The current status of surgical therapy for renal artery disease

The first reports of surgically curable hypertension in the late 1930s led to enthusiasm among clinicians for removing kidneys with arterial stenosis in hypertensive patients. The development of vascular surgical techniques in the 1950s made it possible to achieve successful renal revascularization in many of these cases. However, the cause and effect relationship between a stenotic renal artery lesion and hypertension was poorly understood and many patients treated surgically had no improvement of blood pressure postoperatively. Continued experience in this field during the past two decades has significantly improved our understanding of the natural history and functional significance of renovascular disorders. Patients with renovascular hypertension can now be identified with a high degree of accuracy and successful renal revascularization is possible in most cases. Nevertheless, multiple factors must be weighed in determining whether medical or surgical therapy is more appropriate for a given patient. These include the causal relationship of renovascular disease to hypertension, the adequacy of blood pressure control with medical therapy, the natural history of untreated renovascular disease with particular regard for the risk of sustaining impaired renal function, the medical condition of the patient, the morbidity and results of surgical therapy, and the availability of other therapeutic options such as percutaneous transluminal dilatation.     

Renovascular hypertension: current concepts

Hypertension produced by renal artery occlusive disease is an important secondary form of hypertension. Clinicians commonly encounter forms of renal arterial disease of varying severity, many of which are of little hemodynamic significance when first detected. Experimental studies emphasize that transient activation of the renin-angiotensin-aldosterone system is necessary for initiation of renovascular hypertension. At some point, angiotensin II activates additional mechanisms responsible for sustained increased blood pressure including sodium retention, endothelial dysfunction, and vasoconstriction related to production of reactive oxygen species. Widespread application of agents that block the renin-angiotensin system, including angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, render many patients with unilateral renal arterial disease manageable primarily by medical means for many years. In the setting of high a priori likelihood of renovascular disease, recognizing the potential for disease progression during medical therapy and individually evaluating the risks and benefits of renal revascularization are important tasks. Recent prospective studies show limited, but real, benefit regarding blood pressure control for patients with atherosclerotic disease. Whether earlier renal revascularization offers benefits regarding improved morbidity and mortality from cardiovascular end point reduction is an important question to be addressed in multicenter, prospective, randomized trials. Our paradigm stresses the fact that patients with renovascular hypertension require intensive blood pressure control and cardiovascular risk factor intervention, both before and after revascularization. Hence, management of such patients requires close attention and periodic review regarding restenosis and progression of vascular disease.     

Long-term results of in situ and extracorporeal surgery for renovascular hypertension caused by fibrodysplasia

In this study the early and late results of surgical reconstruction for renovascular hypertension caused by fibrodysplasia are evaluated in 53 patients treated between 1962 and 1983. There were 40 female and 13 male patients. The mean blood pressure was 208/126 mm Hg before medical therapy and 171/109 mm Hg thereafter. Bilateral renal artery stenoses were present in 12 patients. In situ revascularization was used in 26 patients and extracorporeal surgery to repair branch artery lesions was performed in 27 patients. Surgical therapy reduced the blood pressure to normal levels with minimal antihypertensive medications. This effect was already apparent 6 to 12 months after operation (mean blood pressure level of 140/90 mm Hg) and it was maintained during a mean follow-up period of 8.4 years (range 1 to 20 years) (mean blood pressure level of 134/85 mm Hg). At 6 to 12 months after operation, 79% of the patients were classified as either cured or improved. At this time the results did not appear to have been influenced by the preoperative duration of hypertension, nor by manifestations of extrarenal arteriosclerosis (ERA) as found in 10 patients, or by the surgical technique applied. But at the end of the long-term follow-up period (mean 8.3 years) the beneficial response rate of 87% appeared to have been adversely influenced by the presence of preoperative ERA, since beneficial response rates were 93% for those without and 67% for those with ERA (p = 0.17). We conclude that renal revascularization is effective both early and late for the treatment of renovascular hypertension caused by fibrodysplasia and that complex renovascular obstruction can be treated effectively with extracorporeal repair.     

Treatment of renal hypertension.

