Treatment of renal artery fibromuscular dysplasia with balloon angioplasty: a prospective follow-up study

Unique presentation of renovascular hypertension due to fibromuscular dysplasia

A 21-year-old female with a history of right nephrectomy due to trauma presented with several years of multidrug-resistant hypertension. Her workup included negative findings from autoimmune and vasculitides panels and urine catecholamine testing. Computed tomography showed an acute hairpin turn of her left renal artery. Intraoperatively, the artery demonstrated kinking with exhalation. She underwent excision of the diseased portion of the renal artery and an end-to-end anastomosis. Final pathologic examination demonstrated fibromuscular dysplasia. This is a unique case of mechanical artery kinking combined with fibromuscular dysplasia contributing to renovascular hypertension, for which open surgery was beneficial at improving the patient's hypertension.

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.

Renal artery stenosis

Renal artery stenosis is the most common secondary cause of hypertension and predominantly caused by atherosclerosis. In suspected patients, a non-invasive diagnosis with ultrasound is preferred. Asymptomatic, incidentally found RAS does not require revascularization. In symptomatic patients requiring revascularization, renal artery stenting is the preferred therapy. Selecting appropriate patients for revascularization requires careful consideration of lesion severity and is optimized with a multidisciplinary team. All patients with atherosclerotic RAS should be treated with guideline-directed medical therapy, including hypertension control, diabetes control, statins, antiplatelet therapy, smoking cessation and encouraging activity.

The Society for Vascular Surgery practice guidelines on follow-up after vascular surgery arterial procedures

Although follow-up after open surgical and endovascular procedures is generally regarded as an important part of the care provided by vascular surgeons, there are no detailed or comprehensive guidelines that specify the optimal approaches with regard to testing methods, indications for reintervention, and follow-up intervals. To provide guidance to the vascular surgeon, the Clinical Practice Council of the Society for Vascular Surgery appointed an expert panel and a methodologist to review the current clinical evidence and to develop recommendations for follow-up after vascular surgery procedures. For those procedures for which high-quality evidence was not available, recommendations were based on observational studies, committee consensus, and indirect evidence. Recognizing that there are numerous published reports on the role of duplex ultrasound for surveillance of infrainguinal vein bypass grafts, the Society commissioned a systematic review and meta-analysis on this topic. The panel classified the strength of each recommendation and the corresponding quality of evidence on the basis of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system: recommendations were graded either strong or weak, and the quality of evidence was graded high, moderate, or low. The resulting recommendations represent a wide variety of open surgical and endovascular procedures involving the extracranial carotid artery, thoracic and abdominal aorta, mesenteric and renal arteries, and lower extremity arterial revascularization. The panel also identified many areas in which there was a lack of high-quality evidence to support their recommendations. This suggests that there are opportunities for further clinical research on testing methods, threshold criteria, and the role of surveillance as well as on the modes of failure and indications for reintervention after vascular surgery procedures.

Surgical revascularization of bilateral renal artery stenosis due to fibromuscular dysplasia

Fibromuscular dysplasia (FMD) is a noninflammatory disease affecting small- and medium-sized arteries of the renal and the carotids. It affects the renal arteries in nearly 60%–75% cases. The primary clinical manifestation of renal FMD is hypertension. Medial fibroplasia represents the most common dysplastic lesion. We report two cases who presented with hypertension and renal insufficiency and on evaluation was found to have bilateral renal artery stenosis. Stenting of the renal vessels was not possible due to the narrowed caliber of the vessel and inability to cannulate the renal arteries. They underwent renal artery revascularization with a splenorenal end to end anastomosis. The renal parameters and blood pressure of both the patients stabilized subsequently. Renal revascularization can be a good option for patient having failed angioplasty with stenting.

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.

