Renal artery stenosis

Renal artery stenosis (RAS) is the narrowing of one or both of the renal arteries, most often caused by atherosclerosis or fibromuscular dysplasia. This narrowing of the renal artery can impede blood flow to the target kidney, resulting in renovascular hypertension – a secondary type of high blood pressure. Possible complications of renal artery stenosis are chronic kidney disease and coronary artery disease.[1]

Renal artery stenosis
SpecialtyNephrology
Risk factorsSmoking, High blood pressure[1]
Diagnostic methodCaptopril challenge test, Doppler ultrasound[2][3]
TreatmentACE inhibitors[1]

Signs and symptoms

Most cases of renal artery stenosis are asymptomatic, and the main problem is high blood pressure that cannot be controlled with medication.[4] Decreased kidney function may develop if both kidneys do not receive adequate blood flow, furthermore some people with renal artery stenosis present with episodes of flash pulmonary edema.[5]

Cause

Renal artery stenosis is most often caused by atherosclerosis which causes the renal arteries to harden and narrow due to the build-up of plaque. This is known as atherosclerotic renovascular disease.This accounts for about 90% of cases with most of the rest due to fibromuscular dysplasia.[6] Fibromuscular dysplasia is the predominant cause in young patients, usually females under 40 years of age.[7]

Pathophysiology

The pathophysiology of renal artery stenosis leads to changes in the structure of the kidney that are most noticeable in the tubular tissue.[8] If the stenosis is longstanding and severe, the glomerular filtration rate in the affected kidneys never recovers and (prerenal) kidney failure is the result.

Changes include:[8]

  • Fibrosis
  • Tubular cell size (decrease)
  • Thickening of Bowman capsule
  • Tubulosclerosis
  • Glomerular capillary tuft (atrophy)

Diagnosis

The diagnosis of renal artery stenosis can use many techniques to determine if the condition is present, a clinical prediction rule is available to guide diagnosis.[9]

Among the diagnostic techniques are:

The specific criteria for renal artery stenosis on Doppler are an acceleration time of greater than 70 milliseconds, an acceleration index of less than 300 cm/sec² and a velocity ratio of the renal artery to aorta of greater than 3.5.[14]

Treatment
A diuretic (Hydrochlorothiazide)

Atherosclerotic renal artery stenosis

It is initially treated with medications, including diuretics, and medications for blood pressure control.[8] When high-grade renal artery stenosis is documented and blood pressure cannot be controlled with medication, or if renal function deteriorates, surgery may be resorted to. The most commonly used procedure is a minimally-invasive angioplasty with or without stenting. It is unclear if this approach yields better results than the use of medications alone.[15] It is a relatively safe procedure.[15] If all else fails and the kidney is thought to be worsening hypertension and revascularization with angioplasty or surgery does not work, then surgical removal of the affected kidney (nephrectomy) may significantly improve high blood pressure.[16]

Fibromuscular dysplasia

Angioplasty with or without stenting is the best option for the treatment of renal artery stenosis due to fibromuscular dysplasia.[17]

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See also

References
  1. "Renal Artery Stenosis". National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved 2015-08-17.
  2. Granata, A.; Fiorini, F.; Andrulli, S.; Logias, F.; Gallieni, M.; Romano, G.; Sicurezza, E.; Fiore, C.E. (2009-10-12). "Doppler ultrasound and renal artery stenosis: An overview". Journal of Ultrasound. 12 (4): 133–143. doi:10.1016/j.jus.2009.09.006. ISSN 1971-3495. PMC 3567456. PMID 23397022.
  3. Ong, Yong Yau (2005-01-01). A Clinical Approach to Medicine. World Scientific. ISBN 9789812560735.
  4. "Renovascular hypertension: MedlinePlus Medical Encyclopedia". www.nlm.nih.gov. Retrieved 2015-08-17.
  5. Messerli, Franz H.; Bangalore, Sripal; Makani, Harikrishna; Rimoldi, Stefano F.; Allemann, Yves; White, Christopher J.; Textor, Stephen; Sleight, Peter (2011-03-15). "Flash pulmonary oedema and bilateral renal artery stenosis: the Pickering Syndrome". European Heart Journal. 32 (18): 2231–5. doi:10.1093/eurheartj/ehr056. ISSN 0195-668X. PMID 21406441.
  6. "RenalArtery Stenosis" (PDF). NIH. National Institute of Health. Retrieved 1 August 2016.
  7. "Fibromuscular Dysplasia: Practice Essentials, Background, Pathophysiology". 2018-09-19. Cite journal requires |journal= (help)
  8. "Renal Artery Stenosis: Background, Pathophysiology, Etiology". 2018-12-14. Cite journal requires |journal= (help)
  9. Steyerberg, Ewout (2008-12-16). Clinical Prediction Models: A Practical Approach to Development, Validation, and Updating. Springer Science & Business Media. ISBN 9780387772448.
  10. Protasiewicz, Marcin; Kądziela, Jacek; Początek, Karol; Poręba, Rafał; Podgórski, Maciej; Derkacz, Arkadiusz; Prejbisz, Aleksander; Mysiak, Andrzej; Januszewicz, Andrzej (2013-11-01). "Renal artery stenosis in patients with resistant hypertension". The American Journal of Cardiology. 112 (9): 1417–1420. doi:10.1016/j.amjcard.2013.06.030. ISSN 1879-1913. PMID 24135303. – via ScienceDirect (Subscription may be required or content may be available in libraries.)
  11. Talley, Nicholas Joseph; O'Connor, Simon (2013-09-20). Clinical Examination: A Systematic Guide to Physical Diagnosis. Elsevier Health Sciences. ISBN 9780729541473.
  12. Sam, Amir H.; James T.H. Teo (2010). Rapid Medicine. Wiley-Blackwell. ISBN 978-1405183239.
  13. Attenberger, Ulrike I.; Morelli, John N.; Schoenberg, Stefan O.; Michaely, Henrik J. (2011-11-15). "Assessment of the kidneys: magnetic resonance angiography, perfusion and diffusion". Journal of Cardiovascular Magnetic Resonance. 13 (1): 70. doi:10.1186/1532-429X-13-70. ISSN 1532-429X. PMC 3228749. PMID 22085467.
  14. Granata, A.; Fiorini, F.; Andrulli, S.; Logias, F.; Gallieni, M.; Romano, G.; Sicurezza, E.; Fiore, C. E. (1 December 2009). "Doppler ultrasound and renal artery stenosis: An overview". Journal of Ultrasound. 12 (4): 133–143. doi:10.1016/j.jus.2009.09.006. ISSN 1971-3495. PMC 3567456. PMID 23397022.
  15. Jenks, S; Yeoh, SE; Conway, BR (5 December 2014). "Balloon angioplasty, with and without stenting, versus medical therapy for hypertensive patients with renal artery stenosis". The Cochrane Database of Systematic Reviews. 12 (12): CD002944. doi:10.1002/14651858.CD002944.pub2. PMC 7138037. PMID 25478936.
  16. Fine, Richard N.; Webber, Steven A.; Harmon, William E.; Kelly, Deirdre; Olthoff, Kim M. (2009-04-08). Pediatric Solid Organ Transplantation. John Wiley & Sons. ISBN 9781444312737.
  17. Chrysant, Steven G.; Chrysant, George S. (2014-02-21). "Treatment of hypertension in patients with renal artery stenosis due to fibromuscular dysplasia of the renal arteries". Cardiovascular Diagnosis and Therapy. 4 (1): 36–43. doi:10.3978/j.issn.2223-3652.2014.02.01. PMC 3943779. PMID 24649423.

Further reading
Classification
External resources
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