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Renovascular Disease

Definition

Renovascular disease refers to disorders which affect the blood supply to the kidneys. In a mild form, this condition may exist on its own without causing any problems. In a more severe form, it may lead to the development or worse of high blood pressure (BP) and /or impairment in kidney function.

Epidemiology

It is difficult to know the true prevalence of renovascular disease as it may be undiagnosed in patients with high blood pressure (hypertension). Hypertension itself is often undetected in the general population and investigations vary in their accuracy to detect renovascular disease. Among patients with hypertension who underwent arteriography, (an investigation of blood vessels using x-rays and radiologic which gives the highest diagnostic accuracy) 1-6% had renovascular lesions 1-4. Autopsies (medical examinations after death) in the general population have found that 27% of people over the age of 50 have 50% narrowing of at least one renal artery. 5

Etiology

There are two main types of renal (kidney) artery disease – atherosclerotic renal artery stenosis (ARAS) in which the wall of the blood vessels become hardened and fibromuscular dysplasia (FMD). Atherosclerotic disease is most common among older men whereas fibromuscular disease predominantly affects women of childbearing age.

Rarer causes of renovascular disease include:

  • Takayasu’s arteritis (inflammation of medium-sized arteries)
  • Renal atheroembolism (blockage of smaller blood vessels in the kidney known as the arterioles, due to trapping of blood clots, cholesterol debris, etc coming from other sites, for example, diseased hearts, surgery, trauma or tumors)
  1. Atherosclerotic Renal Artery Stenosis (ARAS)
    Atherosclerosis (hardening of the arteries) accounts for approximately 90% of renovascular disease. It usually involves the beginning of the renal artery from the main distributing blood vessel, the aorta. It may also affect smaller branches of the renal artery. ARAS is associated with high morbidity and mortality because

    • It may lead to chronic kidney disease
    • It is associated with atherosclerosis elsewhere, especially in the arteries supplying blood to the limbs, heart and brain.

    Factors which increase the risk of developing ARAS include:

    • Hypertension (however up to  35% of patients with renovascular disease may have normal blood pressure )
    • Age above 50 years old 5
    • The presence of impaired kidney function.
    • Evidence of diseased blood vessels in the limbs, heart and brain.
    • Diabetes mellitus
    • Smoking
    • Family history of heart disease and blood circulatory system in the heart or kidneys
    • High levels of cholesterol and fats in the blood
  2. Fibromuscular dysplasia (FMD)
    This is a disorder of the lining of the renal arteries, the blood vessel which supplies blood to the kidney. It accounts for approximately 10% of renovascular disease. However, unlike ARAS, it rarely leads to total renal artery blockage.
    The disease is of unknown cause. Other blood vessels such as those in the brain, internal organs, and limbs may be less commonly affected.

Clinical presentation

The renovascular disease may not cause any symptoms. However, it may also present in a variety of ways. Common clinical scenarios include:

  • Onset of hypertension before 30 years old, especially without any family history
  • Hypertension developing in a patient with known co-existing atherosclerotic vascular disease elsewhere e.g. vascular diseases in the limbs, heart or brain
  • Sudden onset of hypertension after 55 years old or deterioration in BP control in a previously well-controlled patient
  • Hypertension resistant to standard medical therapy
  • Flash pulmonary oedema (episodes of sudden fluid overload in the lungs with no obvious precipitating causes)
  • Kidney failure of uncertain cause in the presence of normal urine examination
  • Kidney failure induced by a certain group of medications known as Angiotensin Converting Enzyme Inhibitors (eg. enalapril perindopril, ramipril etc) or Angiotensin Receptor Blockers which include losartan, telmisartan, valsartan, irbesartan etc.

Investigations

  1. Blood tests for estimation of kidney function and measurement of blood, sugar and cholesterol levels
  2. Urine analysis to look for the presence of abnormal red blood cells, protein leak ,etc.
  3. Imaging tests :
    • Ultrasound of the kidneys – not diagnostic but may suggest renovascular disease if there is a difference in kidney sizes > 1.5 cm. The addition of ultrasound Doppler examination will give more information but is highly subjective and dependent on the skills and expertise of the technician.
    • CT angiography – involves injection of radiologic dyes which may have adverse effects on kidney function
    • Magnetic resonance angiography (MRA) – has only been validated for disease in the early part of the renal arteries7. Gadolinium, the contrast agent used in MRA, is not recommended in severe kidney disease. Gadolinium has been associated with subsequent development of a serious disorder known as nephrogenic systemic fibrosis
    • Radionuclide scanning, a procedure which uses safe radioactive medical isotopes
    • Renal Angiography – an x-ray procedure which is considered the most definitive test. It may allow simultaneous treatment to treat the narrowed blood vessels. However carries risks of complications including
      • bleeding at the site of blood vessel puncture
      • athero-embolism
      • contrast-induced impairment of kidney function

References:

1. Correa RJ Jr, Conway J, Hoobler SW et al (1962). Renal-vascular disease as a cause of hypertension: Selection of patients for aortographic studies. J Mich.State Med.Soc 61:1361-3

2. Yamauchi H (1981).Screening hypertensive patients for surgically reversible causes-unsettled issue.heart Lung 10:261-8
3. Berglund G, Andersson O, Wilhelmson L. (1976). Prevalence of primary and secondary hypertension. Studies in a random population sample. BMJ 2:554-6

4. Rudnick KV, Sackett DL, Hirsct S et al (1977). Hypertension in a family practice. Can Med Assoc. J 117:492-7

5. Rimmer JM, Gennari J. (1993) Atherosclerotic renovascular disease and progressive renal failure. Ann Intern. Med. 118:712-19

6. Schmidt RJ et al (2009) Renovascular Hypertension. Retrieved 18th September 2012 from http://emedicine.medscape.com/article/245140

7. Spinowitz BS et al (2010) Renal Artery Stenosis. Retrieved 18th September 2012 from
http://emedicine.medscape.com/article/245023

 

Last Reviewed : 3 May 2016
Writer : Dr. Sunita Bavanandan
Accreditor : Y. Bhg. Datuk Dr. Ghazali bin Ahmad

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