Hypertension is a major global public health problem, affecting more than 1.4 billion adults and contributing substantially to cardiovascular morbidity and mortality [1,2]. In India, hypertension affects a considerable proportion of the adult population, while many individuals remain undiagnosed or inadequately controlled [3,4]. Beyond sustained elevation of arterial pressure, hypertension promotes vascular injury through mechanical stress, endothelial dysfunction, oxidative stress, arterial stiffening, and neurohormonal activation [5,6]. These processes contribute to the development of atherosclerosis and increase the risk of myocardial infarction, stroke, heart failure, and cardiovascular death [7].

Cardiovascular risk assessment in patients with hypertension is commonly based on blood pressure level and established clinical risk factors, including age, sex, smoking, diabetes mellitus, and dyslipidaemia [8]. However, conventional risk-factor assessment may not fully characterize subclinical vascular injury. Non-invasive vascular imaging can therefore provide complementary information by detecting structural arterial changes before overt cardiovascular disease becomes clinically apparent [9-11]. Carotid intima-media thickness (CIMT) and carotid plaque detected by B-mode and Doppler ultrasonography are among the most widely studied markers of subclinical atherosclerosis [12-14].

Carotid Doppler ultrasonography is non-invasive, radiation-free, widely available, and relatively inexpensive. It enables direct evaluation of the carotid arterial wall and vascular haemodynamics [15]. CIMT is measured as the distance between the lumen-intima and media-adventitia interfaces of the far wall of the common carotid artery and has been used as a surrogate marker of atherosclerotic vascular disease [16,17]. Carotid plaque represents a more focal and advanced manifestation of arterial disease [18]. Doppler-derived parameters, including peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), and pulsatility index, also provide information regarding blood-flow patterns and peripheral vascular resistance [19,20].

Data describing carotid morphological and haemodynamic abnormalities among hypertensive patients in South India remain limited. The present study therefore evaluated carotid Doppler findings in hypertensive patients attending a tertiary care hospital in Tamil Nadu, with emphasis on CIMT, plaque burden, and their relationships with clinical and biochemical cardiovascular risk variables.

OBJECTIVES

The primary objective was to evaluate the role of carotid Doppler ultrasonography in cardiovascular risk assessment among hypertensive patients by measuring CIMT, identifying carotid plaques, and assessing Doppler-derived haemodynamic parameters, including PSV, EDV, and RI.

The secondary objectives were to estimate the prevalence of subclinical carotid atherosclerosis; examine associations between carotid Doppler findings and demographic, clinical, and biochemical variables; and determine whether carotid Doppler measurements provide additional information relevant to cardiovascular risk stratification.

