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Correlation between carotid intima media thickness and newly diagnosed hypertensive patients.

INTRODUCTION: Hypertension is one of the leading causes of the global burden of disease. Hypertension doubles the risk of cardiovascular diseases, including coronary heart disease (CHD), congestive heart failure (CHF), ischemic and hemorrhagic stroke, renal failure, and peripheral arterial disease. (1) In children and adolescents, hypertension generally is defined as systolic and/or diastolic blood pressure consistently >95th percentile for age, sex, and height. Blood pressures between the 90th and 95thpercentiles are considered pre-hypertensive and are an indication for lifestyle interventions.

Intima-media thickness (IMT), also called intimal medial thickness, is a measurement of the thickness of tunica intima and tunica media, the innermost two layers of the wall of an artery. (2) Recently, carotid artery intima media thickness (cIMT), as measured by vascular ultrasound, has emerged as a potential marker of hypertensive vascular damage. Carotid artery IMT exhibits less variability, is associated with cardiovascular risk, and increased levels can predict myocardial infarction and stroke. (3,4,5,6) In vitro and in vivo studies showed that carotid artery IMT measurements obtained by ultrasound correlated very well with pathologic measurements. (7) IMT measurement should be included as a diagnostic tool in ultrasound, given the paucity of facilities for invasive techniques in India.

AIMS AND OBJECTIVES: To study the carotid intima media thickness in newly diagnosed hypertensive subjects and to correlate degree of hypertension with carotid intima media thickness.

MATERIALS AND METHODS: Newly diagnosed hypertensive subjects were recruited from the Internal Medicine Outpatient Department or wards of Silchar Medical College and Hospital from December 2014 to September 2015.

Hypertension was defined as 2 office BP readings revealing systolic blood pressure of >140 mmHg and/or diastolic blood pressure of >90mmHg. Patients of age >18 years with newly diagnosed hypertension were included in the study. Patients who are known hypertensive and on antihypertensive medication, patients with known chronic kidney disease, diabetes mellitus and metabolic syndrome, pregnancy induced hypertension, patients on any drugs affecting carotid IMT like beta blockers or lipid lowering agents, alcoholism were excluded from the study. All patients underwent thorough physical examinations and routine investigations. Control and hypertensive subjects were matched pair wise for gender, age ([+ or -]1 year) and BMI ([+ or -]10%). Control subjects were required to have 2 office BP readings with systolic and diastolic BP <120/80. Control subjects were taken mostly from our departmental persons, who are not having any known CVS disease. All of the participants gave informed, written consent.

CAROTID ULTRASONOGRAPHY TECHNIQUE: Carotid IMT was determined in both hypertensive and control subjects using a linear transducer (712MHz) on the PHILIPS HD 11XE machine. On longitudinal 2D ultrasound images of the carotid artery, the near and far arterial walls are displayed as 2 echogenic lines, the adventitia and intima, separated by the hypoechoic media. The distance between the leading edge of the first bright line on the far wall (Lumen-intima interface) and the leading edge of the second bright line (Media-adventitia interface) indicates the IMT. Measurements of the far wall were made 1 cm proximal to the bifurcation of the left and right common carotid artery, with the subject's head turned toward the opposite side by 45 degrees.

Average of the two measurements was taken in order to define the cIMT for each subject.

Statistical analysis was performed using SPSS 21 software.

RESULTS: Fifty two patients with essential hypertension had their cIMT measured and equal numbers of normotensive controls were matched to the hypertensive subjects with respect to age, sex and BMI. The cases were taken according to the inclusion and exclusion criteria already stated. Of the 52 hypertensive subjects, 1 had isolated diastolic hypertension, 38 had isolated systolic hypertension (ISH), and 13 had combined systolic and diastolic hypertension. The mean age of the hypertensive patients were 42.8 years (Min: 20yrs, max: 66yrs) and a mean systolic BP of 153.1mm of Hg (Min: 130mm, Max: 180mm) and a diastolic BP of 87.9mm of Hg (Min: 80mm, Max: 110mm). The mean cimt of the hypertensive group is 0.63mm (Min: 0.4mm, max: 1.2mm).Table 1 shows the demographic characteristics and for hypertensive and normotensive. Table 2 shows a comparison of office BP and cIMT of the 2 study groups. As seen, cIMT was significantly increased in the hypertensive group as compared to normotensive.