There are different types of renal hypertension: hypertension due to parenchymal renal disease, renovascular hypertension, hypertension due to urological disease, hypertension of endstage renal disease. Treatment has to consider-above all-the possibility of specific, medical or surgical procedures that may cause the underlying condition. If the underlying disease is not amenable to specific therapy, symptomatic medical treatment to lower blood pressure is indicated: besides control of sodium-intake and body weight antihypertensive drugs are generally indicated. We use them, alone or in combination, in the following line of order: diuretics, beta-adrenergic blockers, dihydralazine, reserpine, clonidine, alpha-methyldopa, guanethidine.     

Surgical treatment of renovascular hypertension caused by arteriosclerosis. II. Influence of preoperative risk factors and postoperative blood pressure response on late patient survival

This study assesses the late survival of 103 patients with renovascular hypertension caused by arteriosclerosis who underwent reconstructive surgery during the period of 1959 through 1982. It provides a detailed analysis of the influence of preoperative factors and the postoperative blood pressure response to fatal and nonfatal cardiovascular events during follow-up. All patients suffered from severe hypertension. Arteriosclerosis was limited to the renal arteries in 52% of the patients, while 48% showed overt extrarenal arteriosclerosis. Hypertensive target organ damage was present in 68% of the patients. At a mean of 8.5 months postoperatively, 80% of the patients showed beneficial and 20% showed unsatisfactory blood pressure responses. These results were not related to the presence or absence of extrarenal arteriosclerosis. Overall, late (10 years) patient survival was significantly lower than the expected survival of a reference population (79% versus 92%; p less than 0.0001). Late patient survival was not influenced by the absence or presence of extrarenal arteriosclerosis (82% versus 82%) or target organ damage (83% versus 82%), but late survival was significantly better with beneficial (87%) than with unsatisfactory blood pressure responses (67%). This effect was especially conspicuous in the presence of extrarenal arteriosclerosis (88% versus 57%; p = 0.04) but not in its absence (86% versus 74%; p = 0.41). In terms of long-term survival, these findings clearly demonstrate the favorable effect of successful surgical treatment of patients with renovascular hypertension caused by arteriosclerosis. Moreover, they illustrate that the mere presence of preoperative extrarenal arteriosclerosis or target organ damage is not sufficient argument against surgical therapy.     

Surgical treatment of renovascular hypertension caused by arteriosclerosis. I. Influence of preoperative factors on blood pressure control early and late after reconstructive surgery

This study evaluates the long-term efficacy of reconstructive surgery for renovascular hypertension caused by arteriosclerosis, which was performed on 112 patients from 1959 to 1983. Despite medical therapy, all patients had persistent hypertension, with a mean preoperative blood pressure of 188/113 mm Hg. Their median age was 49 years, and the median duration of objectively documented hypertension was 21 months at the time of surgery. Manifestations of extrarenal arteriosclerosis (ERA) were present in 57 patients (51%). Results were evaluated both at a short-term (ST) interval (mean: 8.4 months) and at a long-term (LT) interval (mean: 8.9 years) postoperatively. Patients were classified by means of strict criteria as cured, improved, or unsuccessfully treated. If a patient was cured or if his condition improved, this was considered a beneficial blood pressure response. Beneficial responses were maintained during LT follow-up, since the respective percentages for cure and improvement were 24% and 50% at the ST interval and 18% and 61% at the LT interval. These results had not been influenced by either older age or the presence of ERA, since results were similar in patients older and younger than the median age and in those with and without ERA. The preoperative duration of hypertension was the only pertinent clinical feature that influenced the LT interval results, LT beneficial responses were observed in 95% of the patients with a shorter duration and in 78% of those with a longer duration of preoperative hypertension than the median (p = 0.01). We conclude that surgical therapy for renovascular hypertension caused by arteriosclerosis can effectively reduce blood pressure and that this result is maintained during LT follow-up. In terms of anticipated blood pressure response, older age, longer duration of hypertension, and the presence of ERA do not exclude surgical therapy.     

