Revascularisation of renal artery stenosis caused by fibromuscular dysplasia: effects on blood pressure during 7-year follow-up are influenced by duration of hypertension and branch artery stenosis

Contemporary outcomes for branch renal artery repair

BACKGROUND

The purpose of this study was to provide an updated description of demographics, technical details, and clinical outcomes of 101 consecutive branch renal artery repairs in 98 patients using cold perfusion.

METHODS

A single-institution, retrospective analysis branch renal artery reconstructions was performed between 1987 and 2019.

RESULTS

Patients were predominantly Caucasian (80.6%) women (74.5%) with a mean age of 46.8 ± 15.3 years. The mean preoperative systolic and diastolic blood pressures were 170.4 ± 33.0 mm Hg and 99.2 ± 19.9 mm Hg, respectively, requiring a mean of 1.6 ± 1.1 antihypertensive medications. The estimated glomerular filtration rate was 84.0 ± 25.3 mL/min. Most patients (90.2%) were not diabetic and never smokers (68%). Treated pathology included aneurysm (87.4%) and stenosis (23.3%) with histology demonstrating fibromuscular dysplasia (44.4%), dissection (5.1%), and degenerative not otherwise specified (50.5%). The right renal arteries were most frequently treated (44.2%), with a mean of 3.1 ± 1.5 branches involved. Reconstruction was accomplished using bypass in 90.3% of cases using aortic inflow in 92.7% and a saphenous vein conduit in 92%. Branch vessels served as outflow in 96.9% and syndactylization of branches was used to decrease the number of distal anastomoses in 45.3% of repairs. The mean number of distal anastomoses was 1.5 ± 0.9. Postoperatively, the mean systolic blood pressure improved to 137.9 ± 20.8 mm Hg (mean decrease of 30.5 ± 32.8 mm Hg; P < .0001) and the mean diastolic blood pressure improved to 78.4 ± 12.7 mm Hg (mean decrease of 20.1 ± 20.7 mm Hg; P < .0001) with patients requiring a mean of 1.4 ± 1.0 antihypertensive medications (mean decrease of 0.2 ±1.0 medications; P = .048). The postoperative estimated glomerular filtration rate was 89.1 mL/min (mean increase of 4.1 mL/min; P = .08). The mean length of stay was 9.0 ± 5.8 days and 96.1% of patients were discharged home. The mortality rate was 1% (one patient with liver failure) and the major morbidity rate was 15%. There were five infectious complications (pneumonia, Clostridium difficile, and wound infection) and five patients required return to the operating room (one for nephrectomy, one for bleeding, two for thrombosis, and one for second trimester pregnancy loss requiring dilation and curettage and splenectomy). One patient required temporary dialysis owing to graft thrombosis. Two patients developed arrhythmias. No patients suffered a myocardial infarction, stroke, or limb loss. After 30 days, follow-up data were available for 82 bypasses. At this time, three reconstructions were no longer patent. Intervention was required to retain patency for five bypasses. After 1 year, patency data were available for 61 bypasses and five were no longer patent. Of the five grafts with loss of patency, two underwent intervention in attempt to maintain patency, which subsequently failed.

CONCLUSIONS

Repair of renal artery pathology involving the branches can be performed with short- and long-term technical success and significant prospect of decreasing an elevated blood pressure. The operations required to fully address the presenting pathology are often quite complex involving multiple distal anastomoses and consolidation of small secondary branches. The procedure carries a small but significant risk of major morbidity and mortality.

Prevalence and clinical characteristics of renovascular hypertension associated with fibromuscular dysplasia in China

OBJECTIVES

The aim of this study was to investigate the clinical characteristics of renal artery fibromuscular dysplasia (FMD) in patients in China and identify the cure rate of hypertension after angioplasty.

METHODS

Consecutive hypertensive patients with renal artery stenosis caused by FMD who underwent catheter-based angiography, and were followed at two Chinese referral centres, were retrospectively analysed. All patients underwent a detailed investigation, including demographic characteristics, clinical characteristics, biochemical sampling, Doppler ultrasonography of carotid arteries, magnetic resonance angiography (MRA) of the intracranial artery, and CTA or MRA of the abdominal artery and catheter-based renal angiography. Patients were routinely followed up at 1 month, 6 months and every year after the procedure.

