Renal Artery Stenosis (RAS) is the disease caused by narrowing of the arteries that carry blood to the kidneys. The narrowing is known as Renal Artery Stenosis (RAS). Renal Artery Stenosis (RAS) results in reduced blood flow to the kidneys causing a variety of symptoms. In this article, we will discuss about the various causes, symptoms, and treatments for Renal Artery Stenosis. The disease is observed in patient suffering with fibromuscular dysplasia, vasculitis, thromboembolism and aneurysms.1
How Do We Define Renal Artery Stenosis (RAS)?
- Renal Artery Stenosis (RAS)-
- Narrowing of renal artery is known as renal artery stenosis.
- Blood Supply To Kidney-
- Renal artery stenosis reduces blood supply to kidney tissue.
- Decreased blood flow to kidney tissue stimulates increased secretion of angiotensin hormone.
- Angiotensin causes narrowing of peripheral blood vessels (constriction).
- The disease is often observed in the elderly populations who have a condition called atherosclerosis.4
- Renal Artery Stenosis tends to get worse with time and results in hypertension.2
- Hypertension is caused by vasoconstriction of peripheral blood vessels.3
- Vasoconstriction is caused by persistent contraction of smooth muscles of blood vessels.
- The smooth muscles contract following stimulation by angiotensin hormone.2
- Congestive Heart Failure (CHF)-
- Persistent high blood pressure causes congestive heart failure
- CHF is observed in elderly patient.
- Renal Dysfunction-
- Prolonged reduced blood supply to kidney results in end stage kidney disease.2
Causes of Renal Artery Stenosis (RAS)
- In majority of cases, Renal Artery Stenosis is caused by Atherosclerosis or hardening of the arteries.
- Atherosclerosis is a disease caused by a build up of plaque on the walls of the blood vessels, which includes renal artery.
- Eighty percent of the renal artery stenosis is caused by renal artery atherosclerosis.
- Fibromuscular Dysplasia1
- Rare congenital disorder associated with renal artery stenosis.
- The muscular disorder causes abnormal growth of arterial smooth muscles, which results in thickening of smooth muscles.
- Thickening of smooth muscles narrows the lumen and causes stenosis.
Risk Factors For Renal Artery Stenosis (RAS)
Some Of The Risk Factors For Renal Artery Stenosis (RAS) Are:
- Age- Seen mostly in elderly population of age above 50 years
- Sex- More common among female patients.
- Family History Of Vascular Disease-
- Coronary artery disease
- Peripheral vascular disease
- Congestive heart failure
- Smoking- Patient with history of chronic smoking may suffer with weakness in arterial wall secondary to ischemic changes.
- Hypertension- Hypertension may be caused by a renal artery stenosis or precedes stenosis.
- Diabetes- High blood sugar may cause vascular and muscular diseases resulting in renal artery stenosis.
- High Cholesterol- High cholesterol causes atherosclerosis and plaque formation. High cholesterol is associated with renal artery stenosis, and Chronic renal disease.
Symptoms Of Renal Artery Stenosis (RAS)
- No Symptoms- The disease is often asymptomatic.
- Incidental Findings- The Renal Artery Stenosis is often diagnosed during abdominal image studies performed to evaluate other disease causing abdominal symptoms.
Non-Specific Symptoms of Renal Artery Stenosis (RAS):
Most of the non-specific symptoms are caused by complications like congestive heart failure and hypertension associated with Renal Artery Stenosis.
- Weakness and fatigue.
- Somnolence- sleepiness.
- Loss of appetite.
Specific Symptoms of Renal Artery Stenosis (RAS):
- Uncontrolled Hypertension-
- Congestive Heart Failure-
- End Stage Renal Disease-
- Edema feet
Diagnosis of Renal Artery Stenosis (RAS)
When there is a suspicion of a Renal Artery Stenosis, investigative tests may be ordered for confirmatory diagnosis, which may include:
- Hyperkalemia (high serum potassium)
- Low serum (blood) sodium
- Using high frequency sound wave performs Doppler study.
- The image is studied for narrowing of renal artery.
- Ultrasound of the kidneys
- CT studies and MRI
- CT Angiogram
Treatment For Renal Artery Stenosis (RAS)
Treatment of Hypertension-
- Antihypertensive Medications-
- Most effective antihypertensive medications are angiotensin inhibitors.3
- Example- Lisinopril
- Aspirin is prescribed to prevent clotting around atherosclerosis and plaque.
- Cholesterol Lowering Medications-
- Cholesterol lowering medications are prescribed to prevent formation of atherosclerosis and plaques.
- Medications prescribed are Lipitor
- Blood sugar is maintained near normal level.
- Treatment involves:
- Diet Adjustment
- Pills- Metformin
Surgery For Renal Artery Stenosis (RAS)-
- Balloon Angioplasty
- Angioplasty is a procedure in which a catheter is put inside the body via a blood vessel and guided into the area of blockage of the artery where a balloon present in the catheter is then inflated to create space in the narrowed artery.
- Stent Placement5
- Following angioplasty or balloon angioplasty Stent is placed in the narrowed lumen to open up the narrowing and maintain the larger diameter.
- Surgical Repair-
- The inner section of artery is exposed.
- The plaque and inner lining of the artery is removed.
- Bypass Procedure-
- The diseased segment of the renal artery is replaced with graft or graft is connected to abdominal artery and normal renal artery close to kidney.
1. Epidemiology and optimal management in patients with renal artery stenosis.
Piecha G1, Wiecek A, Januszewicz A.
J Nephrol. 2012 Nov-Dec;25(6):872-8.
2. Renal artery stenosis – an update.
Sattur S1, Prasad H, Bedi U, Kaluski E, Stapleton DD.
Postgrad Med. 2013 Sep;125(5):43-50.
3. Clinical effect of endovascular treatment on blood pressure and kidney function for hypertensive patients with renal artery stenosis.
He Y1, Liu Y, Wang M, Sun Y, Dong D, Yuan H, Wu X, Chong Z, Jin X.
Clin Exp Hypertens. 2013;35(5):341-6.
4. Predictive value of renal resistive index in percutaneous renal interventions for atherosclerotic renal artery stenosis.
Yuksel UC1, Anabtawi AG, Cam A, Poddar K, Agarwal S, Goel S, Kim E, Bajzer C, Gornik HL, Shishehbor MH, Tuzcu EM, Kapadia SR.
J Invasive Cardiol. 2012 Oct;24(10):504-9.
5. Stenting and medical therapy for atherosclerotic renal-artery stenosis.
Cooper CJ1, Murphy TP, Cutlip DE, Jamerson K, Henrich W, Reid DM, Cohen DJ, Matsumoto AH, Steffes M, Jaff MR, Prince MR, Lewis EF, Tuttle KR, Shapiro JI, Rundback JH, Massaro JM, D’Agostino RB Sr, Dworkin LD; CORAL Investigators.
N Engl J Med. 2014 Jan 2;370(1):13-22.