Screening for carotid and renal artery stenoses in patients with aortoiliac disease

Evaluating Short-Term and Long-Term Risks Associated with Renal Artery Stenosis Position and Severity: A Hemodynamic Study

Background: Moderate renal artery stenosis (50-70%) may lead to uncontrolled hypertension and eventually cause irreversible damage to renal function. However, the clinical criteria for interventional treatment are still ambiguous in this condition. This study investigated the impact of the position and degree of renal artery stenosis on hemodynamics near the renal artery to assess the short-term and long-term risks associated with this disease. Methods: Calculation models with different degrees of stenosis (50%, 60%, and 70%) located at different positions in the right renal artery were established based on the computed tomography angiography (CTA) of a personalized case. And computational fluid dynamics (CFD) was used to analyze hemodynamic surroundings near the renal artery. Results: As the degree of stenosis increases and the stenosis position is far away from the aorta, there is a decrease in renal perfusion. An analysis of the wall shear stress (WSS)-related parameters indicated areas near the renal artery (downstream of the stenosis and the entrance of the right renal artery) with potential long-term risks of thrombosis and inflammation. Conclusion: The position and degree of stenosis play a significant role in judging short-term risks associated with renal perfusion. Moreover, clinicians should consider not only short-term risks but also independent long-term risk factors, such as certain regions of 50% stenosis with adequate renal perfusion may necessitate prompt intervention.

A Systematic Review Supporting the Society for Vascular Surgery Guidelines on the Management of Carotid Artery Disease

BACKGROUND

To support the development of guidelines on the management of carotid disease, a writing committee from the Society for Vascular Surgery has commissioned this systematic review.

METHODS

We searched multiple data bases for studies addressing 5 questions: medical management vs. carotid revascularization (CEA) in asymptomatic patients, CEA vs. CAS in symptomatic low surgical risk patients, the optimal timing of revascularization after acute stroke, screening high risk patients for carotid disease, and the optimal sequence of interventions in patients with combined coronary and carotid disease. Studies were selected and appraised by pairs of independent reviewers. Meta-analyses were performed when feasible.

RESULTS

Medical management compared to carotid interventions in asymptomatic patients was associated with better early outcome during the first 30 days. However, CEA was associated with significantly lower long-term rate of stroke/death at 5 years. In symptomatic low risk surgical patients, CEA was associated with lower risk of stroke, but a significant increase in MI compared to CAS during the first 30 days. When the long-term outcome of transfemoral CAS vs. CEA in symptomatic patients were examined using pre-planned pooled analysis of individual patient data from four randomized trials, the risk of death or stroke within 120 days of the index procedure was 5.5% for CEA and 8.7% for CAS, which lends support that over the long-term, CEA has superior outcome than transfemoral CAS. When managing acute stroke, the comparison of CEA during the first 48 hours to that between day 2 and day14 did not reveal a statistically significant difference on outcomes during the first 30 days. Registry data show good results with CEA performed in the first week, but not within the first 48 hours. A single risk factor, aside from PAD, was associated with low carotid screening yield. Multiple risk factors greatly increase the yield of screening. Evidence on the timing of interventions in patients with combined carotid and coronary disease was sparse and imprecise. Patients without carotid symptoms, who had the carotid intervention first, compared to a combined carotid intervention and CABG, had better outcomes.

CONCLUSIONS

This updated evidence summary will support the SVS clinical practice guidelines for commonly raised clinical scenarios. CEA was superior to medical therapy in long-term prevention of stroke/death over medical therapy. CEA was also superior to transfemoral CAS in minimizing long-term stroke/death for symptomatic low risk surgical patients. CEA should optimally be performed between 2-14 days from the onset of acute stroke. Having multiple risk factors increases the value of carotid screening.

SOCIETY FOR VASCULAR SURGERY CLINICAL PRACTICE GUIDELINES FOR MANAGEMENT OF EXTRACRANIAL CEREBROVASCULAR DISEASE

Management of carotid bifurcation stenosis in stroke prevention has been the subject of extensive investigations, including multiple randomized controlled trials. The proper treatment of patients with carotid bifurcation disease is of major interest to vascular surgeons and other vascular specialists. In 2011, the Society for Vascular Surgery published guidelines for treatment of carotid artery disease. At the time, several randomized trials, comparing carotid endarterectomy (CEA) and carotid artery stenting (CAS), were published. Since that publication, several studies and a few systematic reviews comparing CEA and CAS have been published, and the role of medical management has been re-emphasized. The current publication updates and expands the 2011 guidelines with specific emphasis on five areas: is carotid endarterectomy recommended over maximal medical therapy in low risk patients; is carotid endarterectomy recommended over trans-femoral carotid artery stenting in low surgical risk patients with symptomatic carotid artery stenosis of >50%; timing of carotid Intervention in patients presenting with acute stroke; screening for carotid artery stenosis in asymptomatic patients; and optimal sequence for intervention in patients with combined carotid and coronary artery disease. A separate implementation document will address other important clinical issues in extracranial cerebrovascular disease. Recommendations are made using the GRADE (Grades of Recommendation Assessment, Development and Evaluation) approach, as has been done with other Society for Vascular Surgery guidelines. The committee recommends CEA as the first-line treatment for symptomatic low risk surgical patients with stenosis of 50% to 99% and asymptomatic patients with stenosis of 70% to 99%. The perioperative risk of stroke and death in asymptomatic patients must be <3% to ensure benefit for the patient. In patients with recent stable stroke (modified Rankin 0-2), carotid revascularization is considered appropriate in symptomatic patients with greater than 50% stenosis and is recommended and performed as soon as the patient is neurologically stable after 48 hours but definitely before 14 days of onset of symptoms. In the general population, screening for clinically asymptomatic carotid artery stenosis in patients without cerebrovascular symptoms or significant risk factors for carotid artery disease is not recommended. In selected asymptomatic patients who are at increased risk for carotid stenosis, we suggest screening for clinically asymptomatic carotid artery stenosis as long as the patients would potentially be fit for and willing to consider carotid intervention if significant stenosis is discovered. In patients with symptomatic carotid stenosis 50-99%, who require both CEA and CABG, we suggest CEA before or concomitant with CABG to potentially reduce the risk of stroke and stroke/death. The sequencing of the intervention depends on clinical presentation and institutional experience.

