Predictive Factors and Therapeutic Approach of Renovascular Disease: Four Years’ Follow-Up

How should we define appropriate patients for percutaneous transluminal renal angioplasty treatment?

Renovascular hypertension (RVH) is one of the most common causes of secondary hypertension and can result in resistant hypertension. RVH is associated with an increased risk for progressive decline in renal function, cardiac destabilization syndromes including "flash" pulmonary edema, recurrent congestive heart failure, and cerebrocardiovascular disease. The most common cause of renal artery stenosis (RAS) is atherosclerotic lesions, followed by fibromuscular dysplasia. The endovascular technique of percutaneous transluminal renal angioplasty (PTRA) with or without stenting is one of the standard treatments for RAS. Randomized controlled trials comparing medical therapy with PTRA to medical therapy alone have failed to show a benefit of PTRA; however, the subjects of these randomized clinical trials were limited to atherosclerotic RAS patients, and patients with the most severe RAS, who would be more likely to benefit from PTRA, might not have been enrolled in these trials. This review compares international guidelines related to PTRA, reevaluates the effects of PTRA treatment on blood pressure and renal and cardiac function, discusses strategies for the management of RVH patients, and identifies factors that may predict which patients are most likely to benefit from PTRA.

Renal artery stenosis presenting as preeclampsia

Background

Renal artery stenosis is a notorious cause of secondary hypertension which classically presents as chronic refractory hypertension, recurrent flash pulmonary edema or renal insufficiency after initiation of an angiotensin converting enzyme inhibitor. Rarely, there have been reported cases of pregnant patients presenting with new onset or superimposed preeclampsia secondary to renovascular hypertension. In this subset of patients, renovascular hypertension carries significantly higher risks including obstetric, fetal and medical emergencies and death. Prompt treatment is required. However, the teratogenic risks of radiological investigations and antihypertensive medications limit diagnostic and management options thus posing quite a dilemma.

Case presentation

A 38-year-old female, at 33 weeks of gestation, was hospitalized for preeclampsia with severe features. A viable neonate had been expeditiously delivered yet the patient’s post-partum blood pressures remained severely elevated despite multi-class anti-hypertensive therapy. Renal artery dopplers revealed greater than 60% stenosis of the proximal left renal artery and at least 60% stenosis of the right renal artery. Renal angiography showed 50% stenosis of the left proximal renal artery for which balloon angioplasty and stenting was performed. The right renal artery demonstrated less than 50% stenosis with an insignificant hemodynamic gradient, thus was not stented. Following revascularization, the patient’s blood pressure improved within 48 h, on dual oral antihypertensive therapy.

Conclusions

Preeclampsia that is refractory to multi-drug antihypertensive therapy should raise suspicion for renal artery stenosis. Suspected patients can be screened safely with Doppler ultrasonography which can be then followed by angiography. Even if renal artery stenosis does not seem severe, early renal revascularization may be considered in patients with severe preeclampsia who do not respond to antihypertensive management.

Current Concepts in the Treatment of Renovascular Hypertension

Renovascular disease (RVD) remains a major cause of secondary and treatment-resistant hypertension. Most cases are related either to fibromuscular or atherosclerotic lesions, but a variety of other causes including arterial dissection, stent occlusion, and embolic disease can produce the same syndrome. Recent studies emphasize the kidney's tolerance to moderate flow reduction during antihypertensive drug therapy and the relative safety of medical therapy to control blood pressure. Several prospective trials in moderate RVD fail to identify major benefits from endovascular revascularization for moderate atherosclerotic disease. However, high-risk and progressive renovascular syndromes are recognized to be relatively refractory to medical therapy only and respond better to combining renal revascularization with ongoing medical therapy. Clinicians caring for complex hypertension should be familiar with pathogenic pathways, imaging techniques, and a rational approach to managing renovascular hypertension in the current era.