Renal artery stenosis - an update

Renal artery stenosis (RAS) is a common form of peripheral arterial disease. The most common cause of RAS is atherosclerosis. It is predominantly unilateral. The pathophysiologic mechanism stems from renal underperfusion resulting in the activation of the renin- angiotensin-aldosterone pathway. Even though the majority of patients with RAS are asymptomatic, it can clinically present with hypertension, nephropathy and congestive heart failure. This progressive disease can lead to resistant hypertension and end stage kidney failure. Screening patients for RAS with either Doppler ultrasonography, computed tomographic angiography, or magnetic resonance angiography is preferred. Adequate blood pressure control, goal-directed lipid-lowering therapy, smoking cessation, and other preventive measures form the foundation of management of patients with RAS. Catheter-based percutaneous revascularization with angioplasty and stenting showed modest clinical benefit for patients in small retrospective studies, but data from randomized clinical trials failed to confirm these beneficial results. The current ongoing Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial may provide more concrete data regarding the role of stenting in RAS. Surgical revascularization is considered only if catheter-based revascularization is unsuitable or unsuccessful. The American College of Cardiology/American Heart Association guidelines on evaluation and management of patients with RAS provide the framework for determining individualized assessment and treatment plans for patients with RAS.

Percutaneous renal artery angioplasty and stenting: indications, technique and results

BACKGROUND

Percutaneous interventions for renal arterial disease can be used to treat a variety of conditions including both atherosclerotic and non-atherosclerotic renal artery stenosis (RAS) as well as endovascular management of renal artery aneurysms (RAA).

AIM

We sought to examine the indications, techniques and results of percutaneous renal angioplasty and stenting in our institution over a 6-year period and review the current evidence for practice.

METHODS

Patient demographics, procedure indications, technical procedural details, complications, baseline and follow-up renal profile indices were analysed.

RESULTS

The most common indication for intervention was atherosclerotic RAS (69.2%) followed by RAS secondary to fibromuscular dysplasia (15.3%) and RAA (15.3%). There was a 100% technical success in our cohort of patients. The majority of patients (84.6%) had cross-sectional imaging in the form of computed tomography or magnetic resonance angiography prior to intervention.

CONCLUSION

When performed in appropriate settings following close liaison with referring physicians, percutaneous renal angioplasty and stenting remains an important treatment modality for renovascular disease.

Current opinions in renovascular hypertension

Renal artery stenosis and renovascular hypertension are important considerations in patients with hypertension that is difficult to control. The diagnosis may also have prognostic significance for progressive renal disease. The most common causes of renal artery stenosis are atherosclerotic disease and fibromuscular dysplasia. The pathophysiology of renal artery stenosis is reviewed, and the pros and cons of various imaging studies in the appropriate clinical setting are discussed. Treatment includes aggressive control of hypertension, dealing with associated cardiac risk factors, and angioplasty or surgery in specific circumstances.

A unique case of renal artery fibromuscular dysplasia

Fibromuscular dysplasia (FMD) is a noninflammatory, nonatherosclerotic disorder resulting in arterial stenosis. Here, a unique case of renal artery FMD (RA FMD) is presented. With the use of angiograpic and intravascular ultrasound (IVUS) imaging modalities, a patient was diagnosed with two distinct types of FMD. Until now, the prevalence of FMD has been underestimated due to limitations in diagnostic modalities. Clinically, the correct identification of RA FMD is essential because these patients have been shown to respond to revascularization therapy with significant improvement in blood pressure whereas renal artery lesions secondary to other etiologies such as atherosclerosis have yet to show the same consistent response. Further, the presence of two subtypes of FMD in a single patient may suggest the possibility of genetic factors that predispose certain vessels to certain subtypes of FMD.

Efficacy of renal revascularization in a patient with fibromuscular renal artery stenosis and heart failure

We report the case of a 65-year-old woman with a solitary kidney who developed hypertension due to renal artery stenosis caused by fibromuscular dysplasia. In addition, an echocardiogram revealed severe left ventricular systolic and diastolic dysfunction. Despite antihypertensive drug treatment that included diuretics, her serum concentration of brain natriuretic peptide was persistently elevated and associated with progressive worsening of renal function. She underwent iliac artery to renal artery bypass grafting. After the surgery, blood pressure control was good, the serum concentration of brain natriuretic peptide decreased, and left ventricular diastolic function improved. This case exemplifies the efficacy of renal revascularization in patients with fibromuscular renal artery stenosis and heart failure.

