Surgery of the renal arteries

Hypertension is a pervasive disease affecting between 10% and 15% of the population. Hypertension is manifested silently by an accelerated rate of atherosclerosis leading to increased incidence of cardiovascular, cerebrovascular, and peripheral vascular morbidities and deaths. Through activation of the renin-angiotensin axis, renovascular disease (RVD) accounts for approximately 5% of this hypertensive population. Recently, the relationship between renovascular occlusive disease and progressive renal insufficiency has been delineated and termed ischemic nephropathy. Patients with ischemic nephropathy present with hypertension in conjunction with elevated serum creatinine. It has been estimated that 15% of patients initiating dialysis each year have renovascular disease as the origin of their renal dysfunction. Renal dysfunction is due to a global reduction in renal perfusion, most often as a result of bilateral renal artery occlusive disease, although a mild form of renal insufficiency can be brought on by unilateral occlusive disease due to the effects of the renin-angiotensin system on the contralateral kidney. Historically, treatment of RVD has been centered on interrupting the renin-angiotensin axis and curing the resultant hypertension and its associated morbid disease. Currently, repair efficacy has been realized with concurrent retrieval of excretory renal function and cure of renovascular hypertension.      

Abdominal aortic coarctation inducing aortic occlusion and renovascular hypertension.

Abdominal aortic coarctation is a rare, non-atherosclerotic disease. It is a functionally significant at an early age when associated with aortic branch stenosis and renovascular hypertension. The pathogenesis of aortic constrictive lesions remains unknown, but may be related to developmental error or aortic growth arrest and various hypotheses have been reported. When the renal arteries are involved by the coarctation, severe hypertension is common at an early age and in untreated patients, life-threatening complications commonly occur. Patients who reach the age of 40 years generally have the coarctation below the renal arteries but even when the renal arteries are not involved by the coarctation, renovascular disease may still occur due to secondary atherosclerosis. Aortic thrombosis secondary to abdominal aortic coarctation with renovascular disease and lower limb ischemia, occurring in a 63-year old woman, is reported.     

Renal artery stenosis and chronic ischemic nephropathy: epidemiology and diagnosis

Atherosclerotic renal artery stenosis (RAS) is the most common primary disease of the renal arteries and results in renovascular hypertension and ischemic nephropathy. Ischemic nephropathy from atherosclerotic RAS is increasingly recognized as a cause of chronic kidney disease (CKD) and in severe cases can lead to end-stage renal disease. The exact prevalence of atherosclerotic RAS is unknown because the disease is often asymptomatic and few are screened unless they have significant traditional cardiac risk factors or symptoms. A high prevalence of atherosclerotic RAS is seen in patients with advanced age, congestive heart failure, and extrarenal atherosclerosis. The primary reason for diagnosing ischemic nephropathy from renovascular disease is that the loss of kidney function is potentially reversible through treatment of the occlusion with surgical revascularization or percutaneous transluminal renal angioplasty. However, the benefits of revascularization have to be considered in the context of other comorbid disease and remain controversial. There are several tests available for the screening and diagnosis of atherosclerotic RAS; however, the diagnostic test of choice should be based on patient factors and institutional expertise because the best test is the one performed most often at the individual medical facility.     

Renal artery dissection.

Renal artery dissections are stenotic or occlusive lesions most often observed in hypertensive patients with underlying atherosclerosis or fibromuscular disease. Acute dissections may present spontaneously, as a complication of diagnostic or therapeutic angiography or as an agonal event associated with overwhelming systemic illness. Chronic dissections may produce renovascular hypertension or be entirely asymptomatic. Fourteen renal artery dissections have been encountered in nine patients treated at Vanderbilt University Medical Center during the past decade. Eleven dissections have been found in seven patients with renovascular hypertension. Seven of these dissections were chronic (six functional, one silent) and four acute (two spontaneous, two secondary to angiography). Three agonal dissections were found in two additional patients postmortem: one at autopsy and bilateral dissections found at the time of cadaveric donor nephrectomy. Ten bypass procedures, including five complex branch reconstructions of which three were performed ex vivo, have been performed with 100% immediate patency and maintenance or improvement of renal function. Long-term follow-up of these patients has shown sustained patency of the reconstructed renal arteries, excellent blood pressure control, and normal renal function in all. Nephrectomy has not been required and there have been no associated deaths. Seventy-seven additional renal artery dissections in 72 patients collected from previous reports have been analyzed. Patient survival (55/72, 76.4%) and preservation of the involved kidney in surviving patients (26/55, 47.3%) were low in these earlier series. In addition, renal failure was associated with 59% of the deaths. The lethality of renal artery dissections and the ease and success of revascularization, which preserves renal function and ameliorates associated renovascular hypertension, emphasize the need for an aggressive approach to the recognition and treatment of this entity. Therapy should be directed toward arterial reconstructions and the preservation of functioning renal tissue.     