Renovascular hypertension

Renal artery stenosis is one of the most important forms of secondary hypertension. For years, the only causative treatment was nephrectomy. With rapid advances in cardiovascular and transplantation surgery, operative procedures in renovascular hypertension become more and more sophisticated. Revascularization is superior to medical management of renovascular hypertension in terms of preserved renal function. In recent years, surgical result have been excellent, and even patients with rather complex forms of renovascular hypertension have been successfully operated upon. New classes of antihypertensive drugs, particularly beta-blockers and angiotensin I converting enzyme inhibitors, have enabled the control of blood pressure in most patients with renovascular hypertension but do not assure preservation of renal function. Finally, a fascinating technique, the percutaneous transluminal renal angioplasty, has rapidly advanced to become one of the most popular methods in the treatment of hypertension secondary to renal artery stenosis. However, percutaneous transluminal renal angioplasty is the treatment of choice for most nonostial, nonocclusive lesions.     

Renovascular hypertension: treatment with the oral angiotensin-converting enzyme inhibitor enalapril

Sixteen patients with an established diagnosis of renovascular hypertension were entered in an open study of enalapril (MK421), an oral angiotensin-converting enzyme (ACE) inhibitor, for treatment of their hypertension. Initial blood pressure was 178.9 +/- 6.3/106.2 +/- 3.1 mm Hg during conventional therapy on a median of 3 different antihypertensive agents. All antihypertensive therapy was ceased and the patients admitted to hospital. Following introduction of enalapril, blood pressure fell to 161.5 +/- 6.9/90.6 +/- 4.1 mm Hg at 24 h (p less than 0.01 systolic and diastolic). Blood pressure control (diastolic blood pressure, phase V, less than 95 mm Hg) was achieved with monotherapy in 7 patients and in a further 5 patients with addition of a diuretic. Renal function was compromised in 4 patients, requiring cessation of enalapril in 2 instances. Enalapril is an oral ACE inhibitor useful in the treatment of renovascular hypertension. Close monitoring of renal function is necessary during the introduction of enalapril therapy in patients with renovascular hypertension.     

Revascularization for atherosclerotic renal artery stenosis: the treatment of choice?

Atherosclerotic renal artery stenosis (ARAS) is an important cause of renal dysfunction and secondary hypertension, and is associated with adverse cardiovascular events and increased mortality. The natural history of ARAS is characterized by anatomic disease progression and/or renal dysfunction in only a minority of patients. Medical therapy for ARAS is directed primarily toward blood pressure control and cardiovascular risk factor reduction. Renal artery revascularization is an additional treatment option for ARAS associated with ischemic nephropathy or severe, poorly controlled hypertension despite aggressive medical therapy. Unfortunately, the benefits associated with revascularization versus medical therapy alone remain unproven. Renal artery revascularization may be accomplished through open surgical revascularization or angioplasty and stenting. Although surgical renal revascularization is associated with more durable results and relatively lower risk for postoperative renal function decline, the increased risk of death or major complications associated with this management approach limit its use in patients with significant comorbidities. Renal artery angioplasty and stenting is being utilized with increasing frequency but is of uncertain benefit and is associated with rates of post-intervention renal function improvement and deterioration that are approximately equal. Renal function outcomes associated with angioplasty and stenting may be improved through a selective treatment approach and utilization of distal embolic protection. Renal artery revascularization represents the only treatment alternative for patients unresponsive to medical management, and is therefore the 'treatment of choice' in this select group. Results of ongoing randomized trials are eagerly anticipated and may provide useful guidance for future management of ARAS.     

Epidemiology and clinical presentation

Renovascular disease appears to be increasing in prevalence, particularly in older subjects with atherosclerotic disease elsewhere. Its clinical manifestations and presentation are changing because of rapid advances in medical therapy and other comorbid events. Although fibromuscular dysplasia and other diseases affecting the renal artery can produce the syndrome of renovascular hypertension, atherosclerotic renal artery stenosis is the most common clinical entity. It can produce a spectrum of manifestations, ranging from asymptomatic ("incidental"), identified during angiographic evaluation of other conditions, to progressive hypertension to accelerated cardiovascular disease with pulmonary edema and advanced renal failure. With the widespread application of drugs which block the renin-angiotensin system, including angiotensin-converting enzyme inhibitors and angiotensin antagonists, many cases of renovascular hypertension remain unsuspected and never produce adverse effects. Clinicians need to be alert to the potential for disease progression, with the potential for total renal artery occlusion and/or loss of viable renal tissue. Selection of patients for renal revascularization depends on individual balance of risks and benefits regarding the likely outcomes regarding both improvements in blood pressure control and preservation of renal function.     