Study Design and Setting A hospital-based cross-sectional observational study was conducted in the Department of Radiodiagnosis in collaboration with the Department of General Medicine at a tertiary care hospital in Tamil Nadu, India. The study was carried out over eight months, from July 2018 to February 2019. Study Population and Sample Size A total of 48 patients with established essential hypertension were enrolled. The sample size was based on the expected prevalence of abnormal CIMT reported in previous Indian studies, using a 95% confidence level and 10% absolute precision. The calculated minimum sample size was 46; 48 participants were recruited to account for potential attrition. Ethical Considerations The study protocol was approved by the Institutional Ethics Committee. Written informed consent was obtained from all participants before enrolment. Inclusion Criteria Patients aged 30-70 years, of either sex, with documented essential hypertension were eligible. Hypertension was defined according to the JNC-7 criteria as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg on at least two occasions, or current use of antihypertensive medication. Participants were also required to provide informed consent and complete the specified investigations, including carotid Doppler ultrasonography. Exclusion Criteria Patients were excluded if they had secondary hypertension; known coronary artery disease; previous myocardial infarction, stroke, or transient ischaemic attack; known carotid artery stenosis or previous carotid endarterectomy; chronic kidney disease with serum creatinine >2 mg/dL; malignancy; chronic liver disease; pregnancy; or acute illness. Patients with inadequate acoustic windows or incomplete study evaluation were also excluded. Clinical and Laboratory Assessment Demographic characteristics, duration of hypertension, medication history, smoking and alcohol use, family history of cardiovascular disease, and anthropometric measurements were recorded using a structured case record form. Blood pressure was measured in the sitting position after five minutes of rest with a calibrated mercury sphygmomanometer. Two measurements were obtained five minutes apart, and the mean value was recorded. Fasting venous blood samples were analysed for total cholesterol, triglycerides, LDL cholesterol, HDL cholesterol, fasting blood glucose, and serum creatinine. Carotid Doppler Ultrasonography Bilateral carotid Doppler ultrasonography was performed by an experienced radiologist using a Philips HD11 XE ultrasound system (Philips Healthcare, Best, Netherlands) with a 7.5-10 MHz linear-array transducer. The common carotid artery (CCA), carotid bifurcation, and internal and external carotid arteries were examined bilaterally. CIMT was measured on the far wall of the CCA approximately 1 cm proximal to the bifurcation as the distance between the lumen-intima and media-adventitia interfaces. Three measurements were obtained and averaged. A CIMT >0.9 mm was classified as abnormal. Carotid plaque was defined as a focal structure encroaching into the arterial lumen by ≥0.5 mm or >50% of the surrounding CIMT value, or as a focal thickness >1.5 mm. Spectral Doppler analysis was used to measure PSV and EDV in the CCA, and RI was calculated as (PSV - EDV)/PSV. Statistical Analysis Data were entered into Microsoft Excel and analysed using IBM SPSS Statistics version 22.0 (IBM Corp., Armonk, NY, USA). Continuous variables were summarized as mean ± standard deviation (SD) and compared using the independent-samples Student's t-test or Mann-Whitney U test, as appropriate. Categorical variables were expressed as frequencies and percentages and compared using the chi-square test or Fisher's exact test. Pearson's correlation coefficient was used to assess associations between CIMT and continuous variables. Multivariable linear regression analysis was performed to identify independent predictors of CIMT. A two-sided p-value <0.05 was considered statistically significant.

Baseline Characteristics

The study included 48 hypertensive patients, comprising 28 males (58.3%) and 20 females (41.7%). The mean age was 52.4 ± 10.2 years, and the mean duration of hypertension was 6.8 ± 4.2 years. Mean systolic and diastolic blood pressures were 152.4 ± 14.6 mmHg and 94.2 ± 8.8 mmHg, respectively. Baseline clinical and biochemical characteristics are summarized in Table 1.

Table 1: Baseline Characteristics of Study Participants (n=48)

Carotid Doppler Findings

The mean CIMT was 0.94 ± 0.18 mm. Abnormal CIMT (>0.9 mm) was detected in 33 patients (68.8%), while carotid plaques were present in 25 patients (52.1%). Among patients with plaque, the carotid bifurcation was the most frequent site (68.0%). Mean CCA PSV, EDV, and RI were 56.8 ± 12.4 cm/s, 15.2 ± 4.6 cm/s, and 0.72 ± 0.08, respectively. Patients with plaque had significantly greater CIMT (1.06 ± 0.16 mm vs 0.82 ± 0.12 mm; p<0.001) and RI (0.76 ± 0.08 vs 0.67 ± 0.06; p=0.001) than patients without plaque.

Table 2: Carotid Doppler Findings in Hypertensive Patients (n=48)

Correlation and Regression Analyses

CIMT showed significant positive correlations with age (r=0.52, p<0.001), duration of hypertension (r=0.48, p=0.002), systolic blood pressure (r=0.41, p=0.006), and LDL cholesterol (r=0.36, p=0.018). Correlations with diastolic blood pressure, BMI, total cholesterol, triglycerides, and fasting blood glucose did not reach statistical significance. In multivariable linear regression analysis, age (β=0.38, p=0.002), duration of hypertension (β=0.32, p=0.008), and systolic blood pressure (β=0.28, p=0.022) were reported as independent predictors of CIMT.