RESULTS

Among 245 study participants, with a mean diagnosed age of 26.9 ± 9.9 years, 137 (55.9%) were women, and 38 (15.5%) were children. All patients were diagnosed with hypertension at a mean age of 23.4 ± 8.4 years. There were 73.5% focal and 15.2% multivessel cases. Aneurysms, arterial dissections and total occlusions were found in 21.6, 4.1 and 12.2% of patients, respectively. Patients with multifocal FMD were older (26.0 vs. 23.7 years, P  = 0.021) and more often female (70.8 vs. 50.6%, P  = 0.004). Among children with renal FMD, 55.2% were men, and 86.8% were focal. After a median follow-up of 7.0 years, multifocal FMD had a higher cure rate of hypertension than focal FMD after revascularization (71.7 vs. 55.8%, P  = 0.032).

CONCLUSION

In a cohort of mostly young Chinese patients, the prevalence of hypertension associated with renal FMD is similar in both sexes. Focal FMDs were more frequent than the multifocal ones and, after angioplasty, were associated with a worse blood pressure outcome.

Blood pressure and renal outcomes after renal artery aneurysm intervention: Single-center experience and review of literature

Objective

To explore the results of hypertension improvement and renal function preservation after renal artery aneurysm (RAA) repair.

Methods

This study retrospectively analyzed the change in blood pressure (BP) and renal outcomes of 59 RAA patients throughout either open or endovascular operations and follow-up at a large center. Patients were grouped according to the difference in their BP at the last follow-up vs. their baseline value. Logistic regression was conducted to explore risk factors for perioperative BP relief and long-term hypertension reonset. Previous studies of RAA with records of BP, blood creatinine level, or GFR/eGFR results are reviewed.

Results

Hypertension was observed in 62.7% (37/59) of the patients included. Postoperative BP declined from 132.20 ± 16.46/79.92 ± 9.64 mmHg to 122.41 ± 11.17/71.10 ± 9.82 mmHg, while eGFR changed from 108.17 ± 24.73 to 98.92 ± 23.87 ml/min/1.73 m². The median follow-up was 854 [IQR: 1,405] days. Both open and endovascular techniques significantly relieved hypertension and did not impair renal function much. Lower preoperative systolic BP (SBP) was significantly associated with hypertension relief (OR = 0.83, 95% CI: 0.70-0.99). Among patients with normal BP after the operation, higher postoperative SBP was significantly associated with new-onset hypertension (OR = 1.14, 95% CI: 1.01-1.29). Literature review indicated that renal function usually remained normal at follow-up, whereas relief of hypertension varied.

Conclusion

Patients with lower preoperative SBP were likely to benefit more from the operation, while higher postoperative SBP indicated a higher chance of hypertension reonset. Creatinine level and eGFR generally remained stable regardless of operation type.

Percutaneous Transluminal Renal Angioplasty for Fibromuscular Dysplasia and Prognostic Risk Factors: A Retrospective Chinese Cohort Study

Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory vascular disease involving small-to-medium-sized arteries. The characteristics of Chinese patients with FMD remain unclear. We retrospectively analyzed the data of patients with renal FMD who underwent percutaneous transluminal renal angioplasty (PTRA) for the first time at Fuwai Hospital between 2010 and 2021. The variables were selected through least absolute shrinkage and selection operator regression (LASSO), and logistic regression models were constructed to identify independent risk factors. A total of 116 patients (52 males, median age at diagnosis, 25.0 years) were enrolled. Elevated blood pressure was the leading complaint. After a median follow-up period of 18.0 months (interquartile range: 6.0-48.0 months), hypertension recurred in 34 patients and restenosis in nine patients, among whom four patients underwent secondary intervention and one patient underwent surgical revascularization. Bilateral renal artery involvement (odds ratio [OR]: 2.61, 95% confidence interval [CI]: 1.11-6.15; p = 0.028) and age at hypertension onset (OR: 0.93, 95% CI: 0.88-0.99; p = 0.018) were independent prognostic factors for adverse outcomes. The results indicate that patients with bilateral renal artery involvement and younger age at hypertension onset are more likely to have poorer clinical outcomes after PTRA, and should be more closely monitored.

Endovascular interventions in main renal artery pathologies: an overview and update

Renal arteries are involved in a wide spectrum of pathologies including atherosclerosis, fibromuscular dysplasia, Takayasu arteritis, aneurysms, and aortic type B dissections extending into main renal arteries. They manifest as renovascular hypertension, renal ischemia, and cardiovascular dysfunction. The location of the renal arteries in relation to the abdominal aortic aneurysm is a critical determinant of interventional options and long-term prognosis. This article provides a comprehensive review of the role of interventional radiologists in transcatheter interventions in various pathologies involving the main renal arteries with analysis of epidemiology, pathophysiology, newer interventional techniques, and management options.