Etiology and prognosis of renovascular hypertension

Eleven cases of renovascular hypertension treated by the authors during the 10-year period from 1974 to 1984 are summarized in this paper, referring particularly to its etiology and prognosis. The causative diseases included 3 cases of atherosclerosis, 4 cases of fibromuscular dysplasia, 1 case of aortitis syndrome, 1 case of abdominal aneurysm, 1 case of renovascular thrombosis, and 1 case of unknown origin. Operations were given in 10 of the 11 cases i.e., 7 cases of nephrectomy and 3 cases of reconstructive surgery for renal blood-flow. The results of operations at discharge were 7 cases of blood pressure normalization, 2 cases of its improvement and 1 case of no change. There was no operative mortality. The outcome of long followup revealed that 2 of the 3 patients with atherosclerosis died in 9 months and 1 year and 10 months, respectively, due to cerebral hemorrhage and renal failure. However, the patients with other diseases maintained their health for 5 years and 5 months (mean observation period), with normal blood pressure or a mild hypertension. Sometimes, in patients with atherosclerosis in whom severe arteriosclerotic lesions already exist in the cardiovascular system, conservative therapy is better than surgical therapy. The indication for surgical therapy, should be made after considering the results of the angiotensin II analogue test.     

Treatment of renovascular hypertension by unilateral nephrectomy. A follow-up study in patients above 60 years of age

The long term results of surgical intervention in 26 elderly patients with renovascular hypertension are presented. All patients were above 60 years of age at the day of operation. The majority of the patients had atherosclerotic renovascular disease with only one case of fibromuscular dysplasia. Several patients had severe extrarenal atherosclerotic disease. The diagnosis of renovascular hypertension was based upon the results of isotope renography, renal arteriography and renal vein catheterization. All patients underwent unilateral nephrectomy. Notably, no deaths or complications occurred in relation to surgery. At the follow-up study, blood pressure was lowered and the requirement for antihypertensive drugs reduced in 86% of the patients. We conclude that unilateral nephrectomy in elderly high risk patients with renovascular hypertension is a safe and efficient procedure.     

Leitlinie zur chirurgischen Therapie bei Erkrankungen der Nierenarterien

Background

These guidelines are the current publication of the German guidelines for surgical revascularization of renal artery disease, focusing on atherosclerotic renal artery stenosis. These guidelines update a previous version: Allenberg JR (1998) Guidelines for renovascular disease. In: German College of Vascular Surgery (DGG) Guidelines for diagnostic and therapy in vascular surgery. Deutscher Ärzteverlag, Köln

Purpose

The aim was to evaluate the effect of surgical revascularization on clinical outcomes in adults with atherosclerotic renal artery stenosis in comparison to endovascular therapy or best medical treatment.

Data Sources

The appropriate criteria were reviewed by a literature search (MEDLINE database) and updated in order to evaluate the results of previous studies and obtain new and highly significant scientific evidence on the surgical therapy of renovascular diseases.

Data interpretation

Using the evidence-based criteria there were only two randomized trials with an evidence level type Ib, one comparing surgical revascularization with best medical treatment and another comparing surgical revascularization with percutaneous transluminal angioplasty (PTA). In both studies there were no significant differences in the outcome. However, the statistical power of these trials with a total of 110 randomized patients was poor. Many trials with evidence level II and III have been carried out. Available evidence is not sufficient to predict which intervention would result in better outcomes. There have been no randomized prospective trials comparing the three therapeutic options, surgical revascularization, PTA/stent and best medical treatment.

Conclusion

An advantage for a specific type of therapy has not yet been demonstrated. The decision for any kind of treatment approach depends on the individual renal artery lesion, the therapeutic options, skills and the necessary interdisciplinary infrastructure of the treating medical unit.     

