Renal artery stenosis pathophysiology: Difference between revisions
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==Overview== | ==Overview== | ||
The reduction in renal blood flow secondary to renal artery stenosis stimulates [[renin]] release from the juxtaglomerular | The reduction in [[renal blood flow]] secondary to [[renal artery stenosis]] stimulates [[renin]] release from the [[Juxtaglomerular apparatus|juxtaglomerular apparatu]]<nowiki/>s through [[activation]] of the [[tubuloglomerular]] [[feedback]], [[baroreceptor]] [[reflex]], and the [[sympathetic nervous system]]. Elevated [[angiotensin II]] activities in turn cause elevation of the [[arterial]] pressure and other effects including [[aldosterone]] secretion, [[sodium]] retention, and [[left ventricular hypertrophy]] and [[remodeling]]. | ||
==Pathophysiology== | ==Pathophysiology== | ||
[[Renal artery stenosis]] means the narrowing of both [[renal]] [[arteries]] leading to the obstruction of [[blood flow]] and resulting in the stimulation of [[RAAS]]. The blood flow to the [[kidneys]] is generally greater than perfusion to any other [[organ]] and the [[GFR]] mainly depends on the [[glomerular capillary hydrostatic pressure]]. In patients with [[RAS]], the reduced [[blood]] flow to the [[kidneys]] leads to the formation of [[collateral blood vessels]] and increases secretion of [[renin]] by juxtaglomerular apparatus and activation of the renin-angiotensin-aldosterone system. Renin converts angiotensinogen to angiotensin I and then | *[[Renal artery stenosis]] means the narrowing of both [[renal]] [[arteries]] leading to the obstruction of [[blood flow]] and resulting in the stimulation of [[RAAS]]. | ||
Prolonged hypo-perfusion to the kidneys resulting in chronic stimulation and hyperplasia of the juxtaglomerular apparatus. This prolonged ischemia further leads to renal insufficiency and in turn progressive renal atrophy. | *The [[blood flow]] to the [[kidneys]] is generally greater than perfusion to any other [[organ]] and the [[GFR]] mainly depends on the [[glomerular capillary hydrostatic pressure]]. | ||
*In patients with [[RAS]], the reduced [[blood]] flow to the [[kidneys]] leads to the formation of [[collateral blood vessels]] and increases secretion of [[renin]] by juxtaglomerular apparatus<ref name="pmid19219002">{{cite journal |vauthors=Gomez RA, Sequeira Lopez ML |title=Who and where is the renal baroreceptor?: the connexin hypothesis |journal=Kidney Int |volume=75 |issue=5 |pages=460–2 |date=March 2009 |pmid=19219002 |pmc=3025775 |doi=10.1038/ki.2008.536 |url=}}</ref>and activation of the [[renin-angiotensin-aldosterone system]]<ref name="Garovic-2005">{{Cite journal | last1 = Garovic | first1 = VD. | last2 = Textor | first2 = SC. | title = Renovascular hypertension and ischemic nephropathy. | journal = Circulation | volume = 112 | issue = 9 | pages = 1362-74 | month = Aug | year = 2005 | doi = 10.1161/CIRCULATIONAHA.104.492348 | PMID = 16129817 }}</ref> | |||
*Renin converts angiotensinogen to angiotensin I and then further gets converted to [[Angiotensin II]] with the help of ACE | |||
*This [[angiotensin II]] directly causes [[vasoconstriction]] and also increases [[aldosterone]] which results in the retention of [[sodium]] and [[water]] thus leads to the development of [[renovascular hypertension]] that is also called [[secondary hypertension]]. | |||
*Prolonged [[hypo-perfusion]] to the [[kidneys]] resulting in chronic stimulation and [[hyperplasia]] of the [[juxtaglomerular apparatus]]. This prolonged [[ischemia]] further leads to [[renal insufficiency]] and in turn [[progressive renal atrophy]]<ref name="pmid15284283">{{cite journal |vauthors=Textor SC |title=Ischemic nephropathy: where are we now? |journal=J Am Soc Nephrol |volume=15 |issue=8 |pages=1974–82 |date=August 2004 |pmid=15284283 |doi=10.1097/01.ASN.0000133699.97353.24 |url=}}</ref>. | |||
== Pathogenesis == | |||
[[Glomerular filtration rate]] (GFR) is auto-regulated with the help of [[angiotensin II]] and numerous other modulators. The [[GFR]] gets affected when the [[renal]] [[perfusion]] drops below 70 mmHg<ref name="urlRenal Artery Stenosis | NIDDK">{{cite web |url=https://www.niddk.nih.gov/health-information/kidney-disease/renal-artery-stenosis#rasrvh |title=Renal Artery Stenosis | NIDDK |format= |work= |accessdate=}}</ref>. the apparent change in [[GFR]] is observed once the [[arterial]] lumen narrows by more than 50%. Numerous studies reported that [[GFR]] is reduced when altogether there is a reduction in [[renal]] [[perfusion pressure]] by more than 40% and a reduction in mean [[renal blood flow]] by 30%. However, even after this, the [[kidneys]] cortex