Difficulty and importance of diagnosing stenosis of renal branch artery in fibromuscular dysplasia: a case report

A 16-year-old patient presented with abdominal pain and sustained hypertension. Thorough evaluation including renography with and without captopril and renal vein renin sampling were normal. Duplex ultrasound, however, raised suspicion of a renal artery stenosis. This was confirmed by computed tomography angiography which showed a severe branch artery stenosis with post-stenotic dilatation consistent with focal fibromuscular dysplasia (FMD). As the hypertension was resistant to 3 classes of antihypertensive treatment, percutaneous transluminal renal angioplasty (PTRA) was offered. The procedure had immediate effect on the blood pressure. Without medication the patient remains normotensive 4 years after and the abdominal pain has only sporadically returned. The presented case illustrates the challenging process of diagnosing FMD-related renal branch artery stenosis as well as the potential benefits of PTRA in this patient group.

Outcomes Following the Endovascular Treatment of Renal Artery Stenosis Caused by Fibromuscular Dysplasia: A Systematic Review and Meta-Analysis

OBJECTIVE

Renal artery revascularization has been performed to improve blood pressure control and to cure hypertension in patients with renal artery fibromuscular dysplasia (RAFMD). We herein conducted a systematic review and meta-analysis of studies assessing outcomes associated with the treatment of hypertensive RAFMD patients via endovascular angioplasty in order to offer an up-to-date overview of the relative costs and benefits of this approach to revascularization in RAFMD patients.

METHODS

We systematically searched the PubMed and Embase databases and the Cochrane Central Register for Controlled Trials to identify relevant studies published as of January 15, 2020. Key outcomes of interest in these studies included technical success, the incidence of perioperative complications, cure rates, and overall improvement rates.

RESULTS

In total, we identified 36 relevant studies of 1916 total repairs conducted in 1191 patients. Of these included studies, 33 were retrospective, while 3 were prospective. The overall technical success rate across these studies was 94.3%. Rates of total, major, and minor complications in these pooled studies were 12.9%, 4.6%, and 7.4%, respectively. Pooled rates of cured hypertension and improved hypertension following angioplasty, defined according to study-specific criteria, were 37.0% [95% CI: 27.0%-47.0%] and 80.0% [95% CI: 75.0% to 84.0%], respectively, although these rates varied highly among studies. Cure rates for studies used current clinical definitions for substantial variations across studies. Cure rates in studies using current definitions of cured hypertension (blood pressure <140/90 mm Hg without treatment) were just 18.1% following angioplasty. Cure rates fell markedly with increasing mean patient age (OR associated with an increase in mean age of 10 years: -0.24 [95% CI: -0.44 to -0.04, P = 0.019] and with mean known duration of hypertension (OR associated with an increase in mean hypertension duration of 5 years: -0.09 [95% CI: -0.12 to -0.05, P = 0.001]).

CONCLUSIONS

These findings suggest that endovascular treatment yielded moderate benefits to RAFMD patients, with substantial variation across studies. The blood pressure outcome was strongly influenced by patient age.

[Percutaneous angioplasty of renal artery stenosis: Short- and long-term results]

INTRODUCTION

Renal artery stenosis (RAS) may be symptomatic. The treatment of these lesions is primarily medical but may sometimes require surgical or endovascular revascularization. RAS angioplasty is well controlled but its results are discussed. The objective of this work was to report the short- and long-term results of the endovascular treatment of renal arteries in our center.

METHODS

We report a retrospective study between 2013 and 2018, including patients who received endovascular treatment for severe symptomatic RAS (≥75%).

RESULTS

Our population consisted of 17 patients. Mean age was 51.1 years [18-76], sex ratio 2.4. RAS was discovered during work-up for severe renovascular hypertension resistant to medical treatment for 16 patients and rapidly progressive renal failure for one patient. The etiology retained was: atherosclerosis (9 cases), fibromuscular dysplasia (6 cases) and Takayasu's disease (2 cases). The average stenosis rate was 85.9% [75-97%]. We performed simple angioplasty in 47% of the cases and stenting in 53%. The technical success rate was 100%. At 1 month, morbidity-mortality rates were zero. Mean follow-up was 12 months [6-36 months]. Patients with renovascular hypertension experienced a decrease in blood pressure, with discontinuation of antihypertensive therapy in 62.5% of cases and reduction of doses in 37.5% of cases. The permeability rate was 100% at 1 year, 94% at 2 years and 94% at 3 years. One patient had asymptomatic stent thrombosis at the 18th month. The restenosis rate was zero.

CONCLUSION

Angioplasty of symptomatic RAS may be indicated as first-line treatment. It is associated with satisfactory results in the short and long terms.

