Renal Artery stenosis

Question 1

Define Renal artery stenosis

Answer 1

RAS is the narrowing of the renal artery lumen-considered significant when over 50% occluded
causes ischemic nephropathy and renovascular hypertension

Question 2

Aetiology and risk factors of Renal artery stenosis

Answer 2

atherosclerotic causes:
dyslipidemia, diabetes, smoking
Fibromuscular causes:
Medial fibroplasia-caused by smoking
Other:
transplant, aneurysm, trauma

Reduced perfusion of the kidney causes hyper activation of the RAAS system, to increase blood flow (by hypertension)
AngII also causes fibroblast activation resulting in medial fibroplasia
arhterosclerositc RAS-proximal third of artery
Fibroplasia-any part, or multifocal (beards on a string)

artherosclerotic RAS in 90% of RAS
can be bilateral, unilateral, proximal, distal

Moderate-50-70
severe-70-99
total-100%

Risk factors
Female
Older age for arthero
Younger for fibroplasia
Smoking, diabetes,  dyslipdemia
HTN with no FHx
other artery disease
Unexplained heart failure

Question 3

Epidiemology of Renal artery stenosis

Answer 3

Prevalence of 0.5% in hypertensive patients

Mainly artheroslcerotic RAS

Question 4

Signs and Sx of Renal artery stenosis

Answer 4

severe, progressive and resistance Hypertension
Young onset-fibroplasia-always think as cause for young HTN
Older-artherosclerotic

spontaneous unexplained pulmonary oedema or AKI/loss of kidney function

and risk factors (perivascular disease, artery disease, diabetes, smoking, atherosclerosis, etc)

examination-
Renal bruits with stethoscope/abdo bruits
Other bruits-often associated with PVD
Pulm Oedema signs

Hx or Sx of hypokalemia

Question 5

Investigations of Renal artery stenosis

Answer 5

Creatinine-elevated (GFR low)
Potassium-low (RAAS activation)

Urinanalysis-find cause-diabetetic nephropathy-causes proteinuria. glycuria

aldosterone/renin ratio-normal-under 20-eliminate Conn’s

Imaging-duplex ultrasound
Contrast MR angiopathy