Evidence-based medicine in renal artery stenting

Atherosclerotic renovascular disease is an increasingly recognized cause of severe hypertension and declining kidney function. Patients with atherosclerotic renovascular disease have been demonstrated to have an increased risk of adverse cardiovascular events. Over the course of the last two decades renal artery revascularization for treatment of atherosclerotic renal artery stenosis (RAS) has gained great increase via percutaneous techniques. However the efficacy of contemporary revascularization therapies in the treatment of renal artery stenosis is unproven and controversial. The indication for renal artery stenting is widely questioned due to a not yet proven benefit of renal revascularization compared to best medical therapy. Many authors question the efficacy of percutaneous renal revascularization on clinical outcome parameters, such as preservation of renal function and blood pressure control. None of the so far published randomized controlled trials could prove a beneficial outcome of RAS revascularization compared with medical management. Currently accepted indications for revascularization are significant RAS with progressive or acute deterioration of renal function and/or severe uncontrollable hypertension, renal function decline with the use of agents blocking the renin-angiotensin system and recurrent flash pulmonary edema. The key point for success is the correct selection of the patient. This article summarizes the background and the limitations of the so far published and still ongoing controlled trials.     

Surgical treatment of complete renal artery occlusion in pediatric patients

Two children, 8 and 11 years old, presented with severe hypertension secondary to unilateral and bilateral total occlusion of the renal arteries, respectively. The 11-year-old developed sudden anuria requiring hemodialysis. Successful surgical reconstruction allowed recovery of renal function and normal blood pressure in both patients. Routine blood pressure control in the pediatric patient population, high clinical awareness, and judicious use of arteriography, provide the best chance for early diagnosis of renovascular disease. Surgical revascularization or transluminal angioplasty are the treatment modalities of choice in appropriately selected cases of renal artery stenosis. When total occlusion occurs, retrieval or preservation of renal function can be successfully achieved by direct surgical intervention.     

Long-term follow-up of neonatal renovascular hypertension

Twelve neonates with hypertension have been followed for a mean of 5.75 years. At onset of hypertension, mean peak blood pressure was 159/99 mmHg. Ten infants had umbilical artery catheters, 9 placed above the origin of the renal arteries. Radionuclide renal scan, and/or angiography demonstrated renovascular disease, primarily renal artery thrombosis, in 11 infants. Onethird of infants were asymptomatic, one-third had normal urinalyses and two-thirds had elevated peripheral plasma renin activities. Blood pressure normalized with medical therapy in all infants and remained normal when therapy was discontinued. Ten infants have normal creatinine clearances on follow-up but 5/11 have unilateral renal atrophy. Radionuclide scans have remained abnormal, even in infants without renal atrophy. In summary, neonatal renovascular hypertension is frequently secondary to renal artery thrombosis, associated with umbilical artery catheterization. Blood pressure usually normalizes with conservative medical management and remains normal off medications. Persistent abnormalities in renal size and function are common.     

Renovascular hypertension and Takayasu's disease

A total of 18 patients underwent surgical correction of renal hypertension secondary to Takayasu's disease after unsuccessful maximum medical therapy. Although the patients required an extensive surgical procedure, the morbidity and mortality rates were low (1 perioperative death in 18 patients). Followup showed that 67 per cent of the patients were cured of the hypertension and 28 per cent were improved. The results appear as good as those seen in the treatment of renovascular hypertension owing to fibromuscular disease or atherosclerosis.     

Therapeutic guide for renovascular hypertension with reevaluation of surgical treatment