Renovascular hypertension and ischemic nephropathy

Renovascular disease remains among the most prevalent and important causes of secondary hypertension and renal dysfunction. Many lesions reduce perfusion pressure including fibromuscular diseases and renal infarction, but most are caused by atherosclerotic disease. Epidemiologic studies establish a strong association between atherosclerotic renal-artery stenosis (ARAS) and cardiovascular risk. Hypertension develops in patients with renovascular disease from a complex set of pressor signals, including activation of the renin-angiotensin system (RAS), recruitment of oxidative stress pathways, and sympathoadrenergic activation. Although the kidney maintains function over a broad range of autoregulation, sustained reduction in renal perfusion leads to disturbed microvascular function, vascular rarefaction, and ultimately development of interstitial fibrosis. Advances in antihypertensive drug therapy and intensive risk factor management including smoking cessation and statin therapy can provide excellent blood pressure control for many individuals. Despite extensive observational experience with renal revascularization in patients with renovascular hypertension, recent prospective randomized trials fail to establish compelling benefits either with endovascular stents or with surgery when added to effective medical therapy. These trials are limited and exclude many patients most likely to benefit from revascularization. Meaningful recovery of kidney function after revascularization is limited once fibrosis is established. Recent experimental studies indicate that mechanisms allowing repair and regeneration of parenchymal kidney tissue may lead to improved outcomes in the future. Until additional staging tools become available, clinicians will be forced to individualize therapy carefully to optimize the potential benefits regarding both blood pressure and renal function for such patients.

Efficacy of revascularization for renal artery stenosis caused by fibromuscular dysplasia: a systematic review and meta-analysis

In patients with fibromuscular dysplasia and renal artery stenosis, renal artery revascularization has been used to cure hypertension or to improve blood pressure control. To provide an up-to-date assessment of the benefits and risks associated with revascularization in this condition, we performed a systematic review of studies in which hypertensive patients with fibromuscular dysplasia renal artery stenosis underwent percutaneous transluminal renal angioplasty or surgical reconstruction. We assessed how often periprocedural complications and hypertension cure and improvement occurred. We selected 47 angioplasty studies (1616 patients) and 23 surgery studies (1014 patients). Combined rates of hypertension cure, defined according to the criteria in each study, after angioplasty or surgery were estimated to be 46% (95% CI: 40% to 52%) and 58% (95% CI: 53% to 62%), respectively, with substantial variations across studies. The probability of being cured was negatively associated with patient age and time of publication. Cure rates using current definitions of hypertension cure (blood pressure <140/90 mm Hg without treatment) were only 36% and 54% after angioplasty and surgery, respectively. The combined risks of periprocedural complications were 12% and 17% after angioplasty and surgery, respectively, with less major complications after angioplasty than surgery (6% versus 15%). In conclusion, angioplasty or surgical revascularization yielded moderate benefits in patients with fibromuscular dysplasia renal artery stenosis, with substantial variation across studies. The blood pressure outcome was strongly influenced by patient age.

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.

Revascularization of swine renal artery stenosis improves renal function but not the changes in vascular structure

Renal revascularization by percutaneous transluminal angioplasty improves blood pressure and stenotic kidney function in selected groups of patients, but the reversibility of intrarenal and microvascular remodeling remains unknown. Here, we tested the hypothesis that renal angioplasty improves the function and structure of renal microcirculation in experimental chronic renal artery stenosis. Stenotic kidney function, hemodynamics, and endothelial function were assessed in vivo in pigs after 10 weeks of unilateral renal artery stenosis. Renal microvascular remodeling, angiogenic pathways, and fibrosis were measured ex vivo. Angioplasty and stenting carried out 4 weeks before measurement decreased blood pressure, improved glomerular filtration rate, and improved microvascular endothelial function. It also promoted the expression of angiogenic factors and decreased renal apoptosis due to stenosis, compared with a sham intervention. The spatial density of renal microvessels, however, was partially improved after angioplasty. Renal blood flow was incompletely restored compared with the kidneys of sham-treated animals, as was interstitial fibrosis. Renal microvascular media-to-lumen ratio remained unchanged by angioplasty. Thus, our study shows that revascularization of a stenotic renal artery restores the glomerular filtration rate and renal endothelial function 4 weeks later. Renal hemodynamics and structure, however, are incompletely resolved.