Table 3: Correlation of CIMT with Clinical and Biochemical Variables

This study found a substantial burden of subclinical carotid atherosclerosis among hypertensive patients. More than two-thirds of participants had abnormal CIMT, and approximately half had detectable carotid plaque. The mean CIMT of 0.94 mm is broadly comparable with findings from previous Indian studies reporting increased CIMT in patients with hypertension [9,11,18]. These observations reinforce the association between chronic blood-pressure elevation and structural carotid arterial changes. The observed plaque prevalence of 52.1% further indicates that a considerable proportion of the study population had focal carotid atherosclerotic disease. Plaques were most commonly located at the carotid bifurcation, a region known to be susceptible to atherosclerotic change because of disturbed blood flow, low wall shear stress, and local haemodynamic complexity [15]. Previous studies and meta-analyses have similarly demonstrated greater carotid structural abnormalities in sustained, white-coat, and masked hypertension than in normotensive groups [12,13]. CIMT increased significantly with age, longer duration of hypertension, higher systolic blood pressure, and higher LDL cholesterol. These associations are biologically plausible because ageing, cumulative haemodynamic load, and lipid-mediated vascular injury all contribute to arterial remodelling and atherogenesis [5,6,10]. Age, duration of hypertension, and systolic blood pressure remained significant in multivariable analysis, suggesting that cumulative exposure to elevated blood pressure may be particularly relevant to carotid wall thickening in this cohort. The higher RI observed among patients with plaque suggests an accompanying alteration in carotid haemodynamics. RI is influenced by downstream vascular resistance and arterial compliance and may therefore reflect functional vascular changes in addition to structural disease [19,20]. However, the cross-sectional design does not establish whether an elevated RI independently predicts subsequent cardiovascular events. These findings support the use of carotid ultrasonography as a complementary vascular assessment modality in selected hypertensive patients. Because carotid Doppler is non-invasive, radiation-free, and relatively accessible, it may help identify patients with subclinical vascular disease who warrant careful review of modifiable cardiovascular risk factors. Nevertheless, clinical management decisions should remain based on the overall cardiovascular risk profile and established guideline recommendations rather than carotid ultrasound findings alone. Limitations This study has several limitations. The sample size was small, which limits precision and statistical power. Its cross-sectional design prevents causal inference and does not permit assessment of whether carotid Doppler abnormalities predict future cardiovascular events. The study was conducted at a single tertiary care centre, which may limit generalizability to other populations and care settings. CIMT was measured by a single operator, so inter-observer variability could not be assessed. Information on medication adherence, duration of statin therapy, and lifestyle factors was not comprehensively captured. In addition, the absence of a normotensive control group prevented direct comparison of carotid Doppler parameters between hypertensive and normotensive individuals in this population.

In this cohort of hypertensive patients from a tertiary care hospital in Tamil Nadu, carotid Doppler ultrasonography demonstrated a high prevalence of abnormal CIMT and carotid plaque. CIMT was significantly associated with age, duration of hypertension, systolic blood pressure, and LDL cholesterol, while RI was higher in patients with carotid plaque. These findings indicate that carotid Doppler ultrasonography can provide complementary information on subclinical vascular involvement in hypertension. Larger prospective studies are required to determine the incremental prognostic value of CIMT, carotid plaque, and Doppler haemodynamic indices for cardiovascular event prediction in Indian hypertensive populations.

Acknowledgements

The authors acknowledge the support of the Departments of Radiodiagnosis, General Medicine, and Biochemistry at the participating tertiary care hospital, as well as the ultrasound technical staff. The authors also thank all patients who participated in the study and the Institutional Ethics Committee for its guidance.