Factors Associated with Outcomes of Percutaneous Transluminal Renal Angioplasty in Patients with Renal Artery Stenosis: A Retrospective Analysis of 50 Consecutive Cases

Background

The results of recent trials have brought some confusion to the treatment strategy for renal artery stenosis (RAS). To evaluate the applicability of percutaneous transluminal renal angioplasty (PTRA) for RAS, we extracted the factors that may affect the effectiveness of PTRA from cases experienced at a hypertension center.

Methods and Results

We retrospectively assessed the blood pressure (BP) lowering effects and renoprotective effects in 50 consecutive patients that had hemodynamically significant RAS and had undergone PTRA and stenting during 2001–2005. Subjects were diagnosed with atherosclerotic RAS (42), fibromuscular dysplasia (6), or Takayasu disease (2). After PTRA, BP significantly lowered from 152.3/80.3 mmHg to 132.6/73.2 mmHg (p < 0.05), but the estimated glomerular filtration rate (eGFR) did not change significantly. There were no factors associated with the BP lowering effects of PTRA. The baseline resistive index (RI) was negatively correlated with the change in eGFR (p < 0.05). After correction for age, sex, BMI, and the dose of contrast medium, the association of RI with change in eGFR remained significant.

Conclusion

In cases with hemodynamically significant RAS, PTRA lowered BP but was not effective in improving renal function. Higher baseline RI may be a factor for predicting poor clinical course of renal function after PTRA.

Multimodality imaging of fibromuscular dysplasia

OBJECTIVE

Fibromuscular dysplasia (FMD) is an uncommon non-inflammatory and non-atherosclerotic cause of arterial disease that may result in stenosis, tortuosity, aneurysm, or dissection. The clinical presentation depends on the vascular bed involved and ranges from asymptomatic to multisystem disease and end organ ischemia. The purpose of this article is to review the role of imaging in patients with FMD with an emphasis on renal FMD. The relevant epidemiology, histopathology, imaging techniques, and interpretation of images will be discussed.

CONCLUSION

Renal artery FMD requires a high index of suspicion for accurate and prompt diagnosis and implementation of appropriate therapy. The treatment will vary based on clinical presentation and distribution of involvement. Noninvasive imaging with duplex ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) are reasonable alternatives for the depiction of FMD in comparison to catheter-directed angiography (CA). Patients with FMD are often treated by multispecialty practice including the interventional radiologist.

Resistant Hypertension due to Fibromuscular Dysplasia in a Young Male: A Rare Case Report

Fibromuscular Dysplasia (FMD) is a sporadic non-atherosclerotic disease. FMD has been established in nearly every arterial bed. However, the most frequent arteries affected are the renal and carotid arteries. Disease presentation may vary broadly, depending upon the arterial bed complication and the severity of illness. Hypertension, particularly resistant type, headache and dizziness are the most common presentations. String of beads appearance in angiographic views due to post-stenotic aneurysms is the characteristic view. It is most commonly described in young aged females; but in rare male cases has also been reported. Moreover, balloon angioplasty is standard and effective therapy for FMD. We present a young 28-year-old man who was referred for evaluation of resistant hypertension for nearly 3 years without comprehensive workup. The patient underwent renal artery angiography which confirmed beading narrowing of the right renal artery with significant stenosis at mid portion compatible with FMD; and balloon angioplasty was done. This case highlights that FMD should be kept in mind as a rare cause of resistant hypertension in young males; although it is most common in young females.

Surgical Treatment of Renal Fibromuscular Dysplasia in a Young Child

During a routine checkup in a 10-year-old male with Attention-Deficit Hyperactivity Disorder, blood pressure of 180/120 mmHg was found. Physical examination was completely normal. Ultrasound examination showed poststenotic dilatation of the left renal artery which was confirmed by CT-angiography showing a short, high grade stenosis of the left renal artery. Percutaneous Transluminal Angioplasty of the stenosis was not successful and therefore the stenosis was excised with reimplantation of the renal artery in the aorta. Pathological examination of the excised segment showed media-type Fibromuscular Dysplasia (FMD). Six years after surgery, the kidney is completely normal regarding size and function. There are no signs of restenosis of the left renal artery. Nevertheless, the hypertension remained although less severe and requiring less medication.