Extrarenal atherosclerotic disease blunts renal recovery in patients with renovascular hypertension

BACKGROUND

Atherosclerotic renovascular disease (ARVD) is associated with high rates of coronary events and predicts mortality among patients with coronary artery disease (CAD). However, the impact of coronary atherosclerosis on renal outcomes after revascularization of ARVD is unclear. We hypothesized that CAD negatively impacts renal functional outcomes among patients with ARVD undergoing renal artery revascularization.

METHODS

Patients with ARVD who underwent echocardiography at Mayo Clinic, Rochester, Minnesota, USA between 2004 and 2012 were identified retrospectively and included if they had ejection fraction more than 50%. Renal and overall outcomes were compared among atherosclerotic renovascular disease patients with coronary artery disease (ARVD-C, n = 75) and without coronary artery disease (ARVD, n = 56), within 1 year from initial revascularization and included blood pressure control, renal function, and incident cardiovascular/cerebrovascular events.

RESULTS

Degree of renal artery stenosis was similar in both groups. ARVD-C had higher prevalence of diabetes, peripheral artery disease (PAD), and cerebrovascular disease, and lower baseline renal function. Risk of developing end-stage renal disease was higher in ARVD-C (11 vs. 2%, P = 0.05). Despite better control of blood pressure and cholesterol levels, renal function postrevascularization worsened in 15% of ARVD-C compared with 2% of ARVD (P = 0.01). Differences in clinical outcomes remained statistically significant after adjustment for covariables, including sex, baseline blood pressure, renal function, underlying diabetes, cholesterol levels, and medications. Similar differences in clinical outcomes were also associated with PAD and cerebrovascular disease.

CONCLUSION

CAD in patients with ARVD is a predictor of worse outcomes after renal revascularization, likely reflecting diffuse atherosclerotic disease. Further studies are needed to develop strategies to manage patients with vascular comorbidities and improve their outcomes.

From the 1990s to CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) trial results and beyond: does stenting have a role in ischemic nephropathy?

The prevalence of atherosclerotic renal artery stenosis is high, ∼7% in individuals older than 65 years and ∼50% in patients with diffuse arterial disease, and it is increasingly frequent in an aging population. About 10% to 15% of atherosclerotic renal artery stenosis cases lead to the development of resistant hypertension and/or ischemic nephropathy. The management of ischemic nephropathy may include medical therapy and/or revascularization. In the past, revascularization required surgical bypass or endarterectomy, accompanied by the morbidity and mortality associated with a major surgical procedure. During the last few decades, less invasive endovascular procedures such as percutaneous transluminal renal artery angioplasty with stent placement have become available. At the same time, new antihypertensive and cardiovascular drugs have been developed, which may preclude revascularization, at least in some cases. The indications of each of these therapeutic options have changed over time. This review offers a temporal perspective on the course of technical and scientific advances and the accompanying change in clinical practice for the treatment of ischemic nephropathy. The latest randomized clinical trials, including the CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) trial, the largest on the subject, as well as a meta-analysis of these studies, have indicated that the best approach is medical therapy alone. There is evidence that revascularization brings no additional benefit, at least in low-risk and stable atherosclerotic renal artery stenosis. High-risk patients, especially those with recurrent flash pulmonary edema, could benefit from percutaneous transluminal renal artery angioplasty and stent placement, but there is no definitive evidence and the treatment choice should take into account the risks and potential benefits of the procedure.

Carotid stenosis: what is the high-risk population?

OBJECTIVE

Prevention is the best treatment for cerebrovascular disease, which is why early diagnosis and the immediate treatment of carotid stenosis contribute significantly to reducing the incidence of stroke. Given its silent nature, 80% of stroke cases occur in asymptomatic individuals, emphasizing the importance of screening individuals with carotid stenosis and identifying high-risk groups for the disease. The aim of this study was to determine the prevalence and the most frequent risk factors for carotid stenosis.

METHODS

A transversal study was conducted in the form of a stroke prevention campaign held on three nonconsecutive Saturdays. During the sessions, carotid stenosis diagnostic procedures were performed for 500 individuals aged 60 years or older who had systemic arterial hypertension and/or diabetes mellitus and/or coronary heart disease and/or a family history of stroke.

RESULTS

The prevalence of carotid stenosis in the population studied was 7.4%, and the most frequent risk factors identified were mean age of 70 years, carotid bruit, peripheral obstructive arterial disease, coronary insufficiency and smoking. Independent predictive factors of carotid stenosis include the presence of carotid bruit or peripheral obstructive arterial disease [corrected] and/or coronary insufficiency.

CONCLUSIONS

The population with peripheral obstructive arterial disease [corrected] and/or coronary insufficiency and carotid bruit should undergo routine screening for carotid stenosis.

