Renal ArteryEdit
The renal arteries are the primary vessels that deliver arterial blood to the kidneys, the organs responsible for filtering the blood, maintaining fluid and electrolyte balance, and regulating blood pressure through hormonal signaling. Each kidney is supplied by a renal artery that ordinarily arises from the abdominal aorta around the level of the first or second lumbar vertebra and enters the kidney at the hilum. From there, the artery branches into segmental arteries that irrigate distinct regions of the renal parenchyma, continuing as interlobar, arcuate, and interlobular arteries that feed the glomeruli and the peritubular capillary network. The kidneys receive roughly a quarter of resting cardiac output, underscoring the central role of the renal arteries in systemic physiology. abdominal aorta Renal hilum Renal arteries cardiac output
The arterial supply within the kidney forms an end-arterial tree that optimizes filtration while allowing regional perfusion to be regulated independently. Blood reaches the glomeruli via afferent arterioles and exits through efferent arterioles, with the microvascular beds of the cortex and medulla arranged to support glomerular filtration, tubular reabsorption, and concentration of urine. The kidneys’ capacity to maintain stable glomerular filtration rate across a range of blood pressures is achieved through autoregulatory mechanisms, but the system is also tightly integrated with hormonal signaling, particularly the renin-angiotensin-aldosterone system, which modulates vascular tone and salt balance in response to changes in renal perfusion. glomerulus afferent arteriole efferent arteriole renal cortex renal medulla renin-angiotensin-aldosterone system
The renal arteries’ clinical importance becomes most evident in disease states that impair renal perfusion. Renal artery stenosis, whether due to atherosclerosis in older adults or fibromuscular dysplasia in younger patients, reduces perfusion pressure to the kidney and can contribute to secondary hypertension and progressive renal dysfunction. Other vascular conditions include renal artery aneurysm, dissection, and rare thrombotic events, all of which threaten kidney perfusion and overall cardiovascular health. Diagnostic imaging—ranging from Doppler ultrasonography toCT angiography and MR angiography—helps delineate the anatomy and assess hemodynamic significance, while definitive assessment may involve catheter-based angiography. Treatments span tight blood-pressure control and renal-protective strategies with medications such as ACE inhibitors or angiotensin receptor blockers, to revascularization in selected cases where restoration of perfusion yields meaningful clinical benefit. Doppler ultrasonography CT angiography MR angiography renal artery stenosis ACE inhibitors angiotensin receptor blockers renal perfusion
Anatomy
Origin and course
The renal arteries typically arise from the lateral aspects of the abdominal aorta near the level of the first lumbar vertebra, just below the superior mesenteric artery. Each artery traverses toward the kidney and enters at the hilum, where it often gives off segmental branches. From there, the arterial tree proceeds to feed the renal cortex and medulla through progressively smaller vessels. The right renal artery may have a longer course and a slightly different relation to adjacent retroperitoneal structures compared with the left, but both ultimately supply the same functional units of the kidney. abdominal aorta Renal hilum
Branches and microcirculation
Following the segmental arteries, blood flow advances to interlobar arteries, then arcuate arteries at the corticomedullary junction, and finally to interlobular arteries that feed the glomerular capillaries. The kidney’s microcirculation forms an architectural pattern that supports filtration and selective reabsorption, with the cortex receiving a rich blood supply and the medullary vasa recta accommodating concentrating mechanisms. The end-artery nature of the intrarenal circulation means that occlusion of a specific arterial branch can lead to localized infarction without extensive collateral support. segmental arteries interlobar arteries arcuate arteries interlobular arteries glomerulus renal cortex renal medulla
Functional relationship with the rest of the circulation
Venous drainage proceeds via the renal veins into the inferior vena cava, and the entire renal circulation operates in tight concert with systemic hemodynamics. The renal arteries’ performance influences and is influenced by systemic arterial pressure, circulating volumes, and neurohormonal signals that coordinate renal function with cardiovascular status. renal vein inferior vena cava systemic arterial pressure