Optimal management of renal artery fibromuscular dysplasia

Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory angiopathy of unknown cause affecting medium-sized (most commonly renal) arteries and causing renovascular hypertension. The most common medial multifocal type of FMD (with the “string of beads” appearance) is more than four times more prevalent in females than in males. FMD accounts for up to 10% of cases of renovascular hypertension. Compared with patients with atherosclerotic renal artery stenosis, patients with FMD are younger, have fewer risk factors for atherosclerosis, and a lower occurrence of atherosclerosis in other vessels. The etiology is multifactorial, including vessel wall ischemia and smoking, as well as hormonal and genetic factors. Intra-arterial digital subtraction angiography is still the gold standard for exclusion or confirmation of renal artery stenosis caused by FMD, at least in young patients, who more often have lesions in branches of the renal artery. For FMD patients with atherosclerosis and those who are older (>50–55 years), significant renal artery stenosis may be confirmed or excluded with ultrasonography. The FMD lesion is typically truncal or distal, whereas atherosclerotic lesions are more often proximal or ostial. Treatment options are medical, endovascular (percutaneous transluminal renal angioplasty [PTRA]), and surgical. Invasive treatment should be considered when hypertension cannot be controlled with antihypertensive drugs and in patients with impaired renal function or ischemic nephropathy. PTRA has become the treatment of choice and normally yields good results, especially in unifocal disease and young patients. Pressure gradients are normally completely abolished, and there is no indication for stent placement. Surgical revascularization is indicated after PTRA complications; thrombosis, perforation, progressive dissection, repeated PTRA failure or restenosis. Centralization of handling is recommended.

Fibromuscular dysplasia of the renal artery as a cause of secondary hypertension

Fibromuscular dysplasia is an uncommon cause of secondary hypertension. When the resulting hypertension cannot be successfully treated with medications, balloon angioplasty has been shown to be successful by disrupting the "webs" of tissue in the renal artery. We present a case of secondary hypertension due to fibromuscular dysplasia and the successful treatment with balloon angioplasty.

MR in hypertension

Hypertension is a common systemic disorder affecting the cardiovascular system and kidneys with important morbidity and mortality. However, hypertension is often thought of by radiologists as an "invisible" disease. The aim of this article is to first review hypertension first in terms of its diagnosis, epidemiology and clinical importance. Second, those causes of secondary hypertension that may be diagnosed with MRI techniques are described along with the effects of hypertension on the cardiovascular system and kidneys that are demonstrable with MRI with particular emphasis on renovascular disease. Lastly the use of integrated MRI protocols to evaluate the hypertensive patient and areas for future research are considered.

Spectrum of renal findings in pediatric fibromuscular dysplasia and neurofibromatosis type 1

BACKGROUND

Fibromuscular dysplasia (FMD) and neurofibromatosis type 1 (NF1) are the most common causes of pediatric renal artery stenosis (RAS) in western countries, and characterization of their angiographic features could aid in an accurate diagnosis and in treatment.

OBJECTIVE

This study characterizes renal angiographic findings in pediatric fibromuscular dysplasia (FMD) and neurofibromatosis type 1(NF1).

MATERIALS AND METHODS

We reviewed 68 angiograms performed over 11 years on 43 children with renovascular hypertension (20 male, 23 females; ages 1 month to -19 years; median/average 9.8 years). Ten patients were diagnosed with NF1, and 33 had presumed FMD. The frequency, extent and distribution of lesions were determined and analyzed.

RESULTS

Stenosis was found in 91% of patients (n=39/43), with 86% showing stenosis of 1st or 2nd order arteries, and 12% distal to 2nd order. Stenoses in multiple 1st/2nd order arteries were found in 32% of patients, and 36/43 patients had 1-2 stenoses. The most common lesion was a ≤ 5 mm stenosis in a 1st/2nd order artery, in 42%. Mean percentage of stenosis in a 1st/2nd order vessel was 62%; ≥ 70% stenosis was found in 53%, and ≥ 90% stenosis in 29%. Bilateral disease was noted in 30% of patients. Intraparenchymal disease, distal to 2nd order branches, was seen in 30%. Aneurysms were seen in 28%, beading in 19% and collaterals in 51% (associated with ≥ 70% stenosis). Mid-aortic narrowing was seen in 16%, more often in patients with NF1.

CONCLUSION

We provide a descriptive characterization of renal angiographic findings in pediatric FMD and NF1.

Fibromuscular dysplasia presenting as a renal infarction: a case report

Introduction

Fibromuscular dysplasia is a non-atherosclerotic, non-inflammatory disease that most commonly affects the renal and internal carotid arteries.

Case presentation

We present the case of a 44-year-old Caucasian man who was admitted with complaints of loin pain and hypertension. A computed tomography scan of the abdomen revealed a right renal infarction with a nodular aspect of the right renal artery. Subsequent renal angiography revealed a typical 'string of beads' pattern of the right renal artery with thrombus formation. Oral anticoagulation was started and the secondary hypertension was easily controlled with anti-hypertensive drugs. At follow-up, our patient refused percutaneous transluminal renal angioplasty as a definitive treatment.