Prevalence of significant carotid artery stenosis in Iranian patients with peripheral arterial disease

BACKGROUND

Generalized screening for carotid artery stenosis with carotid duplex ultrasonography in patients with peripheral arterial disease is controversial.

OBJECTIVES

The aim of the present study was to determine the prevalence of significant internal carotid artery (ICA) stenosis in a group of Iranian patients with peripheral arterial disease.

METHODS

We prospectively screened 120 patients with a known diagnosis of peripheral vascular disease for carotid artery stenosis. Based on the angiographic assessment of abdominal aorta and arteries of the lower extremities, patients with stenosis greater than 70% in the lower extremity arteries were included. A group of healthy individuals aged ≥ 50 years was recruited as a control. Risk factors for atherosclerosis including smoking, diabetes mellitus, hyperlipidemia, ischemic heart disease, and cerebrovascular disease were recorded. Common carotid arteries (CCAs) and the origins of the internal and external arteries were scanned with B-mode ultrasonography. Significant ICA stenosis, > 70% ICA stenosis but less than near occlusion of the ICA, was diagnosed when the ICA/CCA peak systolic velocity ratio was ≥ 3.5.

RESULTS

Ninety-five patients, with a mean age of 58.52 ± 11.04 years, were studied. Twenty-five patients had a history of smoking, six patients had a history of coronary artery disease, six patients had hypertension, and ten patients had diabetes mellitus. Significant ICA stenosis was present in four patients (4.2%) with peripheral arterial disease in one healthy individual (1%) of the control group (P > 0.05). In terms of the risk factors for atherosclerosis, no statistically significant relationship was found between individual atherosclerotic risk factors and significant ICA stenosis (P > 0.05).

CONCLUSION

The prevalence of significant ICA stenosis in Iranian patients with peripheral arterial disease is low. In addition, there is no relationship between individual atherosclerotic risk factors and significant ICA stenosis.

Atherosclerotic renal artery stenosis--diagnosis and treatment

Renal artery stenosis (RAS) is characterized by a heterogeneous group of pathophysiologic entities, of which fibromuscular dysplasia and atherosclerotic RAS (ARAS) are the most common. Whether and which patients should undergo revascularization for ARAS is controversial. The general consensus is that all patients with ARAS should receive intensive medical treatment. The latest randomized clinical trials have increased confusion regarding recommendations for revascularization for ARAS. Although revascularization is not indicated in all patients with ARAS, experts agree that it should be considered in some patients, especially those with unstable angina, unexplained pulmonary edema, and hemodynamically significant ARAS with either worsening renal function or with difficult to control hypertension. A search of the literature was performed using PubMed and entering the search terms renal artery stenosis, atherosclerotic renal artery stenosis, and renal artery stenosis AND hypertension to retrieve the most recent publications on diagnosis and treatment of ARAS. In this review, we analyze the pathways related to hypertension in ARAS, the optimal invasive and noninvasive modalities for evaluating the renal arteries, and the available therapies for ARAS and assess future tools and algorithms that may prove useful in evaluating patients for renal revascularization therapy.

Endovascular intervention for renal artery stenosis

Renovascular diseases are common conditions with important implications on cardiovascular morbidity and mortality. Renal artery stenosis (RAS) is present in 1-5% of patients with hypertension (HTN) in the US with the vast majority of caused by atherosclerosis. Atherosclerotic RAS is related not only to uncontrolled HTN, but also to renal dysfunction. Atherosclerotic RAS in the USA has been reported to account for approximately 14-16% of new patients requiring dialysis each year. Hence a concerted effort was made in the last decade to treat renovascular stenosis using newly developed endovascular therapies to improve cardiovascular morbidity and renal function. A review on new advances in the endovascular management of renal artery stenosis with low profile stents, embolic protection devices, and drug eluting stents is presented.

Prevalence of renal artery stenosis in flash pulmonary oedema: determination using gadolinium-enhanced MRA

PURPOSE

The primary purpose was to determine the prevalence of renal artery stenosis (RAS) in patients presenting with acute ("flash") pulmonary oedema (FPE), without identifiable cause using contrast-enhanced magnetic resonance angiography (CE-MRA) of renal arteries. A secondary goal was to correlate clinical parameters at presentation with the presence or absence of RAS.

MATERIALS AND METHODS

Patients presenting with acute pulmonary oedema without identifiable cause prospectively underwent CE-MRA. >50% renal artery stenosis was considered significant. Clinical parameters (blood pressure, serum creatinine, history of hypertension/hyperlipidaemia) were compared in patients with and without RAS using an unpaired t-test. Results expressed; mean (+/-SD).

RESULTS

20 patients (4 male, 16 female, age 78.5+/-11 years) underwent CE-MRA. 9 patients (45%) had significant RAS (6 (30%) bilateral, 3 (15%) unilateral). Systolic BP was higher in patients with RAS (192+/-38 mm Hg) than those without (134+/-30 mm Hg) (p<.005). Diastolic BP was higher in patients with RAS (102+/-23 mm Hg) than those without (76+/-17 mm Hg) (p<.01). All patients with RAS and 6/11(55%) patients without RAS had a history of hypertension. No significant difference in creatinine or hyperlipidaemia history was observed.

CONCLUSION

The prevalence of RAS in patients presenting with FPE is 45%. The diagnosis should be considered in patients presenting with unexplained acute pulmonary oedema, particularly if hypertensive at presentation.

