Medical KSV Practice Exam

ACE inhibitors lower angiotensin II, which normally constricts the efferent arteriole to help keep glomerular filtration pressure when kidney perfusion is reduced. In bilateral renal artery stenosis, both kidneys depend on that angiotensin II–mediated constriction to maintain GFR. Blocking it removes this compensatory mechanism, causing dilation of the efferent arteriole, a drop in intraglomerular pressure, and a risk of acute kidney injury. That hemodynamic effect makes bilateral renal artery stenosis a major contraindication to ACE inhibitors. Other options may cause side effects or be used with caution, but they are not as prohibitive as this scenario.