Conclusions

Fibromuscular dysplasia is the most common cause of renovascular hypertension in patients under 50 years of age. Presentation with renal infarction is rare.

In fibromuscular dysplasia, angioplasty has been proven to have, at least for some indications, an advantage over anti-hypertensive drugs. Therefore, hypertension secondary to fibromuscular dysplasia is the most common cause of curable hypertension.

Renovascular imaging in the NSF Era

The detection of the association between nephrogenic systemic fibrosis (NSF), a rare but potentially life-threatening disease only encountered in patients with severely impaired renal function, and the previous administration of some Gd-chelates has cast a shadow on the administration of Gd-chelates in patients with chronic renal failure. So far, contrast-enhanced MR-angiography (MRA) was considered the best diagnostic modality in patients with suspected renal disease. This review explores the most appropriate use of renal MRA with a focus on newly developed nonenhanced MRA techniques. Nonenhanced MRA techniques mainly based on SSFP with ECG-gating allow for acceptable spatial resolution to visualize at least the proximal parts of the renal arteries. In addition functional renal imaging techniques and their current clinical role are critically appreciated. J. Magn. Reson. Imaging 2009;30:1323-1334. (c) 2009 Wiley-Liss, Inc.

Assessment of renal artery fibromuscular dysplasia: angiography, intravascular ultrasound (with virtual histology), and pressure wire measurements

Fibromuscular dysplasia (FMD) of the renal arteries is classically associated with secondary hypertension in younger individuals, which may be treatable and even curable by percutaneous transluminal renal angioplasty. Angiography of these renal arteries often displays "beaded" luminal abnormalities. The angiographic findings, however, may not accurately reflect the severity or precise location of the intraluminal obstruction. We present a case of an older individual with longstanding hypertension and FMD, in whom the use of a coronary pressure wire and intravascular ultrasound enabled precise localization and treatment of the hemodynamically significant stenosis. Virtual histology of FMD in the renal vasculature is also reported.

Angioplasty for Renal Artery Fibromuscular Dysplasia in Older Hypertensive Patients

Aim: To describe the outcomes of treating patients with angioplasty who are older than 40 years with symptomatic/labile/refractory hypertension (HTN). Methods: Between1999 and 2005, 28 patients underwent angioplasty for renal fibromuscular dysplasia (FMD). Patients were excluded if they had concomitant atherosclerotic renal artery stenosis (n = 4) or less than 1 month follow-up (n = 8). Results: The study group included 16 Caucasians (21 procedures; mean age 65.5 10.8 years; females = 88%). The cardiovascular risk factors include HTN (n = 13), smoking (n = 1), diabetes (n = 2), dyslipidemia (n = 8). The HTN was characterized as refractory (n = 15, 12 were symptomatic) and new-onset in 1 patient. The technical success rate was 100%. Over a median period of 12.8 months (range: 1.0-85.8), 18 (95%) procedures ‘‘failed,’’ of which 8 (42%) within 1 month and the rest in 1 year. Conclusions: Angioplasty in symptomatic renal FMD in patients >40 years is associated with poor outcomes possibly due to early restenosis.

Current approaches to renovascular hypertension

This article examines the status regarding prevalence, mechanisms, clinical manifestations and management of renovascular hypertension at this point in time. It should be viewed as a work in progress. As with most complex conditions, clinicians must integrate the results of published literature studies while considering each patient's specific features and comorbid disease risks. Beyond identifying renovascular disease as a cause of secondary hypertension, one must manage renal artery stenosis (RAS) itself as an atherosclerotic vascular complication. This disease warrants follow-up regarding progression and potential for ischemic tissue injury. These elements often determine the role and timing for revascularization. In this respect, atherosclerotic renal artery stenosis is analogous to progressive carotid or aortic aneurysmal disease.

Renovascular hypertension: an update

Renovascular hypertension, the most common remediable cause of elevated blood pressure, is a controversial topic, but most authorities agree on several principles. The absolute risk of renovascular hypertension for a specific patient can be estimated using only clinical information, thereby sparing many patients further expensive and potentially dangerous evaluations. Patients with a high absolute risk of renovascular hypertension should have angiography only if they are willing to undergo revascularization if warranted. A screening test (captopril renography, Doppler ultrasonography, magnetic resonance angiography, or computed tomography) is recommended for those with an intermediate absolute risk. Angioplasty should be offered to patients with fibromuscular dysplasia. Whether intensive medical therapy (including an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker) for atherosclerotic renovascular hypertension is improved by angioplasty plus stent placement may be answered by ongoing studies, the largest of which may be the National Institutes of Health-funded Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial.

