Renal angioplasty: better for treating hypertension or for rescuing renal function?

Outcome following renal autotransplantation in renal artery stenosis

Introduction

With significant advances in the area of interventional radiology, angioplasty and stenting have become preferred first-line treatment in patients with significant renal artery stenosis. However, not all patients have favorable anatomy to undergo minimally invasive treatments, and reconstruction of the renal artery is an option. In select cases, either improved renal function or maintenance of existing function and sometimes resolution of hypertension can follow surgical treatment.

Material and Methods

This was a prospective observational study conducted from August 2010 to June 2016. Patients <45 years of age with uncontrolled hypertension secondary to renovascular hypertension (RVH) and refractory to medical management and renal arterial disease unfavorable for percutaneous intervention were included in the study. All patients were evaluated thoroughly using computed tomography angiography and diethylenetriaminepentaacetic acid renal scan. Patients underwent autotransplantation either into the right or left iliac fossa. Some kidneys required bench reconstruction of the renal artery and/or its branches before being implanted into either iliac fossa.

Results

Nine patients were included in the study. The mean age was 27 years. Seven were males and two were females. Five patients had bilateral renal artery stenosis. After autotransplantation, initially five patients became free of antihypertensive medicines, but on the follow-up, two patients showed rising trend of blood pressure. The evaluation revealed narrowing at anastomosis site in both patients with salvageable kidney function in one patient. Angioplasty with stenting was done in this patient while the second patient underwent secondary nephrectomy. At 2 years of follow-up, four patients required no antihypertensive medicines.

Conclusion

Autotransplantation can be a successful treatment of severe RVH and should be considered in patients with renal arterial disease unfavorable for percutaneous intervention.

Treatment of renovascular hypertension by transluminal angioplasty--13 years experience in a single centre

OBJECTIVE

The study is a follow-up on treatment of renovascular hypertension (RVH) with percutaneous transluminal renal angioplasty (PTRA).

METHODS

Patients were screened on the basis of clinical criteria of increased probability of RVH with renography and in selected cases with renal vein renin measurements. A positive work-up suggesting a functionally important renal artery stenosis led to renal angiography and PTRA if stenosis was confirmed; in 59%, an intravascular stent was inserted.

RESULTS

Outcome of treatment was classified as follows - group I: normotensive without medication; group II: with improved control of blood pressure; group III: unchanged blood pressure control. Grouping was performed immediately after treatment, at 1 month, 6 months and at the latest follow-up. One hundred-and-twenty-two patients (124 atherosclerotic and 12 fibromuscular lesions) were treated during 13 years. Immediately after PTRA the patients were grouped as follows - I: 31%, II: 59%, III: 10%. At 1 month, I: 13%, II: 72%, III: 15%; at 6 months, I: 11%, II: 74%, III: 15%, and at the latest follow-up, I: 11%, II: 78%, III: 11%. There were few significant complications, and renal function remained on average stable.

CONCLUSION

PTRA is an effective treatment of RVH in patients selected by signs of a flow-restricting stenosis. Twelve percent were normotensive after angioplasty and a further 77% had better controlled hypertension. Few complications were seen and renal function was on average unchanged as measured by serum creatinine.

Transradial Renal Artery Angioplasty and Stenting in a Patient With Leriche Syndrome

Percutaneous interventional procedures in the renal arteries are usually performed employing a femoral or brachial vascular access. In contrast, the transradial approach has been established for coronary angiography and angioplasty. We encountered a patient with Leriche syndrome who had renovascular hypertension ascribed to a severe left renal artery stenosis. To stabilize his blood pressure, we made an attempt to relieve the renal artery stenosis with Leriche syndrome by transradial renal artery angioplasty and stenting, using devices for coronary intervention. The procedure was successful without complications or residual stenosis. His hypertension improved with less antihypertensive medications. This case suggests that the radial approach might become an alternative entry site for renal artery interventions.