Fig. 2: Pie diagram showing blood pressure distribution: For all of the subjects combined (n=104), cIMT correlated with office systolic blood pressure (SBP) (r=0.48; p<0.001) but no correlation was found between diastolic blood pressure and cIMT (r=0.15, p=0.11). Among hypertensive subjects (n=52), there was a significant positive correlation between cIMT and SBP (r=0.59, p<0.001), as shown in figure 10. In contrast to SBP, DBP correlated insignificantly with cIMT (r=0.202; p=0.15) in the hypertensive subjects.

Fig. 10: Relationship between cIMT and office systolic blood pressure among the hypertensive cases (n=52). The figure shows a positive correlation between cIMT plotted on Y axis and systolic blood pressure plotted on X axis (r=0.59, p<0.001).

DISCUSSION: Hypertension is one of the leading causes of morbidity and mortality and its prevalence has been increasing with change in dietary patterns and lifestyle. It often is associated with additional cardiovascular disease risk factors, and the risk of cardiovascular disease increases with the total burden of risk factors. Hypertension leads to vascular damage and atherosclerosis. Various noninvasive markers of early arterial wall alteration are currently available such as arterial wall thickening and stiffening, endothelial dysfunction and coronary artery calcification. (8) Of them, Intima media thickness (IMT) of large artery walls, especially carotid can be assessed by B-Mode ultrasound in a relatively simple way and represents a safe, inexpensive, precise and reproducible measure. (9)

In clinical practice the measurement of IMT is not yet done as a routine investigation but the predictive value of IMT with regards to cardiovascular complications has been established in several prospective studies and suggests that IMT measurement might help in the future in the stratification of cardiovascular risk of asymptomatic patients in primary prevention. (10)

The present study has been undertaken to find out the correlation between hypertension and cIMT. Only the newly diagnosed hypertensive cases were selected to eliminate the possible confounding factors.

In the present study the hypertensives showed an increased carotid artery intima media thickness as compared to the normotensives. Our mean value of carotid artery intima media thickness was 0.66[+ or -]0.18mm with minimum value of 0.3mm to maximum of 1.5mm. The results are comparable to those of Matsumoto et al (2002) who observed that IMT correlated strongly with systolic blood pressure. (11)

REN Hong-kun et al described that hypertension has an important role in inducing carotid artery stenosis. It is more significant that decreased blood pressure can slow down the process of atherosclerosis. (12) Jadav and Kadam noted increased intima media thickness in hypertension which is very well correlated with our study. (13) Fuelsdi et al noticed increased carotid artery atherosclerosis and stenosis in relation to increased duration of hypertension. (14) Kablak-Ziembicka et al concluded that IMT increases with advancing CAD, patients with mean IMT over 1.15mm have a 94% likelihood of having CAD. (15)

In contrast to western studies, the mean cIMT value observed was comparatively lower in our patients. This may be probably due to lower BMI in our study population. Further, difference in genetic, racial, geographic, cultural and dietary patterns among these different study populations may influence cIMT. (16,17,18)

Marc B et al concluded that SBP correlated better with increased cIMT as compared to DBP in western children and adolescents. This is similar to our study, where cIMT correlated with SBP better. (19) There was no significant correlation between DBP and cIMT in our study which is not comparable to Khalil A et al who reported that IMT was independently and positively related to DBP. (20) In the present study it was observed that cIMT increased with increase in BMI, but there was no definite correlation between BMI and cIMT. This may be probably due to the fact that this study is limited by the number and selection of patients. Our study is comparable with that of Reed and Dwyer et al who concluded that abdominal obesity is not an independent predictor of carotid artery IMT. (21) In our study no significant correlation was found between smoking and cIMT, probably due to very less number of cases.

Our study clearly demonstrates that Intima-media thickness of common carotid arteries is significantly higher in hypertensive as compared to normal individuals. Given the already established relationship between the involvement of coronary artery and the carotid artery, early detection of the increased carotid intima media thickness in high risk individuals will prevent the development of vascular complications in hypertensive in the long run. This may make a huge difference in the lives of these patients and ultimately help them to lead a healthy life, which is the goal of all medical diagnosis and intervention.

DOI: 10.14260/jemds/2015/1879

REFERENCES:

(1.) Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL, et al. Hypertensive vascular disease. Harrison's principles of internal medicine. 18th edition, McGraw Hill; 2012; 2042-2047.