Treatment of hypertension in patients with atherosclerotic renal artery stenosis, updated

Atherosclerotic renal artery stenosis (ARAS) is a fairly common disease of elderly patients and is discovered incidentally in 6.3% to 38% in those undergoing diagnostic cardiac or abdominal angiography. Of those patients diagnosed with renal artery stenosis, in 90% it is due to ARAS and in 10% to fibromuscular dysplasia (FMD), which is a disease of younger persons, mostly females. Renal artery stenosis is frequently associated with hypertension and impaired renal function, and it is perceived by many physicians as the primary cause of hypertension and renal failure. For this reason, they believe that hypertension and renal failure can be significantly improved by performing percutaneous transluminal renal angioplasty (PTRA) with a stent placement as the preferred treatment instead of medical therapy. This practice has led to an increase in angioplasties, especially by interventional cardiologists who are familiar with the procedure. However, the results of several randomized studies comparing interventional therapy with medical therapy have shown no significant difference between the 2 treatment modalities in blood pressure reduction and prevention and in worsening of renal function. Similar results have been found by nonrandomized trials in patients treated selectively with PTRA. For this review, a Medline search was conducted of the English-language literature from January 1, 2006 to December 31, 2013, using the terms atherosclerotic renal artery stenosis and renal artery stenosis; 6 pertinent randomized studies were selected. These studies, with collateral literature, are discussed in this review. The data show that PTRA with stent plus medical therapy in patients with ARAS is not superior to medical therapy alone in lowering the blood pressure, in preventing renal function deterioration, and in reducing all-cause mortality, cardiovascular morbidity or mortality, and strokes.

Balloon angioplasty, with and without stenting, versus medical therapy for hypertensive patients with renal artery stenosis

BACKGROUND

Atherosclerotic renal artery stenosis is the most common cause of secondary hypertension. Balloon angioplasty with stenting is widely used for the treatment of hypertensive patients with renal artery stenosis but the effectiveness of this procedure in treating hypertension, improving renal function and preventing adverse cardiovascular and renal events remains uncertain. This is an update, to include the results of recent, important large trials, of a review first published in 2003.

OBJECTIVES

To compare the effectiveness of balloon angioplasty (with and without stenting) with medical therapy for the treatment of atherosclerotic renal artery stenosis in patients with hypertension. The following outcomes were compared: blood pressure control, renal function, frequency of cardiovascular and renal adverse events, presence or absence of restenosis of the renal artery, side effects of medical therapy, numbers and defined daily doses of antihypertensive drugs.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched May 2014) and CENTRAL (2014, Issue 4). Bibliographies were also reviewed and trial authors were contacted for more information.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing balloon angioplasty with medical therapy in hypertensive patients with haemodynamically significant renal artery stenosis (greater than 50% reduction in luminal diameter) and with a minimum follow-up of six months.

DATA COLLECTION AND ANALYSIS

Data were extracted independently on trial design, participants, interventions and outcome measures. A formal meta-analysis was completed to assess the effect on blood pressure, renal function and cardiovascular and renal adverse events. Peto's odds ratios (ORs) and corresponding 95% confidence intervals (CI) for dichotomous outcomes and mean differences (MD) and corresponding 95% CIs for continuous variables were calculated.

MAIN RESULTS

Eight RCTs involving 2222 participants with renal artery stenosis were included in the review. The overall quality of evidence included in this review was moderate. Limited pooling of results was possible due to the variable presentation of some of the trial outcomes. Meta-analysis of the four studies reporting change in diastolic blood pressure (BP) found a small improvement in diastolic BP in the angioplasty group (MD -2.00 mmHg; 95% CI -3.72 to -0.27) whilst the meta-analysis of the five studies reporting change in systolic BP did not find any evidence of significant improvement (MD -1.07 mmHg; 95% CI -3.45 to 1.30). There was no significant effect on renal function as measured by serum creatinine (MD -7.99 µmol/L; 95% CI -22.6 to 6.62). Meta-analysis of the three studies that reported the mean number of antihypertensive drugs found a small decrease in antihypertensive drug requirements for the angioplasty group (MD -0.18; 95% CI -0.34 to -0.03). Repeat angiography was only performed on a small number of participants in a single trial and it was therefore not possible to comment on restenosis of the renal artery following balloon angioplasty. Based on the results of the seven studies that reported cardiovascular and renal clinical outcomes there were no differences in cardiovascular (OR 0.91; 95% CI 0.75 to 1.11) or renal adverse events (OR 1.02; 95% CI 0.75 to 1.38) between the angioplasty and medical treatment groups. A small number of procedural complications of balloon angioplasty were reported (haematoma at the site of catheter insertion (6.5%), femoral artery pseudoaneurysm (0.7%), renal artery or kidney perforation or dissection (2.5%) as well as peri-procedural deaths (0.4%)). No side effects of medical therapy were reported.