Current options for the treatment of resistant hypertension

Patients with resistant hypertension are those who have uncontrolled blood pressure despite use of three or more antihypertensive medications, or those who require four or more medications to achieve control. When evaluating resistant hypertension it is important to rule out pseudoresistant hypertension that may result from factors including poor blood pressure measurement technique and the white coat effect. Potential contributing factors should be identified and reversed if possible, including obesity, excess alcohol intake and use of interfering medications such as NSAIDS, sympathomimetics and oral contraceptives. Modification of lifestyle factors such as weight loss, sodium restriction and physical activity is paramount for treatment success. Secondary causes of hypertension are common in this patient group and, therefore, appropriate screening tests should be carried out as necessary. Pharmacologic therapy is centered on combination therapy of medications from different mechanisms of action, especially diuretics, which are essential in maximizing antihypertensive effects. The role of mineralocorticoid antagonists is expanding, especially in patients with obstructive sleep apnea and obesity where aldosterone excess may be implicated. Finally, when appropriate, specialist referral may facilitate blood pressure reduction and the ability to meet target blood pressure goals.

Resistant hypertension: diagnosis, evaluation, and treatment: a scientific statement from the American Heart Association Professional Education Committee of the Council for High Blood Pressure Research

Resistant hypertension is a common clinical problem faced by both primary care clinicians and specialists. While the exact prevalence of resistant hypertension is unknown, clinical trials suggest that it is not rare, involving perhaps 20% to 30% of study participants. As older age and obesity are 2 of the strongest risk factors for uncontrolled hypertension, the incidence of resistant hypertension will likely increase as the population becomes more elderly and heavier. The prognosis of resistant hypertension is unknown, but cardiovascular risk is undoubtedly increased as patients often have a history of long-standing, severe hypertension complicated by multiple other cardiovascular risk factors such as obesity, sleep apnea, diabetes, and chronic kidney disease. The diagnosis of resistant hypertension requires use of good blood pressure technique to confirm persistently elevated blood pressure levels. Pseudoresistance, including lack of blood pressure control secondary to poor medication adherence or white coat hypertension, must be excluded. Resistant hypertension is almost always multifactorial in etiology. Successful treatment requires identification and reversal of lifestyle factors contributing to treatment resistance; diagnosis and appropriate treatment of secondary causes of hypertension; and use of effective multidrug regimens. As a subgroup, patients with resistant hypertension have not been widely studied. Observational assessments have allowed for identification of demographic and lifestyle characteristics associated with resistant hypertension, and the role of secondary causes of hypertension in promoting treatment resistance is well documented; however, identification of broader mechanisms of treatment resistance is lacking. In particular, attempts to elucidate potential genetic causes of resistant hypertension have been limited. Recommendations for the pharmacological treatment of resistant hypertension remain largely empiric due to the lack of systematic assessments of 3 or 4 drug combinations. Studies of resistant hypertension are limited by the high cardiovascular risk of patients within this subgroup, which generally precludes safe withdrawal of medications; the presence of multiple disease processes (eg, sleep apnea, diabetes, chronic kidney disease, atherosclerotic disease) and their associated medical therapies, which confound interpretation of study results; and the difficulty in enrolling large numbers of study participants. Expanding our understanding of the causes of resistant hypertension and thereby potentially allowing for more effective prevention and/or treatment will be essential to improve the long-term clinical management of this disorder.

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.

Failure and success of percutaneous angioplasty in a hypertensive child with bilateral renal artery stenosis

We describe the clinical course of a 5-year-old girl with severe arterial hypertension that was uncontrollable with antihypertensive medication. Renal angiography revealed bilateral renal artery stenoses. Because percutaneous transluminal renal angioplasty (PTRA) failed to dilate the stenotic lesions, a renal artery bypass grafting in both renal arteries was performed. The patient remained normotensive for 7 months, and after that the arterial pressure increased again. Digital subtraction angiography demonstrated stenosis at the peripheral and central anastomosis of the vein graft that was used for revascularization of the left kidney. PTRA was decided on and successful patency was achieved. The patient has now been normotensive for a period of 5 years.

