Snapshot A 59-year-old man with a history of hypertension presents to his primary care physician for blood pressure management. He has tried lisinopril, hydrochlorothiazide, and losartan, and had minimal effect. He has a strong family history of cardiovascular disease. Physical examination is notable for a bruit in the right flank. Routine bloodwork shows an elevated creatinine. Preparations are made for a doppler ultrasound of the renal arteries. Introduction Clinical definition narrowing of one or both renal arteries this often causes renovascular hypertension grade 1 – RAS (Renal artery stenosis) with no clinical symptoms grade 2 – RAS with controlled hypertension grade 3 – RAS with resistant hypertension, abnormal renal function, or volume overload Epidemiology Prevalence 7% in the United States present in up to 1/3 of patients with malignant or resistant hypertension Demographics atherosclerotic disease patients > 50 years of age fibromuscular dysplasia young women Risk factors atherosclerosis and its risk factors (e.g., smoking and fatty diet) fibromuscular dysplasia kidney transplant patients high calcium or phosphorous levels high low-density lipoprotein cholesterol levels Etiology Pathophysiology narrowing of artery lumen due to atherosclerosis fibromuscular dysplasia narrowed arteries lead to reduced renal perfusion reduced perfusion leads to activation of renin-angiotensin system increased renin → hypertension, hypokalemia, and hypernatremia bilateral renal stenosis can lead to volume overload heart failure pulmonary edema Associated conditions other manifestations of atherosclerotic disease carotid artery disease lower extremity artery disease coronary heart disease Presentation History hypertension before 30 years of age consider fibromuscular dysplasia in young women with abrupt onset of hypertension resistant or malignant hypertension worsening renal function after taking an ACE inhibitor or angiotensin receptor blocking (ARB) agent may indicate bilateral RAS because ACE inhibitors and ARBs further decrease glomerular filtration rate and worsens renal function sudden unexplained volume overload (heart failure or pulmonary edema) Symptoms primary symptoms hypertension Physical exam extremities may have edema if volume overloaded abdomen abdominal or flank bruit through systole and diastole Imaging Ultrasound indications often initial imaging in those < 60 years of age in patients with suspected RAS sensitivity and specificity sensitivity 88-93% specificity 82-89% CT angiography indications in patients with normal renal function and suspected RAS sensitivity and specificity sensitivity 90% specificity 94% MR angiography in patients with renal insufficiency indications in patients with renal insufficiency and suspected RAS sensitivity and specificity sensitivity 75-97% specificity 64-93% Invasive catheter angiography indications only indicated if high suspicion of disease but inconclusive imaging or if revascularization is planned gold standard for diagnosis Studies Labs serum creatinine to assess renal function elevated creatinine may indicate atherosclerosis-associated RAS normal creatinine may indicate fibromuscular dysplasia-associated RAS urine protein to assess renal function typically below nephrotic range (< 3.5 g in 24 hours) Histology fibromuscular dysplasia medial fibroplasia Diagnostic criteria reduction of diameter of > 60% string-of-beads appearance on angiography in fibromuscular dysplasia Differential Essential hypertension typically responsive to therapy Primary hyperaldosteronism high levels of aldosterone Obstructive sleep apnea lethargy and fatigue Treatment Medical ACE-inhibitors or ARBs indications persistent hypertension in patients with RAS contraindicated in bilateral RAS or RAS in patients with single kidney calcium channel blockers or β-blockers given if patients do not respond to ACE-inhibitors or ARBs manage lipid disorders with statins Operative revascularization indications severe complications of RAS unexplained heart failure unexplained pulmonary edema chronic kidney disease inadequately controlled hypertension outcomes may not improve outcomes in those with atherosclerotic RAS cures up to 58% of hypertension in patients with fibromuscular dysplasia-associated RAS complications contrast-induced acute kidney injury or allergic reaction (< 3%) bleeding, hematoma, or arteriovenous fistula Complications Renal dysfunction can progress to end-stage renal disease incidence 4% in one study of 68 adults over 39 months treatment dialysis and kidney transplant Prognosis Prognostic variable negative elevated serum creatinine comorbid heart disease comorbid chronic obstructive pulmonary disease (COPD) Survival with treatment 91% at 1 year 67% at 5 years 41% at 10 years