Percutaneous transluminal angioplasty of renal artery fibromuscular dysplasia: mid-term results

Objective

To evaluate mid-term imaging, clinical follow-up, and restenosis rates from patients that had undergone percutaneous transluminal renal artery angioplasty (PTRA) for symptomatic renal artery fibromuscular dysplasia (FMD).

Materials and Methods

Between March 1999 and July 2006, 16 consecutive renal artery FMD patients underwent PTRA for poorly controlled hypertension. The patients were enrolled into this retrospective study after receiving 19 primary and four secondary PTRAs in 19 renal artery segments. Follow-up monitoring of blood pressure, use of antihypertensive medication, and the serum creatinine level after PTRA were assessed at 1, 3, 6, 9, 12 months, and each following year. The degree of restenosis was evaluated with computed tomographic angiography (CTA) after PTRA at 6, 12 months, and every year if possible. Technical and clinical success rates for the treatment of FMD, and restenosis rates for the renal artery were evaluated.

Results

The technical success rate for primary PTRA was 79% (15/19) and the complication rate was 16% (3/19). Hypertension improved in 80% (12/15) of the patients after four weeks follow-up, and was finally cured or improved in 93% (14/15) during the mean follow-up period of 23.6 months. There was a cumulative 22% (4/18) restenosis rate during the follow-up period. All of the patients were treated with a second PTRA without complications and all of the patients were cured of hypertension after the second PTRA.

Conclusion

Percutaneous transluminal renal artery angioplasty for clinically symptomatic renal FMD is technically and clinically successful and safe to perform. For all patients with restenosis, there was a good response after undergoing a second PTRA.

Management of renal artery stenosis - an update

The role of the renal vasculature in eliciting renovascular hypertension (RVH) was established in 1934, when Goldblatt et al. [1] in a classical experimental study demonstrated that partial obstruction of the renal artery increased mean arterial blood pressure (BP). The pathophysiology of renal artery stenosis (RAS) is incompletely understood but has been postulated to be related to increased afterload from neurohormonal activation and cytokine release [2]. Atherosclerotic RAS (ARAS) is increasingly diagnosed in the expanding elderly population, which also has a high prevalence of arterial hypertension. There is still considerable uncertainty concerning the optimal management of patients with RAS. Many hypertensive patients with RAS have co-existing essential hypertension and furthermore, it is often difficult to determine to what degree the RAS is responsible for the impairment of renal function. There are three possible treatment strategies: medical management, surgery, or percutaneous transluminal renal angioplasty (PTRA) with or without stent implantation. The use of stents has improved the technical success rate of PTRA and also led to lower risk of restenosis, in particular for ostial RAS. PTRA with stenting has therefore replaced surgical revascularisation for most patients with RAS and has led to a lower threshold for intervention. The treatment of choice to control hypertension in fibromuscular dysplasia (FMD) is generally accepted to be PTRA [3]. In ARAS, on the other hand, the benefits with PTRA are less clear [4] and the challenge to identify which patients are likely to benefit from revascularisation remains unknown.

Branch renal artery repair with cold perfusion protection

PURPOSE

This retrospective review describes the use and clinical outcome of cold perfusion protection during branch renal artery (RA) repair in 77 consecutive patients.

METHODS

From July 1987 through November 2006, 874 patients had open operative RA repair to 1312 kidneys. Seventy-seven patients (62 women, 15 men; mean age, 44 +/- 17 years) had branch RA reconstruction using ex vivo or in situ cold perfusion protection for 78 kidneys. Demographic data and surgical technique were examined. Blood pressure response and renal function were estimated. Patency of repair was determined by angiography and renal duplex ultrasound (RDUS) imaging. Primary RA patency was estimated by life-table methods.