One year clinical outcomes of renal artery stenting: the results of ODORI Registry

The safety, efficacy and long term clinical benefits of renal artery revascularization by stenting are still a matter of debate. The aim of our study was to define the safety and efficacy of renal artery stenting with the Tsunami peripheral stent (Terumo Corporation, Tokyo, Japan). The ODORI was a prospective, multicentre registry which enrolled 251 consecutive patients, (276 renal arteries) in 36 centres across Europe. The primary endpoint was acute procedural success defined as <30% residual stenosis after stent placement. Secondary endpoints included major adverse events, blood pressure control, serum creatinine level, and target lesion revascularization (TLR) at 6 and 12 months. Patients were 70 +/- 10 years old, 59% were male, 33% had diabetes, and 96% hypertension. The main indications for renal stent implantation were hypertension in 83% and renal salvage in 39%. Direct stent implantation was performed in 76% of the cases. Acute success rate was 100% with residual stenosis of 2.5 +/- 5.4%. Systolic/diastolic blood pressure decreased from a mean of 171/89 at baseline to 142/78 mmHg at 6 months (p < 0.0001 vs. baseline), and 141/80 mmHg at 12 months (p < 0.0001 vs. baseline). Mean serum creatinine concentration did not change significantly in the total population. However, there was significant improvement in the highest tercile (from 283 micromol/l at baseline to 205 and 209 micromol/l at 6 and 12 months respectively). At 12-months, rates of restenosis and TLR were 6.6 and 0.8% respectively. The 12 month cumulative rate of all major clinical adverse events was 6.4% while the rate of device or procedure related events was 2.4%. In hypertensive patients with atherosclerotic renal artery stenosis Tsunami peripheral balloon-expandable stent provides a safe revascularization strategy, with a potential beneficial impact on hypertension control and renal function in the highest risk patients.

Cardiovascular morbidity and mortality and renal artery stenosis

Renal artery stenosis (RAS) is a common manifestation of atherosclerosis and is associated with many other atherosclerotic conditions. Cardiovascular morbidity and mortality is increased among patients with RAS. This increase is likely due in part to the associated disease states; however, RAS itself may also contribute. Current strategies to limit cardiovascular morbidity and mortality in RAS include various pharmacologic interventions targeting both RAS atherosclerosis in general. Additionally, revascularization has been advocated; however, clear data are lacking. Ongoing clinical trials such as the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial will ultimately help to determine the best strategies to limit the morbidity and mortality associated with RAS.

Epidemiology and natural history of atherosclerotic renovascular disease

Atheromatous renovascular disease (ARVD) is increasingly suspected and diagnosed, and it commonly presents to several different clinical specialties. In this review, the epidemiology, risk factors, comorbid disease associations, natural history, and prognosis of ARVD is described. Atheromatous renovascular disease is strongly associated with macrovascular pathology in other important vascular beds, especially the coronary, aortoiliac and iliofemoral circulations, and also with structural and functional heart disease. These clinicopathologic relationships contribute to the high morbidity and mortality associated with the condition. Understanding of the natural history of renal artery stenosis may enable intensified treatment strategies to reduce associated risk and improve patient prognosis.

The prevalence of atherosclerotic renal artery stenosis in risk groups: a systematic literature review

OBJECTIVE

We performed a literature review and analysis to improve the insight in the prevalence of renal artery stenosis (RAS) in risk groups.

METHODS

Relevant studies were identified by a MEDLINE and EMBASE database search (1966 to December 2007), complemented by hand searching of reference lists. Review was restricted to English language studies, using any form of angiography as diagnostic method. Studies were grouped in risk group categories sharing similar clinical characteristics, and pooled prevalence rates were calculated for each category.

RESULTS

Forty studies, involving a total number of 15 879 patients, were identified. The following pooled prevalence rates (95% confidence interval; sample size risk group) of RAS were found: suspected renovascular hypertension, 14.1% (12.7-15.8%; n = 1931); hypertension and diabetes mellitus, 20% (14.9-25.1%; n = 240); coronary angiography (CAG) in consecutive patients, 10.5% (9.8-11.2%; n = 8011); CAG in hypertensive patients, 17.8% (15.4-20.6%; n = 836); CAG and suspected renovascular disease, 16.6% (14.8-18.5%; n = 1576); congestive heart failure, 54.1% (45.7-62.3%; n = 135); peripheral vascular disease, 25.3% (23.6-27.0%; n = 2632); abdominal aortic aneurysm, 33.1% (27.4-39.2%; n = 239) and end-stage renal failure, 40.8% (27-55.8%; n = 49.) In patients with an incidentally discovered RAS, hypertension and renal failure were present in 65.5 and 27.5%, respectively.

CONCLUSION

RAS has a high prevalence in risk groups, especially in those with extrarenal atherosclerosis, end-stage renal failure and heart failure. These findings are important when screening for RAS or prescription of an angiotensin converting enzyme inhibitor or angiotensin-II receptor blocker is considered.

The role of percutaneous revascularization for renal artery stenosis

Renal artery stenosis (RAS) is usually caused by atherosclerosis or fibromuscular dysplasia. RAS leads to activation of the renin-angiotensin-aldosterone system and may result in hypertension, ischemic nephropathy, left ventricular hypertrophy and congestive heart failure. Management options include medical therapy and revascularization procedures. Recent studies have shown angiotensin receptor blockers (ARB) and angiotensin converting enzyme inhibitors (ACE-I) to be highly effective in treating the hypertension associated with RAS and in reducing cardiovascular events; however, they do not correct the underlying RAS and loss of renal mass may continue. Renal artery angioplasty was first performed by Gruntzig in 1978. The routine use of stents has increased technical success rates compared with angioplasty, and surgery is now only rarely performed. Although numerous case series claimed benefit in terms of blood pressure control, no adequately powered randomized, controlled, prospective study of renal artery interventions has reported their effect on cardiovascular morbidity or mortality. The CORAL trial, an ongoing study of renal artery stent placement and optimal medical therapy (OMT) funded by the National Institutes of Health, is the first study to attempt to do so. Until the CORAL trial results are in, physicians will continue to be faced with difficult choices when determining the optimal management for RAS patients and deciding which, if any, patients should be offered revascularization.

