Renovascular hypertension (RVH) is a type of high blood pressure caused by narrowing (stenosis) of the arteries that supply blood to the kidneys. This narrowing reduces blood flow to the kidneys, leading them to release hormones that increase blood pressure. Common causes include atherosclerosis (buildup of plaque in the arteries) and fibromuscular dysplasia (abnormal growth of artery walls). Renovascular hypertension can lead to kidney damage and cardiovascular problems if left untreated, but it can often be managed with medication, lifestyle changes, or surgical interventions to improve blood flow.

What is renovascular ypertension?

Renovascular Hypertension is a form of high blood pressure caused by the narrowing or blockage of one or both arteries that supply blood to the kidneys. When the blood flow to the kidneys is reduced, they respond by activating the renin-angiotensin-aldosterone system (RAAS), leading to an increase in blood pressure to compensate for the perceived lack of blood supply.

Symptoms might not always be apparent, but it can lead to severe high blood pressure that is resistant to standard medications. If untreated, it can result in kidney damage and increase the risk of heart disease.

Causes of renovascular hypertension

The primary causes of RVHinclude:

• Atherosclerosis: A common cause, especially in older adults, where fatty deposits (plaque) build up inside the walls of the renal arteries. This reduces blood flow to the kidneys, triggering a rise in blood pressure. Risk factors include smoking, high cholesterol, diabetes, hypertension, and age.
  • Fibromuscular dysplasia (FMD): A condition characterized by abnormal cell growth within the walls of the renal arteries, leading to narrowing or twisting. It usually affects younger women and can be hereditary or influenced by hormonal factors.
  • Renal artery thrombosis: A blood clot in the renal artery can reduce blood flow to the kidneys, causing a sudden increase in blood pressure. It may result from injury, a hypercoagulable state, or atherosclerosis.
  • Renal artery embolism: A condition where a clot or debris from another part of the body blocks a renal artery, leading to reduced blood supply and hypertension.
  • Vasculitis: Inflammation of the blood vessels, including renal arteries, can narrow the vessels and affect blood flow, causing hypertension.
  • Congenital abnormalities: Some individuals may have structural abnormalities in the renal arteries present from birth, which can lead to reduced blood flow and elevated blood pressure.

Diagnosis of renovascular hypertension

The diagnosis of RVH involves a combination of medical history, physical examination, blood and urine tests, and specialized imaging studies to identify reduced blood flow to the kidneys. Key diagnostic methods include:

• Blood tests: Measurement of kidney function through serum creatinine and blood urea nitrogen (BUN) levels. Testing for elevated levels of renin and aldosterone, which can indicate disrupted kidney blood flow.
  • Urine tests: To check for protein or blood in the urine, which might indicate kidney damage.
  • Doppler ultrasound: A non-invasive test that uses sound waves to evaluate blood flow in the renal arteries and detect narrowing or blockage.
  • CT angiography (CTA): A detailed imaging technique that uses X-rays and contrast dye to visualize the renal arteries and identify any narrowing.
  • Magnetic resonance angiography (MRA): A non-invasive imaging method that uses magnetic fields and contrast dye to view blood flow in the renal arteries.
  • Renal arteriography: An invasive test considered the gold standard for diagnosing renal artery stenosis. It involves injecting contrast dye directly into the renal arteries through a catheter to obtain high-resolution images.
  • Renal scintigraphy (Nuclear Medicine Scan): A test that uses a small amount of radioactive material to assess kidney function and blood flow before and after administering an ACE inhibitor (a medication that lowers blood pressure). It helps identify reduced perfusion due to stenosis.
  • Captopril renography: A special form of renal scintigraphy performed after taking Captopril (an ACE inhibitor) to detect abnormal blood flow patterns suggestive of renal artery stenosis.
  • Measurement of blood pressure: Blood pressure readings in both arms and legs may be taken to assess any discrepancies, and ambulatory blood pressure monitoring over 24 hours may help document consistently high readings Symptoms of “Renovascular Hypertension”

What are the symptoms of RVH?

In some cases, RVH may be asymptomatic and discovered incidentally during evaluations for other health issues. The symptoms can vary depending on the severity of the condition, but common signs and symptoms include:

• Severe or resistant high blood pressure: Blood pressure that is difficult to control with standard medications. Sudden onset of high blood pressure, especially in individuals under 30 or over 55.
  • Decreased kidney function
  • Unexplained fluid retention (edema)
  • Sudden onset of hypertension:
  • Abdominal bruit: A whooshing sound heard over the abdomen during a physical exam, caused by turbulent blood flow in a narrowed renal artery.
  • Recurrent pulmonary edema
  • Fatigue and weakness
  • Nausea or vomiting

Treatment of renovascular yypertension

The treatment of RVH focuses on lowering blood pressure, improving blood flow to the kidneys, and preventing kidney damage. Treatment options include:

Medications

• Antihypertensive drugs
• Statins: To manage cholesterol levels if atherosclerosis is the cause.
• Antiplatelet agents (e.g., Aspirin): To reduce the risk of blood clots in cases of atherosclerosis.

Lifestyle Changes

• Dietary modifications
• Regular exercise
• Weight management
• Smoking cessation
• Stress management:
• Limiting alcohol ıntake:

Angioplasty and stenting

A minimally ınvasive procedure to widen narrowed renal arteries using a balloon (angioplasty) and placing a stent to keep the artery open.

Surgical intervention

• Renal artery bypass surgery:
• Endarterectomy:

Summary

Renovascular hypertension is high blood pressure caused by narrowed arteries supplying blood to the kidneys. This narrowing reduces blood flow, triggering the kidneys to release hormones that raise blood pressure. The primary causes are atherosclerosis (plaque buildup) and fibromuscular dysplasia (abnormal artery growth). Symptoms may include severe high blood pressure, decreased kidney function, and fluid retention. Diagnosis involves blood and urine tests, imaging like Doppler ultrasound or CT angiography, and sometimes invasive angiography. Treatment options include antihypertensive medications, lifestyle changes, angioplasty with stenting, or surgery to restore proper blood flow.

Prof. Dr. Emin ÖZBEK

Urologist

Istanbul- TURKIYE