RESULTS

Seventy-eight RAs were repaired using ex vivo (49 kidneys) or in situ (29 kidneys) cold perfusion protection. Bilateral RA repair was performed in eight patients, with 13 repairs to solitary kidneys. RA disease included aneurysm (RAA) in 50, fibromuscular dysplasia (FMD) in 37, atherosclerosis in 5, and arteritis in 2; 16 patients had both FMD and RAA. Hypertension was present in 93.5% (mean blood pressure, 184 +/- 35/107 +/- 19 mm Hg; mean of 1.9 +/- 1.1 drugs). RA repair included bypass using saphenous vein in 69, hypogastric artery in 3, polytetrafluoroethylene (PTFE) in 2, composite vein/PTFE in 2, cephalic vein in 1, or aneurysmorrhaphy in 1. The eight bilateral RA repairs were staged. One patient required bilateral cold perfusion protection. One planned nephrectomy was performed at the time of contralateral ex vivo reconstruction. No primary nephrectomies were required for intended reconstruction. Each RA reconstruction required branch dissection and reconstruction (mean of 2.8 +/- 1.6 branches were repaired). Mean cold ischemia time was 125 +/- 40 minutes. Each kidney was reconstructed in an orthotopic fashion. Five early failures of repair required three nephrectomies and one operative revision. Based on postoperative angiography or RDUS, or both, primary patency of RA repair at 12 months was 85% +/- 5%; assisted primary patency was 93% +/- 4%. Among patients with preoperative hypertension, 15% were cured, 65% were improved, and 20% were considered failed. Early renal function was improved in 35%, unchanged in 48%, and worse in 17%. Four patients had perioperative acute tubular necrosis. No patient progressed to dialysis-dependence.

CONCLUSION

Both ex vivo and in situ cold perfusion protection extend the safe renal ischemia time for complex branch RA repair and avoid the need for nephrectomy.

Fibromuscular Dysplasia: An Uncommon Cause of Secondary Hypertension

Fibromuscular dysplasia is a noninflammatory vascular disease that commonly affects the distal two thirds of the renal artery and branch vessels, but occasionally involves other arteries. Progression of stenosis occurs in 16%-38% of renal arteries. Although the etiology is unknown, genetic studies suggest a relationship to the angiotensin-converting enzyme I allele. Thin, young Caucasian women without a family history of hypertension are most commonly affected. An abdominal or flank systolic-diastolic bruit is an important clue for the diagnosis. Most noninvasive screening tests are not sensitive or reproducible to be used to rule out renal artery stenosis, but digital subtraction renal angiography usually confirms the diagnosis. Percutaneous renal artery angioplasty is the treatment of choice, but may not result in normalization of blood pressure if diagnosis is delayed. Since restenosis occurs, continued follow-up is necessary.

Renovascular hypertension update

Hypertension detected in patients with renovascular disease poses a major clinical challenge. The rapid expansion of noninvasive imaging, effective antihypertensive drug therapy, and endovascular interventional procedures combine to make optimal management a moving target. Renal arterial disease accelerates the development of hypertension associated with activation of multiple pressor systems and accelerated target organ injury. Younger individuals with fibromuscular lesions often respond well to renal revascularization with minor associated risks. Care must be taken in cases of complex vascular anomalies, such as renal artery aneurysms. Atherosclerotic renal artery stenosis is detected more commonly than ever before and affects more than 85% of patients referred for revascularization. Most are older patients with long-standing hypertension, diabetes, and pre-existing complications of vascular disease. The benefits of extensive workup and intervention in this group of patients are controversial. Antihypertensive drug therapy is most effectively achieved with drugs that block the renin-angiotensin system, but most require multiple agents. Selection of patients for renal revascularization in this group is far more controversial than with fibromuscular disease. Several small trials failed to identify major benefits with renal artery angioplasty as compared to closely monitored drug therapy, although crossover rates from medical to interventional arms were high. The Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) seeks to randomly assign subjects with proven, high-grade renal artery lesions to optimal medical management with and without stenting. This important trial employs distal embolic protection to prevent deterioration of renal function. Understanding the optimal role for renal revascularization depends heavily upon the successful conduct of such trials.

Fibromuscular dysplasia of renal arteries: Percutaneous revascularization based on hemodynamic assessment with a pressure measurement guidewire

Fibromuscular dysplasia (FMD) leading to renal artery stenosis and hypertension is one of the most common treatable causes of secondary hypertension. However, frequently it can be difficult to judge the anatomical severity of a stenotic lesion with various noninvasive and invasive imaging modalities. We present two patients with poorly controlled hypertension and FMD affecting the renal arteries, in whom there were no anatomically significant stenoses by renal magnetic resonance angiography or selective renal artery angiography. Utilizing a 0.014'' high fidelity micromanometer tipped PressureWire XT (Radi, Reading, MA), to measure intravascular pressure gradients throughout the diseased renal arteries, we identified physiologically significant stenoses, and successfully treated both patients with percutaneous transluminal angioplasty.

Pathophysiology of renovascular hypertension

Studies of the renin-angiotension system and the effects of pharmacologic blockade have enhanced our understanding of renovascular hypertension. A critical degree of arterial stenosis produces kidney ischemia sufficient to activate this hormonal system, whose actions include vasoconstriction and sodium retention. Accurate clinical evaluation may depend upon recognizing the differences in pathophysiology between "one-kidney" and "two-kidney" forms and the dynamic nature of this condition.