Guidelines for Screening of Extracranial Carotid Artery Disease: A Statement for Healthcare Professionals from the Multidisciplinary Practice Guidelines Committee of the American Society of Neuroimaging; Cosponsored by the Society of Vascular and Interventional Neurology

The aim of this new statement is to provide comprehensive and timely evidence-based recommendations on the screening for asymptomatic carotid artery stenosis in the general population and selected subsets of patients. Recommendations are included for high-risk persons in the general population; patients undergoing open heart surgery including coronary artery bypass surgery; patients with peripheral vascular diseases, abdominal aortic aneurysms, and renal artery stenosis; patients after radiotherapy for head and neck malignancies; patients following carotid endarterectomy, or carotid artery stent placement; patients with retinal ischemic syndromes; patients with syncope, dizziness, vertigo or tinnitus; and patients with a family history of vascular diseases and hyperhomocysteinemia. The recommendations are based on prevalence of disease, anticipated benefit, and concurrent guidelines from other professional organizations in selected populations.

Stent revascularization for the prevention of cardiovascular and renal events among patients with renal artery stenosis and systolic hypertension: rationale and design of the CORAL trial

BACKGROUND

Atherosclerotic renal artery stenosis is a problem with no consensus on diagnosis or therapy. The consequences of renal ischemia are neuroendocrine activation, hypertension, and renal insufficiency that can potentially result in acceleration of atherosclerosis, further renal dysfunction, myocardial infarction, heart failure, stroke, and death. Whether revascularization improves clinical outcomes when compared with optimum medical therapy is unknown.

METHODS

CORAL is a randomized clinical trial contrasting optimum medical therapy alone to stenting with optimum medical therapy on a composite cardiovascular and renal end point: cardiovascular or renal death, myocardial infarction, hospitalization for congestive heart failure, stroke, doubling of serum creatinine, and need for renal replacement therapy. The secondary end points evaluate the effectiveness of revascularization in important subgroups of patients and with respect to all-cause mortality, kidney function, renal artery patency, microvascular renal function, and blood pressure control. We will also correlate stenosis severity with longitudinal renal function and determine the value of stenting from the perspectives of quality of life and cost-effectiveness. The primary entry criteria are (1) an atherosclerotic renal stenosis of > or = 60% with a 20 mm Hg systolic pressure gradient or > or = 80% with no gradient necessary and (2) systolic hypertension of > or = 155 mm Hg on > or = 2 antihypertensive medications. Randomization will occur in 1080 subjects. The study has 90% power to detect a 28% reduction in primary end point hazard rate.

CONCLUSIONS

CORAL represents a unique opportunity to determine the incremental value of stent revascularization, in addition to optimal medical therapy, for the treatment of atherosclerotic renal artery stenosis.

Increase in Utilization of Percutaneous Renal Artery Interventions by Medicare Beneficiaries, 1996–2000

OBJECTIVE

Our purpose was to review data from Medicare physician claims to ascertain differences in annual volumes of renal artery interventions versus surgery and differences in utilization of renal artery interventions among geographic regions according to physician provider type between 1996 and 2000.

MATERIALS AND METHODS

We analyzed claims submitted to Medicare in 1996, 1998, and 2000 and extracted claims for renal artery angioplasty, stent placement, or bypass surgery. Analyses were performed for percutaneous renal artery interventions categorized by Centers for Medicare & Medicaid Services (CMS) geographic region and physician provider type.

RESULTS

Between 1996 and 2000, the total volume of renal revascularization (surgical and percutaneous) increased 62%, from 13,380 to 21,660 procedures. The annual volume of renal artery surgery decreased 45% in 2000, compared with the volume in 1996. Annual volumes of renal artery angioplasty and stent placement increased 2.4-fold in 2000 compared with those in 1996. Most growth in percutaneous renal artery interventions is attributed to added provision by cardiologists, who increased their annual volume 3.9-fold. More than a threefold difference in rates of use of renal artery interventional procedures across CMS regions was found. In the Southeast region, the volume of renal artery interventions by cardiologists increased more than 15-fold.

CONCLUSION

Among Medicare beneficiaries, the volume of percutaneous renal artery interventions is increasing rapidly, whereas the volume of renal artery surgery is declining. Most growth in percutaneous renal artery revascularization is attributed to increased performance by cardiologists; explosive growth in annual procedure volume by cardiologists occurred in some regions. Marked disparity in use among CMS regions was found.

Renal insufficiency as a predictor of adverse events and mortality after renal artery stent placement

BACKGROUND

Renal artery stenosis (RAS) is associated with substantial morbidity and mortality. This relationship is strongest in the presence of renal insufficiency (RI). The goal of this study is to assess the relationship between RI, mortality, and adverse events in the setting of renovascular disease.

METHODS

Two hundred sixty-one patients with significant RAS treated with endovascular stenting were followed up prospectively for 21 +/- 18 months (range, 0 to 85 months). Blood pressure (BP), renal function, medication use, and comorbidities were assessed. Death was verified through the Social Security Death Master Index File, and cause of death was derived from death certificates. Medical records of 230 subjects subsequently were reviewed to identify adverse cardiovascular and renal events.

