CASE HISTORY:
An elderly gentleman on maintenance hemodialysis since 3-4 years, was admitted last week with complaints of breathing difficulty. He was admitted in ICU and treated with NIV support and dialysis, after which he settled. His cardiac function was evaluated and found to have LV dysfunction. The shortness of breath was attributed with the failing LV. However, on further analysis, it was found that he multiple episodes of pulmonary edema in the recent past, warranting admission and management. Cardiologist opinion was taken and CAG with drive by angiogram was done and found to have SVD with 90 % bilateral renal artery stenosis.
Introduction:
Renal artery stenosis (RAS) is a condition characterized by the narrowing of one or both renal arteries, leading to reduced renal perfusion. It is a significant and potentially reversible cause of secondary hypertension and chronic kidney disease (CKD). The clinical approach to RAS must balance diagnostic precision with evidence-based management strategies to preserve renal function and control blood pressure.
Etiology and Pathophysiology
The two most common etiologies of RAS are:
- Atherosclerotic Renal Artery Stenosis (ARAS)– accounts for over 90% of cases, typically in older patients with diffuse vascular disease [1,2].
- Fibromuscular Dysplasia (FMD)– more common in younger females and involves non-atherosclerotic, non-inflammatory arterial wall changes [3].
ARAS results in progressive luminal narrowing, reducing renal blood flow and activating the renin-angiotensin-aldosterone system (RAAS), leading to hypertension and ischemic nephropathy [4]. Chronic ischemia contributes to tubulointerstitial fibrosis and glomerulosclerosis, potentially culminating in end-stage renal disease (ESRD) [5].
Clinical Presentation
RAS may present in several ways:
- Refractory or accelerated hypertension
- Flash pulmonary edema (Pickering syndrome)
- Unexplained decline in renal function, especially after initiation of RAAS blockers
- Asymmetry in kidney size on imaging
- Abdominal bruit on auscultation
Diagnosis
The diagnostic workup begins with a high index of suspicion based on clinical clues. Confirmatory imaging includes:
- Doppler Ultrasound– non-invasive, operator-dependent, and sensitive in skilled hands [6].
- CT Angiography (CTA)– excellent anatomical detail but requires contrast [7].
- MR Angiography (MRA)– useful in patients with contrast allergies; however, gadolinium risks must be considered in CKD [8].
- Catheter-based Renal Angiography– the gold standard, primarily used when intervention is being considered [9].
Functional studies such as captopril-enhanced renography have fallen out of favor due to limited sensitivity and specificity [10].
Management
Medical therapy remains the cornerstone of RAS management, especially in ARAS:
- RAAS inhibitors (ACE inhibitors or ARBs)
- Calcium channel blockers
- Statins and antiplatelet therapy
- Lifestyle modifications and cardiovascular risk reduction
RAAS blockade is effective but should be used with caution in bilateral RAS or solitary kidney cases due to the risk of acute kidney injury (AKI) [11].
Revascularization is considered in select cases, such as:
- Recurrent flash pulmonary edema
- Rapidly declining renal function
- Resistant hypertension despite optimal medical therapy
However, randomized controlled trials like ASTRAL and CORAL have shown limited benefit of stenting over optimal medical therapy in unselected patients [12,13].
In contrast, patients with FMD often benefit more from revascularization, which can result in cure or significant improvement in blood pressure [14].
Prognosis and Follow-up
Outcomes depend on the underlying etiology, baseline renal function, and response to therapy. Regular follow-up with monitoring of renal function, blood pressure, and imaging when indicated is essential. Early detection and individualized treatment can significantly alter disease trajectory.
Conclusion
Renal artery stenosis is a multifaceted condition requiring a nuanced approach. While advances in imaging and pharmacotherapy have improved management, careful patient selection for intervention remains critical. Ongoing research is needed to better define which subgroups derive the most benefit from revascularization.
Dr. R. Balasubramaniyam
Chief Nephrologist
Kauvery Hospital Chennai
Dr. Rashmi Shivram
Resident – Nephrology
Kauvery Hospital Chennai