1. World Health Organization. Hypertension. Geneva: WHO; 2023. 2. GBD 2019 Risk Factors Collaborators. Global burden of 87 risk factors in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet. 2020;396(10258):1223–1249. 3. Anchala R, Kannuri NK, Pant H, Khan H, Franco OH, Di Angelantonio E, et al. Hypertension in India: a systematic review and meta-analysis of prevalence, awareness, and control of hypertension. J Hypertens. 2014;32(6):1170–1177. 4. Gupta R, Guptha S, Sharma KK, Gupta A, Deedwania P. Regional variations in cardiovascular risk factors in India: India heart watch. World J Cardiol. 2012;4(4):112–120. 5. Schiffrin EL. The vascular phenotypes in hypertension: a new paradigm for understanding the pathogenesis of hypertension. Hypertension. 2012;59(2):179–185. 6. Dumor K, Shoemaker-Moyle M, Nistala R, Whaley-Connell A. Arterial stiffness in hypertension: an update. Curr Hypertens Rep. 2018;20(8):72. 7. Lewington S, Clarke R, Qizilbash N, Peto R, Collins R; Prospective Studies Collaboration. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies. Lancet. 2002;360(9349):1903–1913. 8. Williams B, Mancia G, Spiering W, Agabiti Rosei E, Azizi M, Burnier M, et al. 2018 ESC/ESH Guidelines for the management of arterial hypertension. Eur Heart J. 2018;39(33):3021–3104. 9. Kaur H, Ranjan RK, Xalxo AR, Rai N, Toppo SK, Kumari A, et al. Sonographic and Doppler evaluation of carotid artery in hypertensive and normotensive individuals. J Pharm Bioallied Sci. 2024;16(Suppl 4):S3673–S3675. 10. Cuspidi C, Sala C, Tadic M, Rescaldani M, Grassi G, Mancia G. Untreated masked hypertension and subclinical cardiac damage: a systematic review and meta-analysis. Am J Hypertens. 2015;28(6):806–813. 11. Khutan H, Aggarwal S, Kajal KS, Garg R, Kaur R, Kaur A. Study of carotid intimal medial thickness in essential hypertension with or without left ventricular hypertrophy. Ann Afr Med. 2017;16(4):192–195. 12. Cuspidi C, Sala C, Tadic M, Rescaldani M, Grassi G, Mancia G. Is white-coat hypertension a risk factor for carotid atherosclerosis? A review and meta-analysis. Blood Press Monit. 2015;20(2):57–63. 13. Cuspidi C, Sala C, Tadic M, Rescaldani M, Grassi G, Mancia G. Untreated masked hypertension and carotid atherosclerosis: a meta-analysis. Blood Press. 2015;24(2):65–71. 14. Cai A, Mo Y, Zhang Y, Li J, Zhu X, Lin J, et al. Relationship of pulse pressure index and carotid intima-media thickness in hypertensive adults. Clin Exp Hypertens. 2015;37(4):267–270. 15. Sun P, Liu L, Liu C, Zhang Y, Yang Y, Qin X, et al. Carotid intima-media thickness and the risk of first stroke in patients with hypertension. Stroke. 2020;51(2):572–579. 16. Kaul S, Alladi S, Mridula RK, Bandaru VCS, Boddu DB, Anjanikumar D, et al. Prevalence and risk factors of carotid intima-media thickness in asymptomatic individual subjects in a tertiary care center in India. Ann Indian Acad Neurol. 2015;18(4):430–434. 17. Shanmuga Jayanthan S, Sailagundla KK, Rupesh G, Devipriya, Nadanasadharam K, Yuvaraj N. Silent stroke: role of carotid Doppler in hypertensive patients as a screening tool for the detection of silent stroke with MRI correlation. J Cardiovasc Dis Res. 2024;15(12):848–856. 18. Sethi R, Kumar P, Rastogi A, Bhargava S, Kumar R, Chandra A, et al. A study to derive distribution of carotid intima media thickness and to determine its correlation with cardiovascular risk factors in asymptomatic nationwide Indian population (SCORE-India). Indian Heart J. 2016;68(6):821–827. 19. Gadhvi HJ, Makwana MB, Patel VJ. Assessment of carotid sonographic parameter pulsatility index associated with stroke risk among hypertension with diabetic stroke patients compared to hypertension with diabetic controls. Indian J Radiol Imaging. 2020;30(3):322–328. 20. Phan HAO. Morphological and hemodynamic features of the carotid artery on Doppler ultrasound in hypertensive patients. Eur Heart J Cardiovasc Imaging. 2025;26(Suppl 1):jeae333.400.