Editing Renal Hypertension (section)

=== Pathophysiology of Ischemic Nephropathy ===

* '''In addition to hypertension, renal artery stenosis (RAS), when hemodynamically significant, affects the entire renal functioning parenchyma and causes ischemic nephropathy'''
** '''It is unlikely that the renal damage observed in RAS is secondary to the decrement in renal blood flow (RBF) alone. The secretion of proinflammatory mediators released as a consequence of the stenosis is likely the more significant causative factor.'''
** The poststenotic renal parenchyma demonstrates a mixture of vascular sclerosis, cholesterol crystals, tubular atrophy, interstitial fibrosis with inflammatory cells, atubular glomeruli, and focal or global glomerulosclerosis
* '''The degree of stenosis necessary to produce a hemodynamically significant effect (reduction in RBF > 40%) has been estimated at 70-80%, and thus this percent of stenosis is referred to as a “critical stenosis”'''
** '''With > 80% stenosis, perfusion pressure will drop to < 70-80 mm Hg, at which point the kidney can no longer autoregulate its GFR and RBF'''
* '''Renovascular hypertension is more likely to be observed when (2):'''
*# '''≥ 70% stenosis in one or both renal arteries'''
*# '''50% stenosis with post-stenotic dilatation'''