<prompt> Renal aery stenosis is caused by all exceptAtherosclerosisFibromuscular dysplasiaTakayasu aeritisBuergers disease  <response>: Renal aery stenosis: aCauses- Atherosclerotic diseasemost common cause - Fibromuscular DysplasiaFMD - Extrinsic compression of the vessel a It is considered a specifically treatable secondary cause of hypeension a Pathogenesis: Critical levels of stenosis - reduction in perfusion pressure - Activation of the renin-angiotensin system and sympathetic adrenergic pathways - systemic hypeensiona LVH and renal fibrosis later stages a Renal aery stenosis is also labelled ischemic nephropathy; ARAS and SHT tend to affect both the poststenotic and contralateral kidneys, reducing overall GFR in ARAS Fibromuscular DysplasiaFMD Atherosclerotic renal aery stenosis ARAS - Occurs in 3-5 of normal subjects - Presents clinically with hypeension in younger individuals age 15-50, most often women. - lesions are frequently bilateral and, tend to affect more distal poions of the renal aery. - Usually does not affect kidney function, but may cause total occlusion and can be associated with renal aery aneurysms - Common in the general population, prevalence increases with age and in patients with CAD, PAD. - obstruction most commonly at the origin - If untreated may progress to total occlusion in 50 cases - It is a strong predictor of morbidity- and moality-related cardiovascular events a Evaluation: -Captopril renography with technetium 99m Tc meiatide 99mTc MAG3 a Normal study excludes renovascular hypeension-Nuclear imaging with technetium meiatide or technetium-labelled pentetic acid DTPAa Allows calculation of single-kidney GFR -Duplex ultrasonographyaInexpensive, non-invasive - Magnetic resonance angiographyaExpensive; not nephrotoxic but gadolinium toxicity excludes use in GFR30 mlmin, unable to visualize stented vessels -computed tomographic angiographyaExpensive, potentially nephrotoxic, stents do not cause aefacts -Intra-aerial angiographyaConsidered gold standard for diagnosis of large vessel disease; Expensive, associated risk of atheroemboli, contrast toxicity, procedure-related complications, e.g., dissection a Treatment: -blockade of the renin-angiotensin system, attainment of goal blood pressures, cessation of tobacco, statins, and aspirin -percutaneous transluminal renal angioplasty PTRA for FMD, endovascular stenting or surgical renal revascularizationfor ARAS Ref: Harrisons 18e p2048 