Hypertension is a major global health burden and a leading contributor to cardiovascular morbidity and mortality. While the majority of cases are classified as essential hypertension, approximately 5–10% are secondary to identifiable and potentially reversible causes [1]. Among these, renal artery stenosis (RAS) is one of the most clinically significant etiologies, particularly in patients with resistant or poorly controlled hypertension [2].

RAS, defined as a partial or complete narrowing of one or both renal arteries, may result in renovascular hypertension and ischemic nephropathy. In elderly individuals, atherosclerosis is the predominant cause of RAS, whereas fibromuscular dysplasia is more commonly seen in younger patients [3]. Early diagnosis is vital, as timely therapeutic intervention can improve blood pressure control, restore renal perfusion, and prevent irreversible renal parenchymal damage [4].

Doppler ultrasonography (USG) is widely regarded as a first-line, non-invasive imaging modality for screening RAS due to its accessibility, safety, and cost-effectiveness [5]. It enables real-time assessment of renal arterial flow characteristics and hemodynamic parameters. Key Doppler indices include peak systolic velocity (PSV), renal-aortic ratio (RAR), and the presence of parvus-tardus waveforms in intrarenal branches, all of which are highly predictive of significant stenosis [6].

Although digital subtraction angiography (DSA) remains the gold standard, Doppler USG provides excellent sensitivity and specificity in experienced hands and is especially valuable for serial monitoring and screening in high-risk populations [7].

The present study was undertaken to evaluate the prevalence and severity of RAS among hypertensive patients using Doppler USG and to analyze its association with clinical risk factors such as duration of hypertension, diabetes mellitus, and smoking. Identifying high-risk individuals can facilitate early diagnosis and targeted management, thereby improving patient outcomes.

This observational cross-sectional study was conducted at the Department of Radiology, Government Medical College, Kamareddy, over a period of nine months from May 2024 to January 2025.

Study Population:

A total of 100 adult patients diagnosed with systemic hypertension and referred for renal Doppler ultrasonography were enrolled. Patients were selected consecutively based on inclusion and exclusion criteria.

Inclusion Criteria:

Patients aged ≥18 years with a clinical diagnosis of hypertension (as per JNC 8 criteria).

Patients who provided informed consent for participation.

Patients undergoing renal Doppler USG as part of evaluation for secondary hypertension.

Exclusion Criteria:

Patients with known renal artery intervention (angioplasty or stenting).

Patients with congenital renal anomalies or advanced chronic kidney disease (eGFR <30 ml/min/1.73 m²).

Poor acoustic window hindering adequate Doppler imaging.

Data Collection:

Detailed clinical history including age, gender, duration of hypertension, medication use, and presence of comorbidities such as diabetes and smoking history was recorded. Blood pressure was measured and biochemical parameters were noted where relevant.

Ultrasound Examination:

Renal Doppler ultrasonography was performed using a high-resolution ultrasound machine with a curvilinear probe (3.5–5 MHz). The following Doppler parameters were assessed:

Peak systolic velocity (PSV) of the main renal artery.

Renal-aortic ratio (RAR) (PSV renal artery / PSV aorta).

Parvus-tardus waveform in segmental/interlobar arteries.

Resistive index (RI) where applicable.

A PSV >180 cm/s, RAR >3.5, or presence of parvus-tardus waveform were considered indicative of significant RAS. Bilateral renal arteries were scanned in all patients.

Statistical Analysis:

Data were entered into Microsoft Excel and analyzed using SPSS version 26.0. Descriptive statistics were used to summarize demographic and clinical characteristics. The prevalence of RAS was expressed as a percentage. Chi-square test was used to determine the association between RAS and clinical risk factors, with a p-value <0.05 considered statistically significant.

Ethical Consideration:

The study was approved by the Institutional Ethics Committee of Government Medical College, Kamareddy. Informed written consent was obtained from all participants prior to enrollment.

A total of 100 hypertensive patients were evaluated using Doppler ultrasonography to assess the presence and characteristics of renal artery stenosis (RAS).

The mean age of participants was 56.4 ± 10.8 years, with a male predominance (58%) (Table 1).