RESULTS

Overall, 37% of patients experienced at least 1 adverse event postprocedure. Myocardial infarction (MI) and congestive heart failure (CHF) events increased with degree of baseline RI. Seventy-three deaths (28%) occurred postprocedure (range, 13 to 2,457 days). Baseline characteristics associated with mortality included advanced age, decreased use of beta-blockers, increased use of diuretics, increased serum creatinine (Cr) level, decreased Cr clearance (CrCl), bilateral stenoses or stenosis of a solitary kidney, history of CHF, and history of MI. Follow-up characteristics associated with mortality included lower systolic and diastolic BP, increased serum Cr level, and decreased CrCl. RI at baseline and follow-up remained associated with mortality after adjusting for other clinically and statistically significant variables. Patients in whom renal function improved after stenting appeared to show improved survival over those without improved renal function (45% versus 0% cumulative survival, P < 0.05).

CONCLUSION

In patients with RAS undergoing stent therapy, baseline RI is associated with an increased incidence of adverse events, as well as decreased survival, independent of other baseline clinical factors. Importantly, improvement in renal function appears to be associated with increased survival.

Preoperative construction of an extracranial arterial shunt for resection of an aortic arch aneurysm with occluded left carotid artery

A 68-year-old man with aortic arch aneurysm was referred to our department. Preoperative carotid echography and magnetic resonance angiography revealed occlusion of the left internal carotid artery. Single-photon emission computed tomography scanning indicated that cerebral blood flow was decreased and reactivity to acetazolamide was reduced in the left temporal lobe. A successful superficial temporal artery-middle cerebral artery anastomosis was first made by neurosurgeons. A postoperative single-photon emission computed tomography scan showed that cerebral blood flow and reactivity to acetazolamide were remarkably improved. Two months after the anastomosis, the aortic arch aneurysm was successfully repaired.

Chronic renal ischemia: implications for cardiovascular disease risk

Chronic renal ischemia caused by atherosclerotic renal artery stenosis (RAS) is gaining recognition as a potentially important risk factor for cardiovascular (CV) morbidity and mortality. The etiology of increased risk of CV events is multifaceted and includes direct physiologic changes that increase risk as well as intermediate clinical effects that are associated with worse outcome. Physiologic changes associated with increased CV risk in patients with RAS include increased production of fibrogenic and vasoactive peptides such as renin, angiotensin, endothelin, and catecholamines, as well as endothelial cell dysfunction. Clinical intermediate conditions associated with higher incidences of CV events seen in patients with renal ischemia include hypertension, systemic atherosclerosis, chronic renal failure, and left ventricular hypertrophy and dysfunction. More thorough understanding of the myriad physiologic changes seen in patients with RAS will likely improve patient selection for renal artery revascularization. Clinical trials should examine a full range of CV and renal outcomes, not just blood pressure, to adequately assess the merits of revascularization.

Total serum homocysteine--a predictor of extracranial carotid artery stenosis in male patients with symptomatic peripheral arterial disease

High total serum homocysteine (tHcy) concentrations are associated with an increased risk of carotid artery disease in the general population. Since patients with peripheral arterial disease (PAD) have a threefold risk of cerebrovascular morbidity compared to individuals free of PAD, and since the total neurological event rate is associated with a > or = 50% lumen reduction in extracranial carotid arteries, it was tested whether tHcy is a predictor of internal carotid artery stenosis in patients with symptomatic PAD. A total of 443 consecutive male PAD patients without previous carotid surgery/stenting were studied. In all, 100 patients with PAD had an internal carotid artery stenosis > or = 50%. Of the remaining 343 patients, 100 individuals matched for age (+/- 2 years) and diabetes served as controls. The extent of carotid stenosis was evaluated with color duplex measurement; tHcy was determined by high-performance liquid chromatography. Cases displayed a significantly higher median fasting tHcy level (17.0 micromol/l) than controls (13.7 micromol/l, p=0.001). Multivariate analysis showed that tHcy (p=0.036) was an independent predictor of internal carotid artery stenosis > or = 50% in PAD patients, representing an odds ratio of 1.32 (95% CI, 1.02-1.72) for an increment of 5 micromol/l. In the present study, high tHcy was an independent risk factor for an internal carotid artery stenosis > or = 50% in patients with PAD. Since PAD patients suffer a threefold risk of stroke compared to healthy individuals, a simple vitamin substitution in PAD patients may reduce the occurrence of internal carotid artery stenosis and therefore diminish the relatively high rate of cerebrovascular events in this population.

Cost of routine screening for carotid and lower extremity occlusive disease in patients with abdominal aortic aneurysms

OBJECTIVE

The burden of clinically relevant noncoronary atherosclerotic occlusive disease in patients with abdominal aortic aneurysms (AAAs) is poorly defined. Furthermore, the cost-effectiveness of routine versus selective preoperative noninvasive examination of the carotid and lower extremity arterial beds has not been established in patients who undergo elective AAA repair.

METHODS

Diagnostic vascular laboratory study results were reviewed in 206 patients who underwent evaluation before AAA repair from 1994 to 1998. The patients underwent routine preoperative carotid duplex scan examinations and lower extremity Doppler scan arterial studies with ankle-brachial index (ABI) determinations. The medical records were reviewed for the identification of clinical evidence consistent with cerebrovascular or lower extremity arterial occlusive disease. The costs of routine screening and selective screening were determined with Medicare reimbursement schedules.

