlier significant higher values

of SVR in HT group.

Earlier studies [32, 38, 39, 40, 41 ] showed that,

antihypertensive drug treatment can be individualised

on the basis of haemodynamic parameters measured

by Impedance Cardiography. It also showed better

control of BP then empirical treatment. This technique

was found to be useful with better outcome &

prognosis in HT patients. With better control of not

only BP but also other haemodynamic parameters, all

complications associated with high BP like stroke,

heart attack, renal damage, retinal damage & many

others can be avoided. Guidelines applied in earlier

studies are as follows according to different mechanism

of actions of different drugs.

Where, BB indicates â blocker ; CAA, central acting

agent ; VD, vasodilator ; ACEI, angiotensin converting

enzyme inhibitor ; ARB, angiotensin receptor blocker ;

CCB, calcium channel blocker.

TFC ( Thoracic Fluid Content ) can also be

measured by Impedance cardiography as 1000 / Zo [

19 ]. So in our study, we can suggest adding or

increasing dose of mixed dilators like ACE inhibitors,

AT1 antagonists or calcium channel blockers to reduce

SVRI. And for low CI, beta blockers should be stopped

or doses should be reduced. So with the help of a

physian, long follow up study can be done in our group

to see whether BP is controlled or not & that also for

only short term or long term. An integrative project can

be done with a pharmacologist to study effect of a

particular drug or group of drugs affecting cardiac

parameters & so ultimately heart function. Clonidine

was found to reduce BP by reducing vascular resistance

& CO [ 43 ].

Dr. C V Parmar et al: Study of Impedance Cardiography (ICG ) in Hypertensive Patients

Int.J.Ph.Sci., May-August,2012;4(2):-1923

Apart from this, We can also study the effect of

physiological factors like age, sex, BSA, posture,

exercise, diurnal variation on cardiac parameters. We

can study the effect of all chronic heart diseases on CO

& others. In ICU set up, for patients of MI, LVF or

CCF, & for post cardiac surgery patients [ 4 , 12 , 20 ],

CONTINUOUS CO monitoring with this non � invasive

technique will be a great milestone. We would able to

avoid complications like infection, hemorrhage or

arrhythmia associated with invasive catheter related

CO measurement techniques like dye � dilution, fick�s

principle or thermodilution. Further it requires

minimal clothes removal. So it is comfortable on the

patient side also. As it is simple & easy non � invasive

technique with portability of instrument, a trained staff

can also take required data instead of a qualified

doctor. So it is helpful with the problem of man �

power also , particularly in our country.

As this technique mainly detects changes of blood flow

in aorta, in conditions like coarctation of aorta, its

validity is still questioned. Also increased thoracic fluid

volume may interfere with impedance signal & give

false results [ 14 ]. Echocardiography is also non �

invasive, but again it requires a qualified radiologist or

cardiologist, & continuous CO monitoring is not

possible with this [ 17 ].

So here in our study, hemodynamic parameters

measured by ICG were significantly different between

hypertensive and nonhypertensive subjects. However,

significant individual variation of hemodynamic status

may exists. Hemodynamic measurements with ICG

characterize hemodynamic status and may be helpful

in diagnostic, prognostic and therapeutic decision

making in hypertensive subjects. Thus impedance

cardiography is advantageous in many ways & can be

widely used either for research purpose or in clinical

set up.

Dr. C V Parmar et al: Study of Impedance Cardiography (ICG ) in Hypertensive Patients

Int.J.Ph.Sci., May-August,2012;4(2):-1924

Acknowledgements

We are thankful to our Dean Dr. B. D. Parmar Sir & entire

Physiology Department for their kind support. We are also

very thankful to our subjects for taking part in our study,

without whom, this study could not have been possible. We

are also very thankful to Director of Medical Education &

Research, Gandhinagar, Gujarat state for

their encouragement & financial support in the form of

research grant.

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