Renal Artery Stenosis: Pathogenesis and clinical findings
Atherosclerosis: A collection of inflammatory cells, lipids, & Fibromuscular Dysplasia: A rare vascular condition characterized by
fibrous connective tissue deposits on the renal artery wall abnormal cellular growth in arterial walls, especially renal & carotid arteries
Narrowing (stenosis) of the renal artery
Renal Artery Stenosis can be unilateral or bilateral
Authors: Samin Dolatabadi, Yan Yu* Reviewers: Meena Assad, Jessica Krahn Timothy Fu, Brooke Fallis, Juliya Hemmett* * MD at time of publication
↓ Pressure perfusing the kidney
↑ RAAS (renin-angiotensin- aldosterone system) activation
↓ pressure gradient in glomerulus
↓ Glomerular filtration rate (GFR)
↑ Secretion of aldosterone
Turbulent blood flow through area of stenosis
Abdominal bruit on side of affected kidney(s)
↑ Secretion of Angiotensin IIà ↑ Systemic vasoconstriction
Hypertension
↑ Expression of epithelial sodium channels in cortical collecting duct
↑ Blood volume within volume- constrained space of blood vessels
↓ Renal blood flowà ischemic renal injury
Atrophy and fibrosis of affected kidney(s)
Unilateral stenosis à Kidney size asymmetry (≥1.5cm difference)
↓ Positively charged Na+ in lumen à Electronegative lumen compared to the interstitial/tubular epithelial cells
K+ follows the electrical gradient and is secreted into the electronegative tubular lumen
↓ Serum K+ concentration
Hypokalemia
*Note: In unilateral renal artery stenosis, the contralateral (normal) kidney can compensate for the increase in renal perfusion pressure caused by hypertension by increasing sodium excretion (pressure natriuresis), preventing flash pulmonary edema.
↑ NHE3 (Sodium Hydrogen Exchanger 3) activity in proximal collecting tubule
↑ Na+ and water reabsorption from renal tubular lumen into blood vessels
Chronic left ventricle pressure overload àLeft ventricle hypertrophy (see Left Heart Failure: Pathogenesis Slide)
Systolic dysfunction → ↓ left ventricle stroke volume
Normally, ↑ in renal perfusion pressureà↑ Na+ excretion and water loss (pressure natriuresis)
In bilateral renal artery stenosis*, ↓ GFRàinability for kidney to ↑ renal Na+ & water excretion à volume overload
Acute increase in afterload or preload → sudden ↑ in left ventricular filling pressures → blood backup into lungs
Pulmonary vasculature hypertension → ↑ fluid filtration across the pulmonary endothelium into interstitium and alveolar spaces
Flash (rapid onset) pulmonary edema
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published December 30, 2021 on www.thecalgaryguide.com