Table 1: Demographic Characteristics of Study Participants (N = 100)

The duration of hypertension varied among participants, with 40% having hypertension for less than 5 years, 38% for 5–10 years, and 22% for more than 10 years (Table 2).

Table 2: Duration of Hypertension

Doppler ultrasonography revealed that 38 patients (38%) had evidence of renal artery stenosis, while 62 patients (62%) had normal renal Doppler findings (Table 3).

Table 3: Renal Doppler Ultrasonography Findings

Among those with RAS, unilateral involvement was observed in 26 patients (68.4%)—14 on the right and 12 on the left. Bilateral RAS was detected in 12 patients (31.6%). Regarding the severity of stenosis, 10 patients (26.3%) had mild RAS (PSV 180–200 cm/s), 15 patients (39.5%) had moderate RAS (PSV 200–300 cm/s), and 13 patients (34.2%) had severe stenosis, defined as peak systolic velocity >300 cm/s or luminal narrowing >60% (Table 4).

Table 4: Laterality and Severity of Renal Artery Stenosis (RAS) (n = 38)

Clinical risk factors significantly associated with RAS included uncontrolled hypertension (SBP >160 mmHg), which was present in 73.7% of RAS cases (p < 0.01), diabetes mellitus (57.9%, p = 0.03), and smoking history (52.6%, p = 0.04) (Table 5).

Table 5: Correlation of RAS with Clinical Risk Factors

These associations underscore the importance of considering comorbid conditions when evaluating hypertensive patients for renovascular causes.

This study evaluated the prevalence and clinical associations of renal artery stenosis (RAS) in hypertensive patients using Doppler ultrasonography at a tertiary care center in Kamareddy. The findings revealed that 38% of hypertensive patients had Doppler evidence of RAS, emphasizing the significant role of renovascular pathology in secondary hypertension. This prevalence aligns with earlier studies where RAS was identified in approximately 20–40% of patients with resistant hypertension, indicating the necessity for routine vascular imaging in such cases [8,9].

In our cohort, unilateral RAS was more common (68.4%) than bilateral disease (31.6%), which mirrors the typical pattern of atherosclerotic RAS, often presenting initially on one side and progressing over time [10]. The distribution of RAS severity—26.3% mild, 39.5% moderate, and 34.2% severe—demonstrates a substantial burden of hemodynamically significant stenosis. Parameters such as peak systolic velocity (PSV >300 cm/s) and renal-aortic ratio (RAR >3.5) were consistent with established Doppler thresholds for significant RAS and are well-validated in the literature [11,12].

A statistically significant association was observed between RAS and uncontrolled hypertension (p < 0.01), diabetes mellitus (p = 0.03), and smoking history (p = 0.04). These findings align with previous studies that have demonstrated strong correlations between RAS and metabolic risk factors such as diabetes and tobacco use, likely due to their role in accelerating vascular atherosclerosis [13].

Doppler ultrasonography proved to be a reliable, non-invasive imaging modality for initial screening and follow-up of RAS. It offers real-time assessment of both extrarenal and intrarenal vascular changes, and its diagnostic yield improves significantly when both approaches are combined [11]. Despite the continued role of digital subtraction angiography (DSA) as the gold standard, advancements in Doppler criteria and the incorporation of contrast-enhanced ultrasound (CEUS) have enhanced sensitivity and reduced the rate of technical failures [14].

This study is limited by its single-center design and lack of angiographic confirmation. However, the relatively large sample size and comprehensive assessment of risk factors enhance the robustness of the findings.

This study highlights the significant prevalence of renal artery stenosis (RAS) among hypertensive patients, with 38% demonstrating abnormal Doppler findings. Unilateral RAS was more common, and a substantial proportion of cases were moderate to severe in degree. The presence of uncontrolled hypertension, diabetes mellitus, and smoking history were significantly associated with RAS, underscoring the importance of comprehensive cardiovascular risk assessment. Doppler ultrasonography emerged as a reliable, non-invasive, and cost-effective modality for early detection of RAS in at-risk individuals. Routine screening using Doppler USG in selected hypertensive populations may facilitate timely diagnosis, targeted intervention, and improved blood pressure control, thereby reducing renal and cardiovascular complications.

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