Therapeutic guide for renovascular hypertension has been greatly changed by a development of beta-blockers and captopril, and an introduction of percutaneous transluminal angioplasty (PTA) The accepted opinion was that surgical therapy was superior to drug therapy since Hunt & Strong reported the follow-up results in 1973. However, efficacy of drug therapy was reevaluated by an appearance of beta-blockers and captopril and the number of patients applied to operation was decreased. Further, since PTA was widely used in clinical practice from the end of 1970s, surgical therapy for renovascular hypertension was hardly or never considered. Has the necessity of surgical therapy really ceased to exist? Recently, we encountered 2 cases of bilateral renovascular hypertension and reevaluated the necessity of surgical therapy during the course of treatment. The first case was in a 43-year-old male, for whose bilateral renovascular stenosis a bilateral PTA was applied. One year later a complete occlusion of the right renal artery and re-stenosis of the left renal artery developed. Thus, removal of the right kidney and the auto-transplantation of the left kidney were conducted. The second case was in a 17-year-old female with bilateral renovascular stenosis complicated by moya-moya disease. PTA was conducted for the left kidney with shorter range of stenosis and auto-transplantation was conducted for the right kidney with longer range of stenosis. The prognosis was favorable in both cases and hypertension was cured or improved. We recognized and re-evaluated the necessity of surgical therapy for patients who were unsuccessful to PTA or patients with bilateral renovascular hypertension from our experience and literatures.(ABSTRACT TRUNCATED AT 250 WORDS)     

Renovascular hypertension. 8 years experience of a vascular surgery centre

AIM: The aim of this study was to evaluate the technical success and clinical outcome of surgical revascularization, angioplasty and/or stenting for renal artery stenosis (RAS) in patients with renovascular hypertension (RVH). The secondary aim was to identify independent negative predictors of blood pressure control after successful renal revascularization. METHODS: From January 1998 to July 2006, we treated 97 cases of RAS in 83 RVH patients. Inclusion criteria were RAS > or =80% associated with hypertension refractory to medical control with at least three drugs including a diuretic. Therapeutic options were surgical revascularization in 15 cases (11 renal endarterectomies, 4 aortorenal bypasses) and endoluminal treatment in 82 (14 balloon angioplasties, 68 stents). RESULTS: Technical success was 100% for both surgical and endovascular procedures; 13 cases of restenosis (> or =80%) were detected: 12 (14.6%) in the endoluminal group and one (6.6%) in the surgical group (P=0.68). During the follow-up period (average 37 months, range 6-94), blood pressure control improved in 43% of patients, disease stabilized in 37% and the natural course of RVH deteriorated in 20%. Multivariate Cox regression analysis showed that only a long history of antihypertensive drug use was a predictor of inefficacy of blood pressure control after revascularization (P<0.04). CONCLUSION: The complete resolution of RVH associated with severe RAS appears unrealistic in several cases. Early and long-term results in terms of technical success and restenosis were acceptable and similar for surgical and endovascular renal intervention. An early diagnosis of RVH could improve the control of hypertension after successful renal revascularization.     

Continuing uncertainty about the value of percutaneous revascularization in atherosclerotic renovascular disease: a meta-analysis of randomized trials.

BACKGROUND:To study the effect of revascularization on blood pressure (BP) and serum creatinine (SCr) in patients with atherosclerotic renovascular disease (ARVD). METHODS:Three randomized studies comparing balloon angioplasty (plus medication if necessary) with medical therapy alone in patients with ARVD were identified. In one study, patients were stratified and analysed according to whether they had unilateral or bilateral disease. Therefore, four sets of results were available for inclusion in a meta-analysis comparing BP and SCr at 6 months and changes from baseline. RESULTS:The three trials recruited 210 patients. There was no clear benefit for angioplasty when comparing BP at 6 months. Relative to the medical therapy group, the mean (95% CI) systolic/diastolic BP was 2.9 mmHg (-9.1, 3.4)/0.35 mmHg (-3.6, 2.9) lower in the angioplasty group (P=0.4/0.8). There was, however, some suggestion of benefit for angioplasty when changes in BP were compared. There was a greater reduction in the systolic/diastolic BP in the angioplasty group, with a difference of 6.3 mmHg (-11.7, -0.8)/3.3 mmHg (-6.2, -0.4) in the mean change (P=0.02/0.03). There was some suggestion of benefit for angioplasty in terms of changes in SCr, although this was not significant (P=0.06). CONCLUSIONS:The reported trials have been too small to determine reliably the role of angioplasty in ARVD. Although the combined results of three previous trials exclude the possibility of a large improvement in renal function or hypertension after angioplasty, a moderate but clinically worthwhile benefit cannot be ruled out. Further large-scale randomized evidence is needed.