RESULTS

The prevalence rate of advanced (80% to 100%) carotid artery stenosis (CAS) was 3.4%, and 18% of the patients had CAS between 60% and 100%. Advanced peripheral vascular occlusive disease (PVOD; ABI, <0.3) was found in 3% of the patients, and 12% of the patients had an ABI of less than 0.6. Most patients with advanced CAS (71%) or advanced PVOD (83%) had clinical indications of their disease. The absence of clinical evidence of disease had a negative predictive value of 99% for both advanced CAS and PVOD. The cost of routine screening for all patients for advanced CAS was $5445 per case. Routine screening for severe PVOD costs were $3732 per case discovered. In contrast, the costs for selective screening for advanced CAS or PVOD in patients with appropriate history or symptoms were $1258 and $785 per case found, respectively.

CONCLUSION

Routine noninvasive diagnostic testing for the identification of asymptomatic CAS and PVOD in patients with AAA may not be justified. Preoperative screening is more clearly indicated for patients with AAAs who have clinical evidence suggestive of CAS or PVOD.

Treatment options for renovascular hypertension

Renovascular hypertension is usually caused by atherosclerotic narrowing of the origin of the renal artery and is much more common than is thought among patients with peripheral vascular disease, carotid stenosis or heart failure. Renovascular hypertension must be distinguished from renal artery stenosis. In true renovascular hypertension, the kidney takes charge of the blood pressure and will do what it takes to push blood pressure high enough to force blood through the blocked artery. This can be diagnosed with functional tests that measure glomerular filtration rate before and after blockade of the renin-angiotensin system with angiotensin converting enzyme inhibitors or antagonists of the AT(1) subtype of the angiotensin receptor. There is insufficient data on which to make evidence-based recommendations on the management of renovascular hypertension. Only two randomised trials exist of angioplasty versus medical therapy and of these the larger was severely contaminated by angioplasty among the group initially assigned to medical therapy. Only one trial exists of angiotensin converting enzyme inhibition versus alternative medical therapy. The drugs that are most effective in medical management of renovascular hypertension--angiotensin converting enzyme inhibitors and angiotensin receptor-1 blockers--tend to be avoided because of fear of a very rare complication (acute renal failure in patients with severe stenosis of both renal arteries, or the artery to a single remaining kidney). This fear is misplaced not only because it is rare (< 5% of patients with renovascular hypertension) but because it is reversible and treatable by revascularisation. Patients with renovascular hypertension should be evaluated by nuclear medicine differential glomerular filtration rate, enhanced by blockers of the renin-angiotensin system. If medical therapy is ineffective or causes severe impairment of renal function, revascularisation is required. Some experts favour surgical revascularisation because of occasional angioplasty failure and the risk of deterioration of renal function after angioplasty.

Combined infrarenal aorta and carotid artery reconstruction: early and late outcome in 152 patients

Between January 1, 1985 and December 31, 1998, we performed combined infrarenal aorta and carotid artery reconstruction in 152 consecutive patients. The mean age of these patients was 65.4 +/- 8.6 years (range, 43-88 years). Infrarenal aortic disease involved abdominal aortic aneurysm in 78 patients (44.7%) and occlusive aortoiliac lesions in 84 (55.3%). Carotid artery disease was detected by performing routine Doppler ultrasonography prior to aortic reconstruction. A total of 121 carotid lesions were asymptomatic (79.6%). A total of 32 patients (21%) had a history of contralateral carotid repair. Eighty-one patients (53.2%) presented with coronary artery disease diagnosed on the basis of clinical and/or laboratory testing. Concurrent lesions were diagnosed in the renal arteries of 43 patients (28.3%) and in the visceral arteries of 16 (10.5%). Based on the results of cardiac evaluation, eight patients underwent coronary revascularization before combined reconstruction. Renal or visceral artery reconstruction was carried out during the same procedure in 30 (19.7%) and 10 (6.6%) patients, respectively. Univariate analysis demonstrated six factors that were significantly associated with perioperative mortality and morbidity: age, coronary artery disease, chronic obstructive pulmonary disease, procedure time, intraoperative blood loss, and creatinemia over 140 micromol/L. Multivariate analysis showed that only the first four of these factors were independent. Actuarial survival in the overall population, including the patients who died during the perioperative period, was 73.9 +/- 7.1% at 5 years and 50.9 +/- 10% at 10 years. From our experience, we conclude that combined infrarenal aorta and carotid artery reconstruction can be performed with no additional operative risks and consequently is the strategy of choice. In our series neither procedure had any effect on the early or late outcome of the other. Our experience suggests that combined surgery is a safe alternative to staged surgery in patients with concurrent lesions involving the infrarenal aorta and carotid artery bifurcation.

Renal artery revascularization in combination with infrarenal aortic reconstruction

Associated stenosis of one or both renal arteries is not uncommon in patients with infrarenal aortic disease (aneurysm or occlusive disease) requiring surgical repair. The purpose of this retrospective study was to analyze the short- and long-term outcome of concomitant renal artery and aortic reconstruction. The present series includes 39 consecutive concomitant procedures. Simultaneous aortic and renal artery reconstruction was performed in a total of 39 (7.2%) of the 540 patients who underwent elective infrarenal abdominal aortic repair between 1987 and 1996. There were 33 men and 6 women with a mean age of 66.7 years. Twenty-eight patients presented hypertension and 7 presented renal insufficiency associated with hypertension. In all cases, the indication for operative treatment was aortic disease, i.e., aortic aneurysm in 20 cases and occlusive aortoiliac disease in 19 cases. A total of 51 renal artery revascularization procedures were performed, including bypass in 40 cases, transposition in 7, and endarterectomy in 4. Combined aortic and renal artery reconstruction gives good short- and long-term results comparable to those of isolated aortic surgery. On the basis of these findings, we think that concomitant repair is the strategy of choice for patients presenting renal artery stenosis associated with infrarenal aortic disease requiring surgical therapy.