Treatment of atherosclerotic renal artery stenosis

The increasing prevalence of atherosclerotic renal artery stenosis (ARAS) has prompted in recent years a more aggressive treatment of this condition for reducing BP and for preserving the jeopardized renal function. Percutaneous transluminal renal angioplasty (PTRA), alone or in conjunction with stent implantation, may be useful for both these goals. However, despite the methodological improvements that make this procedure much safer than surgery, caution must be applied before PTRA is extended to all patients with ARAS. Indeed, PTRA is associated with a 23% rate of major/minor complications and with a 20% rate of restenosis, even in arteries implanted with stent. Moreover the cure rate of hypertension achievable with PTRA is, at best, around 10%, with a 40% rate of improvements. Even for rescuing the ischemic kidney, PTRA/stent implantation are not always effective; only 35% of patients with ARAS have some improvement in renal function. These data indicate that there is an urgent need of rigorous criteria for selecting among the many patients with ARAS those who may actually benefit from the dilation procedure.

Treatment of acute renal failure caused by renal artery occlusion with renal artery angioplasty

BACKGROUND

Renovascular disease is a common cause of renal impairment and hypertension, particularly in the older population. Oligoanuric acute renal failure secondary to renal artery occlusion is not well recognized; however, it is potentially reversible if identified and treated.

METHODS

Five patients presented to our institution with oligoanuric acute renal failure. Each had evidence of vascular disease, and a prerenal insult was identified. They were investigated with renal artery Doppler ultrasound or nuclear imaging before proceeding to percutaneous angioplasty and stent placement.

RESULTS

The targeted kidney had relatively well-preserved renal size, and potential viability of the renal tissue was determined by nuclear scanning with parenchymal uptake of tracer. Percutaneous angioplasty and stent placement resulted in brisk reperfusion of the kidney and an immediate diuresis with improvement of renal function, avoiding supportive dialysis after the procedure. Contrast nephrotoxicity was identified in two of the five cases.

CONCLUSION

Renal artery occlusion should be considered as a cause of oliguric acute renal failure, particularly in patients at high risk who present with a sudden deterioration of renal function, with nuclear imaging showing potentially viable renal tissue with relatively well-preserved renal size. Percutaneous revascularization should be considered in this group.

Hypertension and renovascular disease: follow-up on 100 renal vein renin samplings

The clinical value of renal vein renin sampling (RVRS) as a prognostic tool in the treatment of renovascular hypertension was evaluated. One hundred consecutive patients were included over a 4-year period of time. About half of the patients (49%) were treated interventionally by PTRA (21%), nephrectomy (20%), or vascular surgery (8%). Seven patients (15%) were cured and 15 (32%) had improved (reduction in antihypertensive medicine) after 6 months follow-up, whereas three patients (6%) were cured and 12 (26%) improved after 3-4 years follow-up. Thus, the number of patients cured or improved is comparable with the results from our department reported 20 years ago. However, in the present report, more than twice as many patients were enrolled, leading to double costs. Different indices of lateralisation of the renin generation were calculated for the use in cases of a shrunken kidney (functional share < or =15%). None of the indices clearly discriminated between the patients who did benefit from intervention, and those who did not. The only positive finding was that a peripheral renin concentration lower than 8 mlU/l predicted no effect of intervention, which might lead to the exclusion of 11% of the patients before entering the diagnostic programme. We conclude that the RVRS demands a very restrictive referral pattern if it should be of prognostic value for the blood pressure outcome after intervention. No indices of lateralised renin concentrations proved high predictive value. However, a peripheral renin concentration low in the normal range seems useful as an indicator of no benefit from intervention.

The outcome in the United States after thoracoabdominal aortic aneurysm repair, renal artery bypass, and mesenteric revascularization

OBJECTIVES

The purpose of this study was to determine outcome and identify predictors of death after thoracoabdominal aortic aneurysm (TAA) repair, renal artery bypass (RAB), and revascularization for chronic mesenteric ischemia (CMI).

PATIENTS AND METHODS

In this retrospective analysis, data were obtained from the Nationwide Inpatient Sample, a 20% all-payer stratified sample of hospitals in the United States during 1993 to 1997. Patients were identified by the presence of a diagnostic or procedure code from the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). The main outcomes we examined were death, ICD-9-CM -based complications, length of stay, hospital charges, and disposition. A multivariate model was constructed to predict death.