AUTHORS' CONCLUSIONS

The available data are insufficient to conclude that revascularisation in the form of balloon angioplasty, with or without stenting, is superior to medical therapy for the treatment of atherosclerotic renal artery stenosis in patients with hypertension. However, balloon angioplasty results in a small improvement in diastolic blood pressure and a small reduction in antihypertensive drug requirements. Balloon angioplasty appears safe and results in similar numbers of cardiovascular and renal adverse events to medical therapy.

The current status of angioplasty of atherosclerotic renal artery stenosis for the treatment of hypertension

Atherosclerotic renal artery stenosis, a fairly common disease of older persons, is a manifestation of generalized atherosclerosis, and is often associated with coronary artery disease. It is frequently associated with hypertension and impaired renal function, and is perceived by many physicians to be the cause of hypertension and renal failure. For this reason, they believe that hypertension can be cured by performing percutaneous renal artery angioplasty (PTRA) with stent placement. This practice has led to an increase in angioplasties, especially by interventional cardiologists, although the results from several randomized studies comparing interventional therapy with medical therapy have shown no significant difference between the two treatment modalities in blood pressure reduction or change in renal function. Similar results have been found by nonrandomized trials with selective PTRA. For this review, a Medline search of the English literature was conducted from 2006 to 2012, and 13 pertinent studies were selected. These studies with collateral literature will be discussed in this concise review.

The prevalence and meaning of eosinophilia in renal diseases on a nephrology consultation service

BACKGROUND

In recent years, we have come to understand that the eosinophil is more than the end point in clearance of parasitic infection or a maladaptive response to asthma and allergic reactions. Since eosinophilia has been reported to be common in renal diseases, we thought that an evaluation of the associations of eosinophilia on a renal consultation service would add some value to the understanding of their role in renal disease.

METHODS

This was a prospective cross-sectional study of 1339 consecutive patients referred to the nephrology service after hospitalization who were evaluated for the relationship of the amount of serum eosinophils to their diagnosis, gender, age and the presence of autoimmune disease, cancer, infection, liver disease, pleural effusions, allergies and use of prednisone, beta-blockers or beta agonists, in addition to the total white blood count, urine protein, serum concentration creatinine and phosphorus levels and estimated glomerular filtration rate.

RESULTS

The presence of vascular disease correlated the most strongly with increased eosinophil count (partial correlation coefficient, r = 0.18, P = 0.006), followed by pleural effusions (r = 0.17, P = 0.001), while total white cell count (r = -0.18, P = 0.008) and administration of beta-blockers (r = -0.13, P = 0.047) demonstrated significant inverse correlations and the presence of autoimmune disease, cancer, allergies, proteinuria and serum phosphorus concentration demonstrated no significant correlation.

CONCLUSION

There are multiple associations with increased eosinophil counts in patients seen on a nephrology consultant service; however, their presence appears less often in association with allergies or uremia and more often with vascular disease.

Primary stenting for atherosclerotic renal artery stenosis

INTRODUCTION

Endovascular treatment for atherosclerotic renal artery stenosis (ARAS) was first performed >30 years ago and its use has increased rapidly since then. However, only recently have large randomized trials rigorously evaluated its clinical benefit.

METHODS

We systematically reviewed the controlled studies on primary stenting for atherosclerotic renal artery stenosis. Studies were included if they compared the outcome of stenting with other treatments, or the outcome associated with different stent characteristics or stenting methods.

RESULTS

Stenting is preferred over angioplasty alone and over surgery when revascularization is indicated for ostial ARAS, except in cases of coexistent aortic disease indicating surgery. Randomized controlled trials showed no significant benefit and substantial risk of renal artery stenting over medication alone in patients with atherosclerotic ARAS without a compelling indication. Improvements in the procedure, such as with distal embolic protection devices and coated stents, are not associated with better clinical outcomes after stent placement for ARAS.

CONCLUSION

Recent evidence shows that impaired renal function associated with ARAS is more stable over time than previously observed. Optimal medical treatment should be the preferred option for most patients with ARAS. Only low-level evidence supports compelling indications for revascularization in ARAS, including rapidly progressive hypertension or renal failure and flash pulmonary edema.