renal artery
Summary
The renal arteries are paired vessels arising from the abdominal aorta (typically at L1-L2) that supply oxygenated blood to the kidneys. The right renal artery is longer and passes posterior to the IVC, while the left is shorter. Renal artery stenosis, often due to atherosclerosis or fibromuscular dysplasia, is a key cause of secondary hypertension.
Detail
The renal arteries branch directly off the abdominal aorta just below the superior mesenteric artery, typically at the L1-L2 vertebral level. Each renal artery divides into segmental arteries, then interlobar, arcuate, and interlobular arteries, ultimately forming afferent arterioles that supply the glomeruli. Accessory renal arteries are a common anatomical variant, especially on the left, and are clinically relevant in renal transplant surgery and evaluation.
Clinically, renal artery stenosis is the most important pathology: in older patients it is usually caused by atherosclerotic plaque (typically at the ostium), while in younger patients—especially women—fibromuscular dysplasia causes a characteristic 'string of beads' appearance on angiography, often affecting the distal two-thirds of the artery. Renal artery stenosis leads to decreased perfusion pressure to the affected kidney, activating the renin-angiotensin-aldosterone system (RAAS). This causes elevated renin, angiotensin II-mediated vasoconstriction, and aldosterone-driven sodium/water retention, resulting in secondary hypertension. This is a classic cause of resistant hypertension and can present with an abdominal bruit on exam.
A key pharmacologic point: ACE inhibitors or ARBs can precipitate acute kidney injury in patients with bilateral renal artery stenosis (or stenosis in a solitary kidney) because efferent arteriolar dilation (normally mediated by decreased angiotensin II) drops glomerular filtration pressure critically when the afferent supply is already compromised. This is tested frequently on Step 1 and Step 2.
Diagnostic workup includes duplex ultrasound, CT angiography, MR angiography, or catheter angiography (gold standard). Treatment includes medical management of blood pressure, and in select cases, angioplasty with stenting, particularly for fibromuscular dysplasia which has better revascularization outcomes than atherosclerotic disease.
Sources
- First Aid for the USMLE Step 1
- Robbins Basic Pathology
- Guyton and Hall Textbook of Medical Physiology
- UpToDate: Renal artery stenosis
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.