RESULTS

A total of 2934 patients were identified (TAA, 540; RAB, 2058; CMI, 336) in the database. The mean age was comparable (TAA, 69 +/- 9 years; RAB, 66 +/- 12 years; CMI, 66 +/- 11 years), but the breakdown between the sexes varied by procedure (male: TAA, 53%; RAB, 55%; CMI, 24%). The mortality rate (TAA, 20.3%; RAB, 7.1%; CMI, 14.7%), complication rate (TAA, 62.2%; RAB, 37.4%; CMI, 44.6%), and the percentage of patients discharged to another institution (TAA, 21.2%; RAB, 9.3%; CMI, 12.0%) were clinically significant for all procedures. The mortality rate for RAB was greater when performed concomitant with an aortic reconstruction (4.4% vs 8.3%). All three procedures were resource intensive as reflected by the median length of stay (TAA, 14 days; RAB, 9 days; CMI, 14 days) and median hospital charges (TAA, $64,493; RAB, $36,830; CMI, $47,390). The multivariate model identified several variables for each procedure that had an impact on the predicted mortality rate (TAA, 14%-76%; RAB, < 1%-46%; CMI, < 2%-87%).

CONCLUSIONS

The operative mortality rates across the United States for patients undergoing TAA repair and RAB are greater than commonly reported in the literature and mandate reexamining the treatment strategies for these complex vascular problems.

Evaluation and treatment of renal artery stenosis: impact on blood pressure and renal function

The conventional non-invasive tests to diagnose renal artery stenosis in a general hypertensive population are not accurate enough for screening purposes. Magnetic resonance angiography might become the new gold standard, with the advantages of the absence of contrast toxicity, good accuracy, and information on flow characteristics. With regard to the treatment of hypertension in patients with renal artery stenosis, intervention is advised only when blood pressure cannot be controlled by at least three antihypertensive drugs. Patency after stenting is superior to angioplasty, although its clinical benefit has not been proved. As for renal function, evidence - although from uncontrolled studies - for the preservation of renal function by intervention is accumulating, especially in those patients with bilateral stenosis or stenosis in a single functioning kidney.

How important is atheromatous renal artery stenosis as a cause of end-stage renal disease?

In recent years atheromatous renal artery stenosis has been proposed as a common and potentially preventable cause of end-stage renal disease (ESRD). Occlusive renal artery disease causes renal failure that can be reversed following successful revascularization, but this scenario is relatively rare. Nonocclusive renal artery stenosis is commonly found in association with varying degrees of renal impairment. However, recent evidence and clinical observation suggest that a cause and effect relationship is unlikely. Experimentally, split renal function studies in cases of unilateral stenosis find similar degrees of renal impairment in both kidneys. Clinically, severe renal impairment is often found in the presence of unilateral stenoses. Another nephropathic process must be going on, probably a combination of hypertensive and atheroembolic damage. It is not surprising that the two pathologies often coexist, in view of their shared causes (principally hypertension and tobacco smoking). Previous studies of the importance of renal artery stenosis in causing ESRD probably included many cases of hypertensive and atheroembolic nephropathy. Unfortunately the potential for renal revascularization to prevent ESRD has been exaggerated.

Ischemic nephropathy

Ischemic nephropathy is a major cause of chronic renal failure in people over 50 years of age. In addition, renal artery stenosis is associated with increased mortality, particularly if renal or cardiac function is compromised. The diagnosis is made both by clinical characteristics and imaging studies. At present, duplex Doppler ultrasound and magnetic resonance angiography appear to be the most promising non-invasive screening tests. Although data from controlled trials are lacking, revascularization is the mainstay of therapy for ischemic nephropathy. Advances in percutaneous interventions now allow revascularization to be offered to many patients, including those who are poor surgical candidates. The role of medical therapies (statins, angiotensin-converting enzyme inhibitors, intensive control of blood pressure) and how to best utilize revascularization (which patients and when) remain to be defined.