Physiology
Autoregulation and filtration
The kidneys maintain a relatively constant glomerular filtration rate (GFR) across a spectrum of arterial pressures through autoregulatory mechanisms, including the myogenic response and tubuloglomerular feedback. This stability supports consistent waste excretion and fluid/electrolyte balance. The renal arteries contribute to this process by delivering blood at pressures compatible with stable filtration, while local autoregulation preserves organ function even as systemic pressures fluctuate. glomerular filtration rate autoregulation
Renin-angiotensin-aldosterone system and blood pressure
Renin release from juxtaglomerular cells responds to changes in perfusion pressure and sodium delivery to the distal tubule. Renin catalyzes a cascade producing angiotensin II, which constricts efferent arterioles and stimulates aldosterone secretion, thereby increasing blood pressure and promoting sodium reabsorption. This pathway links the renal arteries’ perfusion status to systemic blood pressure and volume homeostasis, illustrating why renal perfusion and the health of the renal arteries are central to cardiovascular regulation. renin angiotensin II aldosterone renin-angiotensin-aldosterone system
Clinical significance of flow and perfusion
Disruptions in renal arterial blood flow can have outsized effects on both kidney function and systemic hemodynamics. For instance, chronic reduction in renal perfusion can contribute to sustained hypertension, while abrupt changes in flow may precipitate acute kidney injury under certain conditions. Diagnostic and therapeutic decisions often hinge on the balance between restoring perfusion and minimizing invasive interventions. renal perfusion hypertension acute kidney injury
Pathology
Renal artery stenosis
Renal artery stenosis (RAS) is a major vascular cause of secondary hypertension and can accelerate renal dysfunction if perfusion remains compromised. Atherosclerotic disease is a common cause in older adults, while fibromuscular dysplasia is a notable cause in younger patients, especially women. Diagnosis relies on imaging that demonstrates reduced luminal area and signs of hemodynamic impact. Management includes meticulous blood-pressure control and consideration of renal-revascularization in selected cases, particularly when hypertension is resistant or renal function is deteriorating despite optimal medical therapy. atherosclerosis fibromuscular dysplasia renal artery stenosis
Other vascular conditions
Renal artery aneurysm and dissection are important but less common considerations, while rare thrombotic events can acutely threaten kidney viability. Each condition requires careful imaging assessment and risk stratification to determine the best management approach. renal artery aneurysm renal artery dissection thrombosis
Diagnosis and management
Diagnostic workups combine noninvasive imaging (Doppler ultrasonography, CT angiography, MR angiography) with invasive angiography when indicated. Medical therapy focuses on antihypertensive and renin-angiotensin-aldosterone system–modulating strategies to protect renal function and reduce cardiovascular risk. Revascularization through percutaneous angioplasty with or without stenting, or surgical bypass, is reserved for patients with clear indications such as resistant hypertension, rapidly progressive renal impairment, or recurrent heart failure symptoms related to volume overload. The evidence base for routine revascularization in all patients with RAS remains debated, with landmark trials shaping contemporary practice. Doppler ultrasonography CT angiography MR angiography angioplasty revascularization renal artery stenosis
Controversies and debates
There is ongoing debate about the role and timing of invasive intervention for renal artery stenosis. Randomized trials such as ASTRAL and CORAL found no broad, sustained advantage of renal-artery stenting over optimized medical therapy for a wide patient population, leading many guidelines to favor medical management as first-line treatment. Critics argue that these trials may have included patients unlikely to benefit from revascularization and that certain subgroups—such as those with resistant hypertension, rapidly declining renal function, or flash pulmonary edema due to renovascular disease—could still gain from targeted revascularization. From a practical, results-oriented perspective, those making decisions about care emphasize proven outcomes, cost-effectiveness, and patient-specific factors, preferring selective intervention when data indicate a meaningful likelihood of benefit and avoiding unnecessary procedures. ASTRAL trial CORAL trial revascularization renal artery stenosis