(2.) Internet source http: //en.wikipedia.org/wiki/Intima-media_thickness.

(3.) O'Leary DH, Polak JF, Kronmal RA, Savage PJ, Borhani NO, Kittner, et al. Thickening of the carotid wal. A marker for atherosclerosis in the elderly? Cardiovascular Health Study Collaborative Research Group. Stroke. 1996 Feb; 27(2): 224-31.

(4.) O'Leary DH, Polak JF, Kronmal RA, Manolio TA, Burke GL, Wolfson SK Jr. Carotid artery intima and media thickness as a risk factor for myocardial infarction and smok in older adults. N Engl J Med. 1999 Jan &; 340(1): 14-22.

(5.) M Adaikkappan, R Sampath, AJW Felix, S Sethupathy. Evaluation of atherosclerosis by B mode Ultrasonographic study in Hypertensive patients compared with Normotensive Patients. IJRI 2002 12: 3: 365-368.

(6.) Patricia H. Davis, Jeffrey D. Dawson, Ward A. Riley, Ronald M. Lauer. Carotid Intimal-Medial Thickness Is Related to Cardiovascular Risk Factors Measured From Childhood through Middle Age, The Muscatine Study. Circulation. 2001; 104: 2815-2819.

(7.) Pignoli P, Tremoli E, Poli A, Oreste P, Paoletti R. Intimal plus medial thickness of the arterial wall: A direct measurement with ultrasound imaging. Circulation 1986; 74: 1399-406.

(8.) Simon A, Megnien JL, Levenson J. Coronary risk estimation and treatment of hypercholesterolemia. Circulation. 1997; 96 (7): 2449-52.

(9.) Aminbakhsh A, Mancini GB. Carotid intima-media thickness measurements: what defines an abnormality? A systematic review. Clin Invest Med.1999; (4): 149-57.

(10.) Greenland P, Abrams J, Aurigemma FP, Bondmg, Clark LT, Criqui MH, Crouse JR 3rd, Friedman L, Fuster V, Herrington DM, Kuller LH, Ridker PM, Roberts WC, Stanford W, Stone N, Swan HJ. Prevention Conference V: Beyong secondary prevention identifying the high-risk patient for primary prevention: noninvasive tests of atherosclerotic burden; Writing Group III. Circulation 2000; 101(1): E16-22.

(11.) Matsumoto K, Sera Y, Nakamura H, et al. Increased Common Carotid Artery Intima Media Thickness Is a Risk Factor for Ischemic Stroke in Patients with Type 2 Diabetes. Metabolism. 2002; 51: 244-247.

(12.) REN Hong-kun et al (2011), Study of Hypertension Effecting the Carotid Arteriosclerosis, REN Hong-kun, SUN Xio-zhen, WANG Ling (Department of Cardiology, Inner Mongolia Hospital, Hohhot 010017 China) Journal of Inner Mongolia Medical College, March-2011.

(13.) Jadhav UM, Kadam NN. Carotid intima-media thickness as an independent predictor of coronary artery disease. Indian Heart J 2001; 53(4): 458-62.

(14.) Fulesdi B, Bereczki D, Mihalka L et al. Carotid atherosclerotic lesions in stroke patients with diabetes mellitus. Orv Hetil 1999; 140 (13): 697-700.

(15.) A Kablak-Ziembicka et al (2004), Association f increased carotid intima-media thickness with the extent of coronary artery disease, A Kablak-Ziembicka, W Tracz, T Przewlocki, P Pieniazek, A Sokolowski, M Konieczynska, Heart 2004; 90: 1286-90.

(16.) Li S, Chen W, Srinivasan SR, Tang R, Bondmg, Berenson GS. Race (black-white) and gender divergences in the relationship of childhood cardiovascular risk factors to carotid artery intima-media thickness in adulthood: the Bogalus a Heart Study. Atherosclerosis. 2007; 194: 421-425.

(17.) Freedman BI, Hsu FC, Langefeld CD, Rich SS, Herrington DM, Carr JJ, Xu J, Bowden DW, Wagenknecht LE. The impact of ethnicity and sex on subclinical cardiovascular disease: the Diabetes Heart Study. Diabetologia. 2005; 48: 2511-2518.

(18.) Bennett PC, Gill PS, Silverman S, Blann AD, Lip GY. Ethnic differences in common carotid intimamedia thickness, and the relationship to cardiovascular risk factors and peripheral arterial disease: the Ethnic-Echocardiographic Heart of England Screening Study.