and [[medulla]] can adapt without the development of severe [[hypoxia]]. So early disease can be managed with the medical approach and that can prevent the development of progressive function loss and [[fibrosis]]. But in cases with more significant [[stenosis]] around 70-80%, there is the development of apparent [[cortical hypoxia]] and this [[hypoxia]] further leads to the [[rarefaction]] of [[microvessels]] and ultimately leads to the development of [[interstitial fibrosis]]<ref name="pmid15284283">{{cite journal |vauthors=Textor SC |title=Ischemic nephropathy: where are we now? |journal=J Am Soc Nephrol |volume=15 |issue=8 |pages=1974–82 |date=August 2004 |pmid=15284283 |doi=10.1097/01.ASN.0000133699.97353.24 |url=}}</ref>. Therefore the loss of [[renal]] function and progressive [[renal disease]]. Eventually, it becomes [[irreversible]] and [[restoration]] of [[blood flow]] to the [[kidneys]] will not help in getting back the [[kidney]] [[functions]]. | |||
[[Image:Renal artery stenosis diagram 001.gif|200px|Illustration of renal artery stenosis]] | [[Image:Renal artery stenosis diagram 001.gif|200px|Illustration of renal artery stenosis]] | ||
Latest revision as of 07:29, 8 April 2021
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Shivam Singla, M.D.[2]
Overview
The reduction in renal blood flow secondary to renal artery stenosis stimulates renin release from the juxtaglomerular apparatus through activation of the tubuloglomerular feedback, baroreceptor reflex, and the sympathetic nervous system. Elevated angiotensin II activities in turn cause elevation of the arterial pressure and other effects including aldosterone secretion, sodium retention, and left ventricular hypertrophy and remodeling.
Pathophysiology
- Renal artery stenosis means the narrowing of both renal arteries leading to the obstruction of blood flow and resulting in the stimulation of RAAS.
- The blood flow to the kidneys is generally greater than perfusion to any other organ and the GFR mainly depends on the glomerular capillary hydrostatic pressure.
- In patients with RAS, the reduced blood flow to the kidneys leads to the formation of collateral blood vessels and increases secretion of renin by juxtaglomerular apparatus[1]and activation of the renin-angiotensin-aldosterone system[2]
- Renin converts angiotensinogen to angiotensin I and then further gets converted to Angiotensin II with the help of ACE
- This angiotensin II directly causes vasoconstriction and also increases aldosterone which results in the retention of sodium and water thus leads to the development of renovascular hypertension that is also called secondary hypertension.
- Prolonged hypo-perfusion to the kidneys resulting in chronic stimulation and hyperplasia of the juxtaglomerular apparatus. This prolonged ischemia further leads to renal insufficiency and in turn progressive renal atrophy[3].
Pathogenesis
Glomerular filtration rate (GFR) is auto-regulated with the help of angiotensin II and numerous other modulators. The GFR gets affected when the renal perfusion drops below 70 mmHg[4]. the apparent change in GFR is observed once the arterial lumen narrows by more than 50%. Numerous studies reported that GFR is reduced when altogether there is a reduction in renal perfusion pressure by more than 40% and a reduction in mean renal blood flow by 30%. However, even after this, the kidneys cortex and medulla can adapt without the development of severe hypoxia. So early disease can be managed with the medical approach and that can prevent the development of progressive function loss and fibrosis. But in cases with more significant stenosis around 70-80%, there is the development of apparent cortical hypoxia and this hypoxia further leads to the rarefaction of microvessels and ultimately leads to the development of interstitial fibrosis[3]. Therefore the loss of renal function and progressive renal disease. Eventually, it becomes irreversible and restoration of blood flow to the kidneys will not help in getting back the kidney functions.
References
- ↑ Gomez RA, Sequeira Lopez ML (March 2009). "Who and where is the renal baroreceptor?: the connexin hypothesis". Kidney Int. 75 (5): 460–2. doi:10.1038/ki.2008.536. PMC 3025775. PMID 19219002.
- ↑ Garovic, VD.; Textor, SC. (2005). "Renovascular hypertension and ischemic nephropathy". Circulation. 112 (9): 1362–74. doi:10.1161/CIRCULATIONAHA.104.492348. PMID 16129817. Unknown parameter
|month=ignored (help) - ↑ 3.0 3.1 Textor SC (August 2004). "Ischemic nephropathy: where are we now?". J Am Soc Nephrol. 15 (8): 1974–82. doi:10.1097/01.ASN.0000133699.97353.24. PMID 15284283.
- ↑ "Renal Artery Stenosis | NIDDK".