Resistant hypertension: diagnosis, evaluation, and treatment. A scientific statement from the American Heart Association Professional Education Committee of the Council for High Blood Pressure Research

Resistant hypertension is a common clinical problem faced by both primary care clinicians and specialists. While the exact prevalence of resistant hypertension is unknown, clinical trials suggest that it is not rare, involving perhaps 20% to 30% of study participants. As older age and obesity are 2 of the strongest risk factors for uncontrolled hypertension, the incidence of resistant hypertension will likely increase as the population becomes more elderly and heavier. The prognosis of resistant hypertension is unknown, but cardiovascular risk is undoubtedly increased as patients often have a history of long-standing, severe hypertension complicated by multiple other cardiovascular risk factors such as obesity, sleep apnea, diabetes, and chronic kidney disease. The diagnosis of resistant hypertension requires use of good blood pressure technique to confirm persistently elevated blood pressure levels. Pseudoresistance, including lack of blood pressure control secondary to poor medication adherence or white coat hypertension, must be excluded. Resistant hypertension is almost always multifactorial in etiology. Successful treatment requires identification and reversal of lifestyle factors contributing to treatment resistance; diagnosis and appropriate treatment of secondary causes of hypertension; and use of effective multidrug regimens. As a subgroup, patients with resistant hypertension have not been widely studied. Observational assessments have allowed for identification of demographic and lifestyle characteristics associated with resistant hypertension, and the role of secondary causes of hypertension in promoting treatment resistance is well documented; however, identification of broader mechanisms of treatment resistance is lacking. In particular, attempts to elucidate potential genetic causes of resistant hypertension have been limited. Recommendations for the pharmacological treatment of resistant hypertension remain largely empiric due to the lack of systematic assessments of 3 or 4 drug combinations. Studies of resistant hypertension are limited by the high cardiovascular risk of patients within this subgroup, which generally precludes safe withdrawal of medications; the presence of multiple disease processes (eg, sleep apnea, diabetes, chronic kidney disease, atherosclerotic disease) and their associated medical therapies, which confound interpretation of study results; and the difficulty in enrolling large numbers of study participants. Expanding our understanding of the causes of resistant hypertension and thereby potentially allowing for more effective prevention and/or treatment will be essential to improve the long-term clinical management of this disorder.

When ballooning alone is enough: successful treatment of hypertension secondary to renal artery fibromuscular dysplasia using angioplasty

A case of hypertension secondary to renal artery fibromuscular dysplasia (FMD), successfully treated by balloon angioplasty is presented to highlight that for this specific condition balloon angioplasty remains the treatment of choice.

Renal Artery Stenosis and Cardiovascular Risk

Atherosclerotic renal artery stenosis is the most common disease of the renal arteries and may lead to ischemic renal disease and hypertension. A close relationship exists between renal and cardiovascular disease, as they often occur concomitantly, and abnormalities in either system can cause disease and determine clinical outcome in the other. Renovascular disease is gaining recognition as a potentially important risk factor for cardiovascular morbidity and mortality. This article explores the association between atherosclerotic renal artery stenosis and the cardiovascular system.

Interventional management of renal vascular origin hematuria

Several renal vascular pathological processes have been associated with hematuria. These include renal artery aneurysm (RAA), fibromuscular dysplasia (FMD), renal nutcracker syndrome (RNS), renal arteriovenous malformation, renal vasculitis, and renal artery or vein thrombosis. We present an unusual case of hematuria in a patient eventually diagnosed with RAA, FMD, and RNS. Percutaneous therapy, including endovascular coiling, percutaneous transluminal angioplasty, and stent placement were used to address the underlying pathology. The differential diagnosis, pathophysiology, and surgical and interventional management of these renal vascular disorders are reviewed.

Resistant or Difficult‐to‐Treat Hypertension

Resistant hypertension, defined as uncontrolled hypertension on three medications, is becoming an increasingly common problem. In most cases, blood pressure remains elevated because of persistently high systolic blood pressure levels. Common characteristics of patients with resistant hypertension include older age, obesity, excessive dietary salt ingestion, and presence of sleep apnea. The evaluation of patients with resistant hypertension is focused on identifying contributing and secondary causes of hypertension. Treatment should include both lifestyle changes (weight loss, exercise, dietary salt restriction) and the use of effective multidrug regimens, including a diuretic. Recent data indicate that aldosterone antagonists may be effective when added to existing antihypertensive regimens even in the absence of primary aldosteronism.