(19.) Marc B. Lande, Nancy L. Carson, Jason Roy and Cecilia C. Meagher Effects of Childhood Primary Hypertension on Carotid Intima Media Thickness. A Matched Controlled Study Effects. Hypertension. 2006; 48: 40-44; originally published online May 30, 2006.

(20.) Khalil A, Huffman MD, Prabhakaran D, Osmond C, Fall CH, Tandon N, Lakshmy R, Prabhakaran P, Biswas SK, Ramji S, Sachdev HS, Bhargava SK; On behalf of the New Delhi Birth Cohort. Predictors of carotid intima-media thickness and carotid plaque in young Indian adults: The New Delhi Birth Cohort. Int J Cardiol. 2012 Apr 24.

(21.) D Reed, K M Dwyer and J H Dwyer. Abdominal obesity and carotid artery wall thickness. The Los Angeles Atherosclerosis Study International Journal of Obesity.

Rupak Bhuyan [1], Gaurav Chayan Das [2], Arabinda Mandal [3], David Pegu [4], Indrani Deori [5], Sumit Ujawane [6], Stephenson Pohlong [7]

AUTHORS:

[1.] Rupak Bhuyan

[2.] Gaurav Chayan Das

[3.] Arabinda Mandal

[4.] David Pegu

[5.] Indrani Deori

[6.] Sumit Ujawane

[7.] Stephenson Pohlong

PARTICULARS OF CONTRIBUTORS:

[1.] Assistant Professor, Department of Radiology, Silchar Medical College and Hospital, Silchar, Assam.

[2.] Post Graduate Trainee, Department of Radiology, Silchar Medical College and Hospital, Silchar, Assam.

[3.] Post Graduate Trainee, Department of Radiology, Silchar Medical College and Hospital, Silchar, Assam.

[4.] Post Graduate Trainee, Department of Radiology, Silchar Medical College and Hospital, Silchar, Assam.

[5.] Post Graduate Trainee, Department of Radiology, Silchar Medical College and Hospital, Silchar, Assam.

[6.] Post Graduate Trainee, Department of Radiology, Silchar Medical College and Hospital, Silchar, Assam.

[7.] Post Graduate Trainee, Department of Radiology, Silchar Medical College and Hospital, Silchar, Assam.

FINANCIAL OR OTHER COMPETING INTERESTS: None

NAME ADDRESS EMAIL ID OF THE CORRESPONDING AUTHOR:

Dr. Rupak Bhuyan, Assistant Professor, Department of Radiology, Silchar Medical College and Hospital, Silchar, Assam-788014.

E-mail: bhuyan.rupak@gmail.com

Date of Submission: 10/09/2015.

Date of Peer Review: 11/09/2015.

Date of Acceptance: 14/09/2015.

Date of Publishing: 15/09/2015.

Table 1: Demographic variables of Hypertensive and Normotensive
subjects (age, sex, BMI matched as per the study protocol)

Characteristics       HTN Subjects (n=52)   Control Subjects (n=52)

Age                    42.8 [+ or -] 7.5      42.03 [+ or -] 7.3
Male (%)                     71.2                    71.2
BMI in kg/[m.sup.2]    26.3 [+ or -] 3.1       25.5 [+ or -] 2.6
Smoker (%)                   30.8                    23.1


Data expressed as Mean [+ or -] SD.

Table 2: Shows a comparison of office BP and cIMT of the
2 study groups

Characteristics      HTN subjects       Control Subjects

Systolic BP       153.1 [+ or -] 6.4   113.3 [+ or -] 4.01
Diastolic BP       87.9 [+ or -] 5.5    75.9 [+ or -] 2.6
CIMT (in mm)       0.66 [+ or -] 0.18   0.52 [+ or -] 0.01

Fig. 2: Shows the age and sex distribution of the
hypertensive subjects and figure 2 shows the blood
pressure distribution.

Fig. 2

Blood Pressure Distribution

Combined   31%
DBP        2%
SBP        67%

Note: Table made from pie chart.
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Title Annotation:ORIGINAL ARTICLE
Author:Bhuyan, Rupak; Das, Gaurav Chayan; Mandal, Arabinda; Pegu, David; Deori, Indrani; Ujawane, Sumit; Po
Publication:Journal of Evolution of Medical and Dental Sciences
Date:Sep 17, 2015
Words:2575
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