Management of resistant hypertension in patients with carotid stenosis: high prevalence of renovascular hypertension

INTRODUCTION

Patients with carotid stenosis are at high risk of vascular events and therefore require an optimal control of risk factors such as hypertension. As the treatment of hypertension differs according to the cause, we examined the prevalence of resistant hypertension, and the cause of hypertension, among patients with carotid stenosis followed closely in two randomized trials of carotid endarterectomy.

OBJECTIVE

The purpose of this study was to determine the prevalence of resistant hypertension and of secondary hypertension among patients with carotid stenosis.

METHODS

A chart review was performed of all patients from our center who participated in the North American Symptomatic Carotid Endarterectomy Trial or the Asymptomatic Carotid Artery Study to determine the prevalence of renovascular hypertension.

RESULTS

Among 170 patients with carotid stenosis followed in these two trials, 145 (83.5%) were hypertensive (systolic >160 or diastolic >90 mm Hg); at least 24 (14.1% overall, 16.6% of hypertensives) had renovascular hypertension based on either nuclear medicine renography, renal angiography or both; among the 79 patients with resistant hypertension (mean arterial pressure >130 mm Hg despite treatment), 20 (25.3%) had renovascular hypertension. Adrenocortical hyperplasia was the underlying cause of hypertension in 12 (7.1% of cases, 8.3% of hypertensives, 8.8% of resistant hypertensives). Blood pressures were significantly higher for patients with renovascular and adrenocortical hypertension (p < 0.0001 for systolic, p = 0.024 for diastolic pressures).

CONCLUSION

Among patients with carotid stenosis, renovascular hypertension is unusually common. Resistant hypertension among such patients should lead to investigation and management directed at the cause of hypertension. Appropriate investigations might include plasma renin/aldosterone ratio, captopril renography and MRA of the renal arteries or renal angiography.

Prevalence of renal artery stenosis in autopsy patients with stroke

BACKGROUND AND PURPOSE

Atherosclerotic renal artery stenosis commonly exists as one manifestation of more generalized atherosclerosis. It is a progressive but potentially curable disorder. Thus, information on renal artery involvement in atherosclerotic diseases could be important. We investigated the prevalence of renal artery stenosis in autopsied patients with stroke over 40 years of age.

METHODS

From 2167 consecutive autopsy patients who died between 1980 and 1997, we studied 346 cases of mean age of 69+/-11 years with clinical evidence of stroke.

RESULTS

Atherosclerotic renal artery stenosis (>/=75% luminal area narrowing) was found in 36 patients (10.4%). Patients with renal artery stenosis were older and had worse renal function. Renal artery stenosis was found in 14.7%, 28.6%, and 23.9% of patients with hypertension, renal insufficiency, and aortic aneurysm, respectively. Extracranial carotid artery stenosis (>50% luminal area narrowing) was found in 101 patients (29.2%). Of the 346 stroke patients, 256 had a history of brain infarction. In patients with brain infarction, renal artery stenosis was found in 31 (12.1%) and carotid stenosis was found in 81 (33.6%). Patients with carotid artery stenosis were more likely to have renal artery stenosis than patients without carotid artery stenosis (24.4% versus 5.9%, P<0.0001). Multiple logistic regression analysis identified renal insufficiency, hypertension, female gender, and presence of carotid artery stenosis as independent predictors of renal artery stenosis in patients with brain infarction.

CONCLUSIONS

These data reveal that atherosclerotic renal artery stenosis is common in patients with stroke, especially in those with brain infarction.

Use of limited color-flow duplex for a carotid screening project

BACKGROUND

Although the efficacy of carotid endarterectomy for asymptomatic carotid stenosis has been established, no cost-effective approach for identification of these patients has yet been devised. The purpose of this study was to develop a limited carotid duplex screening examination to be utilized for the detection of asymptomatic carotid stenoses.

METHODS

Carotid screening examinations employed rapid identification of the carotid bifurcation using color-flow duplex imaging and an immediate Doppler-derived velocity of the segment of the internal carotid artery with the most turbulent flow. Complete examinations were then finished using well-established protocols in our accredited vascular laboratory. A total of 512 patients were referred for complete studies based upon standard indications. Criteria for at least a 50% internal carotid artery stenosis on the complete examination was defined as a peak systolic velocity (PSV) of at least 125 cm/sec. Receiver operator characteristic (ROC) curves were then constructed to identify the optimal screening velocity criteria as compared with the final results on the complete examination.

RESULTS

Five screening examinations were technically limited yielding a total of 507 patients with 1,014 carotid arteries available for analysis. Comparison of screening examinations versus complete examinations for a PSV of 125 cm/sec yielded sensitivity 86%, specificity 98%, positive predictive value (PPV) 95%, and a negative predictive value (NPV) 93%. ROC analysis identified a "cut point" of 115 cm/sec on the screening examinations to achieve sensitivity 91%, specificity 95%, PPV 89%, and NPV 96%. Time to perform screening examinations averaged 3.2 minutes per patient. Three patients had common carotid lesions not identified on the limited internal carotid screening examinations.

CONCLUSIONS

Screening carotid examinations are a rapid, reliable, and relatively inexpensive method for detection of patients with asymptomatic internal carotid artery stenosis. Limited screening examinations should be developed in each vascular laboratory and utilized in high-risk patients.