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.

Angioplasty for renovascular hypertension in children: 20-year experience

OBJECTIVE

Our aim was to evaluate the clinical outcomes, safety, and efficacy of percutaneous transluminal angioplasty for renovascular hypertension in children.

METHODS

A retrospective review of data for all children with renovascular hypertension who underwent percutaneous transluminal angioplasty at a single center between 1984 and 2003 was performed. Patients with renal transplants and inflammatory multisystem diseases were excluded.

RESULTS

Thirty-three children, 1.9 to 17.9 years of age (median: 10.3 years), underwent renal angioplasty and/or stenting. Underlying syndromes were present in 10. On angiograms, 16 had bilateral renal artery stenosis, 15 intrarenal disease, 8 aortic stenosis, and 7 cerebrovascular disease. Forty-eight percutaneous transluminal angioplasty procedures were performed, including 15 stenting procedures. There was a high rate of restenosis after stenting (7 of 19 cases, compared with 2 of 27 cases after balloon dilation). Outcomes were cured (ie, blood pressure normal without treatment) for 9 patients, improved blood pressure with same or reduced treatment for 7, blood pressure maintained in >95th percentile because of cerebrovascular disease for 2, no change in blood pressure despite technical success for 10, and technical failure for 5. Blood pressure control improved in 11 of 13 children who had main renal artery disease alone and in 6 of 20 with associated intrarenal disease or stenoses in other vascular beds. There was 1 procedure-related death and 5 minor complications.

CONCLUSIONS

Angioplasty produced clinically worthwhile improvement for approximately 50% of patients. High incidence rates of extrarenal involvement and intrarenal disease and a high restenosis rate after stenting accounted for poor blood pressure control in the rest.

Treatment of severe renal artery stenosis by percutaneous transluminal renal angioplasty and stent implantation: review of the pediatric experience: apropos of two cases

The clinical course of two children with mid-aortic syndrome and renal artery stenosis (RAS) who suffered from severe arterial hypertension is described. Hypertension was uncontrollable by antihypertensive medication and was managed by percutaneous transluminal renal angioplasty (PTRA) with stent implantation. The pediatric experience with PTRA is limited, and there are only few cases reported with additional stent implantation. Complications of these procedures are well known from experience with adult patients. However, since surgical revascularization may be technically difficult especially in small children, PTRA with or without stenting should be considered as a valuable treatment option in pediatric RAS.

New intrarenal echo-Doppler velocimetric indices for the diagnosis of renal artery stenosis

We aimed at comparing the positive and negative predictive values (PPV, NPV) of several intrarenal velocimetric indices for revealing the presence of renal artery stenosis (RAS) among hypertensive patients who underwent a renal angiography for the clinical suspicion of renovascular hypertension. In 106 patients (200 kidneys), the pulsatility index (PI) and resistive index (RI), the acceleration time (AT), and the mean systolic acceleration (ACC(sys)) were evaluated. In addition, the maximal systolic acceleration (ACC(max)), that is, the maximal slope of the acceleration phase, and the maximal acceleration index (AI(max)), that is, the ratio between ACC(max) and the relative peak systolic velocity, were calculated. On angiography, we found that 56 (28%) of the 200 arteries had a greater than 60% RAS. PI and RI had an NPV below 75%, whereas AT, ACC(sys), ACC(max), and AI(max) had an NPV always above 95%. However, ACC(max), and AI(max), at their best cutoff limits, had higher PPV than ACC(sys) and AT (60 and 70% vs 45 and 51%, respectively). Thus, in a cohort of patients with a high prevalence of RAS, PI and RI failed to reach an NPV adequate for a screening test. In contrast, all the acceleration indices we tested had a sufficiently high NPV but AI(max) appears superior to the others because of higher PPV. We propose the evaluation of AI(max) as an additional screening test in patients with hypertension and the clinical suspicion of RAS.

