Published: 18 Jun 2025

ICD9: 405.91      ICD10: I15.0      ICD11: BD40.2

Renal artery stenosis (RAS) is a narrowing of one or both of the arteries that carry blood to your kidneys.
This narrowing restricts blood flow to the kidneys. When this happens, it can lead to:

Hypertension (high blood pressure): The kidneys respond to the reduced blood flow by releasing hormones that raise blood pressure. This type of high blood pressure caused by RAS is called renovascular hypertension.
Kidney damage: Over time, reduced blood flow can damage the kidney tissue, potentially leading to kidney failure.

Here's a more detailed breakdown:

Key Components:

Renal Arteries: These are the blood vessels that supply blood to the kidneys. Each kidney has its own renal artery.
Stenosis: This refers to the narrowing of a blood vessel. In RAS, it's the renal arteries that are narrowed.
Renovascular Hypertension: This is high blood pressure caused by a problem with the blood vessels supplying the kidneys (in this case, stenosis).

Causes:

Atherosclerosis: This is the most common cause. It's the buildup of plaque (cholesterol, fat, and other substances) inside the artery walls, causing them to narrow and harden. This is similar to what happens in coronary artery disease (heart disease).
Fibromuscular Dysplasia (FMD): This is a less common cause, particularly in younger women. FMD is a condition that causes abnormal cell growth in the artery walls, leading to narrowing, beading, and aneurysm formation.

How it Leads to Hypertension:

1. Reduced Blood Flow: The stenosis restricts the amount of blood reaching the kidneys.
2. Kidney Response: The kidneys perceive this reduced blood flow as a sign of low blood pressure or low blood volume.
3. Hormone Release: The kidneys release renin, an enzyme that activates the renin-angiotensin-aldosterone system (RAAS).
4. Increased Blood Pressure: The RAAS system causes the blood vessels to constrict and the body to retain sodium and water. This leads to increased blood volume and increased blood pressure.

Symptoms:

Difficult-to-control high blood pressure: Hypertension that doesn't respond well to standard medications.
Sudden onset of high blood pressure: Especially in people under 30 or over 50.
Worsening kidney function: Detected through blood tests.
Fluid retention (edema): Swelling in the legs, ankles, or feet.
Flash pulmonary edema: Sudden episodes of fluid buildup in the lungs, causing shortness of breath.
Abdominal bruit: A whooshing sound heard with a stethoscope over the abdomen, caused by turbulent blood flow through the narrowed artery (not always present).

Diagnosis:

Physical Exam and Medical History: Doctors will assess your risk factors and look for signs and symptoms.
Renal Artery Doppler Ultrasound: Uses sound waves to measure blood flow in the renal arteries.
CT Angiography (CTA): A CT scan with contrast dye to visualize the renal arteries.
MR Angiography (MRA): An MRI with contrast dye to visualize the renal arteries.
Renal Angiography (Arteriography): An invasive procedure where a catheter is inserted into an artery (usually in the groin) and guided to the renal arteries. Contrast dye is injected, and X-rays are taken to visualize the arteries. This is considered the gold standard for diagnosis but is more invasive.
Blood and Urine Tests: To assess kidney function.

Treatment:

The goals of treatment are to control blood pressure, preserve kidney function, and prevent complications.

Medications:
Antihypertensives: ACE inhibitors, ARBs, beta-blockers, calcium channel blockers, and diuretics are commonly used to lower blood pressure. However, ACE inhibitors and ARBs should be used with caution, particularly if stenosis affects both kidneys or a single functioning kidney, as they can worsen kidney function.
Antiplatelet Medications: Such as aspirin, to help prevent blood clots from forming in the narrowed artery.
Statins: To lower cholesterol levels, especially if atherosclerosis is the cause.
Renal Angioplasty and Stenting: A minimally invasive procedure where a balloon catheter is used to widen the narrowed artery, and a stent (a small mesh tube) is placed to keep the artery open.
Surgical Bypass: A more invasive option where a new blood vessel is surgically attached to bypass the narrowed segment of the renal artery. This is less commonly done.

Important Considerations:

Early diagnosis and treatment are crucial to prevent long-term complications.
The best treatment approach depends on the severity of the stenosis, the underlying cause, and the patient's overall health.
Regular monitoring of blood pressure and kidney function is essential after diagnosis and treatment.

In summary, renal artery stenosis is a condition where the arteries supplying the kidneys become narrowed, leading to reduced blood flow, high blood pressure (renovascular hypertension), and potential kidney damage. It requires careful diagnosis and management to protect kidney function and control blood pressure.

Disclaimer: This information is for general knowledge purposes only and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.*