Study Questions: Chapter 09 Chapter 9: Renovascular Disease CHRISTOPHER J. COOPER, MD; WILLIAM R. COLYER, MD Case Study: Chapter 9 * A 35-year-old female undergoes an evaluation for drug-resistant hypertension, and on duplex ultrasound is found to have high velocities (systolic 386 cm/sec) in the distal right renal artery and a 4-cm aneurysm in the renal hilum. Which of the following is the most likely cause? Takayasu’s arteritis Atherosclerotic renal artery stenosis Williams syndrome Fibromuscular dysplasia Show answerThe correct answer is 4, Fibromuscular dysplasia. The second most common cause of renal artery stenosis is fibromuscular dysplasia, which is most frequently seen in women and younger patients. In approximately 10%, there will be a concomitant aneurysm.¹²´¹³ * In patients presenting with renal artery stenosis who undergo invasive angiography, which of the following adjunctive strategies has been associated with an improvement in blood pressure control after revascularization? Mean pressure gradient of 10 mmHg after intra-renal dopamine administration Systolic pressure gradient of 21 mmHg after 30 mg intra-arterial papaverine Systolic gradient of 20 mmHg using a 6-Fr diagnostic catheter 50% diameter stenosis by quantitative computer-assisted angiography Show answerThe correct answer is 2, Systolic pressure gradient of 21 mmHg after 30 mg intra-arterial papaverine. Several strategies have been used at the time of invasive angiography, to assess the likelihood of improving blood pressure control when stenting of atherosclerotic renal artery stenosis is performed (26, 27). Hyperemic gradients are predictive of an improvement in systolic and diastolic blood pressure with stenting. In several observational studies, it was suggested that a dopamine-induced (50-μg/kg bolus) mean gradient of 20 mmHg or a papaverine-induced (30-mg bolus)systolic gradient of 21 mmHg (26, 27) was indicative of significant renal artery stenosis, as indicated by an improvement in blood pressure. Gradients obtained with catheters may overestimate the true gradient, correlate poorly with angiographic measures of stenosis severity, (28) and have not been shown to predict treatment response. * Several randomized trials of renal artery revascularization have compared medical therapy against either balloon angioplasty or endovascular stenting. Which of the following statements is true? Stenting, but not angioplasty, improves renal function in patients with severe renal artery stenosis. Stenting prevents improves symptoms of congestive heart failure and prevents repeat hospitalizations for patients with renal artery stenosis and heart failure. Stenting improves blood pressure control when compared to medical therapy. Neither angioplasty nor stenting has been demonstrated to improve renal function when compared to medical therapy. Show answerThe correct answer is 4, Neither angioplasty nor stenting has been demonstrated to improve renal function when compared to medical therapy. Thus far, 5 randomized studies have been published that directly compared medical therapy with angioplasty or stenting. None of these studies demonstrated an improvement in blood pressure control or renal function with the only limited exception being a small sample of subjects with bilateral renal artery stenosis in the Webster study that appeared to have better blood pressure when treated with angioplasty. However, this finding has not been reported with the other studies.(5) Several case series suggest that congestive heart failure may improve after revascularization of atherosclerotic renal artery stenosis, but this has never been evaluated in the setting of a randomized study. * When used in patients with renal artery stenosis, which of the following statements concerning angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) is correct? Decrease restenosis May decrease cardiovascular events and need for dialysis Are contraindicated Paradoxically increase blood pressure Show answerThe correct answer is 2, May decrease cardiovascular events and need for dialysis. The use of ACE inhibitors and ARBs is commonly thought to be contraindicated in patients with renal artery stenosis, due to the potential for hemodynamically induced acute renal failure. However, several authors have reported better clinical outcomes in patients treated with ACE inhibitors or ARBs, including a large series reported by Hackam et al that found lower rates of dialysis and fewer cardiovascular events.(32) In general, if worsened renal function occurs after institution of an ACE inhibitor or ARB, discontinuation of the drug usually results in return of kidney function to baseline. * Which of the following statements is correct regarding surgical revascularization of the renal artery? Better outcomes when compared to balloon angioplasty Fewer complications and better outcomes during the index hospital stay for revascularization A 10% in-hospital mortality in older Americans Contraindicated in patients with coexisting complex abdominal aortic aneurysms Show answerThe correct answer is 3, A 10% in-hospital mortality in older Americans. Surgical revascularization of renal artery stenosis likely has a limited role, especially for patients with atherosclerotic renal artery stenosis, and in recent series has been associated with high (10%) in-hospital mortality rates.(43) When compared directly against balloon angioplasty, surgery and angioplasty results were found to be equivalent.(42) In patients with complex juxtarenal aneurysms, surgical renal artery revascularization still may play a role in treatment, although several recent reports suggest that branched endografts may also play a potential role in their treatment.