An update on renovascular hypertension

Renovascular hypertension (RVH) represents a secondary and potentially remediable form of hypertension. Elevated blood pressure is only one of a broad array of pathophysiologic consequences that are associated with decreased renal perfusion. Our ability to accurately and noninvasively detect stenotic lesions within the renal artery is growing. However, functional assessment of renal parenchyma and hemodynamic significance of renal artery lesions is still limited. Advances in endovascular techniques spurred interest in the concept of ischemic nephropathy and the effect of renal artery revascularization on renal function. Despite the relative frequency of atherosclerotic renal artery stenosis (ARAS), there currently is no consensus on the most appropriate therapy. In this article, we focus on the two most common causes of RVH, ARAS and fibromuscular dysplasia. We discuss the therapeutic strategies, disease mechanisms, clinical findings, evolving trends, and developments.

Challenges in the diagnosis and management of renal artery stenosis

Renal artery stenosis (RAS) is a common cause of secondary hypertension, with the activation of the renin-angiotensin-aldosterone system being the pathophysiologic hallmark of the disease. Renovascular hypertension, ischemic nephropathy, proteinuria, and flash pulmonary edema are the main clinical syndromes associated with RAS. The prevalence of RAS is on the rise, owing to an increasing prevalence of diabetes and atherosclerotic disease among our aging population. This rise in RAS prevalence poses major challenges for clinicians making diagnostic and treatment decisions. Although renal angioplasty is of proven benefit in fibromuscular dysplasia, randomized trials in atherosclerotic RAS have not shown any advantage for revascularization over medical therapy in terms of blood pressure control or renal function preservation. Angioplasty and surgical interventions should be reserved for patients with preserved kidney size and hemodynamically significant stenosis.

Validation of a prediction rule for renal artery stenosis

OBJECTIVES

We previously developed a prediction rule to estimate the probability of renal artery stenosis. This rule should be validated before it can be used reliably to select hypertensive patients for renal angiography. We determined the validity of the prediction rule in recent patients and in other settings.

DESIGN

We studied three aspects of validity (agreement between predicted and observed probability of stenosis, discriminative ability, and clinical usefulness) in 180 consecutive patients with drug-resistant hypertension and normal or mildly impaired renal function, who visited six hypertension clinics of academic and community hospitals in the Netherlands. Thirty-five patients (19%) had a significant stenosis.

RESULTS

The clinical characteristics in the rule (age, sex, vascular disease, recent onset of hypertension, smoking, body mass index, abdominal bruit, serum creatinine concentration, and hypercholesterolemia) had similar predictive value in the validation sample and development sample. The predicted probabilities of stenosis agreed well with the observed frequencies (Hosmer-Lemeshow goodness-of-fit test, P = 0.87). The prediction rule discriminated reasonably between patients with and without stenosis in the validation sample with an area under the receiver operating characteristic curve of 0.71. If only patients with predicted probabilities of stenosis of 5% or more were referred for renal angiography, the number of referrals was reduced by 20%, while 9% of patients with a stenosis were missed.

CONCLUSIONS

The prediction rule was valid in more recently treated patients in other settings. If used conservatively, the rule can reliably exclude a small proportion of patients from angiography.

False Aneurysm Formation Following Cutting Balloon Angioplasty in the Renal Artery of a Child

PURPOSE

To report the fortuitous discovery of a false aneurysm 7 years after cutting balloon angioplasty for severe renal artery fibromuscular dysplasia in a child.

CASE REPORT

A 3-year-old girl with neurofibromatosis was referred to our institution because of high blood pressure (220/160 mmHg). Computed tomography identified coarctation of the aorta and severe bilateral renal artery stenoses. The coarctation was successfully resected. One month later, bilateral renal artery angioplasty with a 3-mm balloon was unsatisfactory, so a second angioplasty one month later was done with a 3.25-mm cutting balloon. This procedure was complicated by a minimal arterial rupture, which resolved spontaneously after inflation of a regular balloon. Normal blood pressure was restored. The child was lost to follow-up until 7 years later, when recurrent hypertension (200 mmHg systolic) prompted referral again. Arteriography showed a very severe stenosis on the right side and a 30-mm false aneurysm of the left renal artery at the rupture site. Due to her age, the patient underwent surgery, which brought the blood pressure under control.

CONCLUSIONS

False aneurysm of the renal arteries is a rare complication of percutaneous angioplasty. In a child, the cutting balloon would appear to be contraindicated for concentric dysplastic stenoses that are resistant to regular balloon angioplasty.