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.     

Renal duplex sonography: evaluation of clinical utility

With the exception of conventional angiography, no previously proposed screening test has the necessary sensitivity/specificity to guide further evaluation for correctable renovascular disease. Recently, renal duplex sonography has been suggested as a useful substitute in such screening for renovascular disease. This report analyzes our data collected over the past 10 months in evaluation of renal duplex sonography to examine its diagnostic value. The study population for renal duplex sonography validity analysis consisted of 74 consecutive patients who had 77 comparative renal duplex sonography and standard angiographic studies of the arterial anatomy to 148 kidneys. Renal duplex sonography results from six kidneys (4%) were considered inadequate for interpretation. This study population contained 26 patients (35%) with severe renal insufficiency (mean 3.6 mg/dl) and 67 hypertension (91%). Fourteen patients (19%) had 20 kidneys with multiple renal arteries. Bilateral disease was present in 22 of the 44 patients with significant renovascular disease. Renal duplex sonography correctly identified the presence of renovascular disease in 41 of 44 patients with angiographically proven lesions, and renovascular disease was not identified in any patient free of disease. When single renal arteries were present (122 kidneys), renal duplex sonography provided 93% sensitivity, 98% specificity, 98% positive predictive value, 94% negative predictive value, and an overall accuracy of 96%. These results were adversely affected when kidneys with multiple (polar) renal arteries were examined. Although the end diastolic ratio was inversely correlated with serum creatinine (r = -0.3073, p = 0.009), low end diastolic ratio in 35 patients submitted to renovascular reconstruction did not preclude beneficial blood pressure or renal function response. We conclude from this analysis that renal duplex sonography can be a valuable screening test in the search for correctable renovascular disease causing global renal ischemia and secondary renal insufficiency (ischemic nephropathy). Renal duplex sonography does not, however, exclude polar vessel renovascular disease causing hypertension alone nor does it predict hypertension or renal function response after correction of renovascular disease.     

Evaluation and preparation for surgical treatment of renal artery disease

The diagnosis of renovascular disease and renovascular hypertension is outlined. A comparison and analysis of the advantages of three forms of treatment are made. These include medical management, percutaneous transluminal coronary angioplasty, and surgical intervention. Selection of patients for revascularization to preserve renal function is discussed, and guidelines for determining renal salvageability are presented. Surgical revascularization is the treatment of choice for patients with ostial atherosclerotic renal artery disease, branch renal artery disease, or a renal artery aneurysm.     

Kidney diseases and hypertension

Renal disease has been recognized as both a cause and a consequence of hypertension. Renal hypertension may be of vascular and nonvascular origin. Generally, the prevalence of hypertension increases with decreasing renal function, including more than 90% of patients with terminal renal failure. However, hypertension is more often found in glomerular than in interstitial disease. The pathomechanisms operative in renal hypertension are sodium retention with concomitant volume expansion, an increase in plasma renin activity or a combination of both factors. While mechanical intervention is usually tried in renovascular hypertension and in the rare cases with "urological" causes, no causal therapy is possible in most cases of renoparenchymal disease. However, as the normalization of blood pressure is the best proved way to stop or at least retard the progression of renoparenchymal disease, pharmacological intervention is mandatory even if the medication sometimes has side effects.     

Therapeutic experience in renal hypertension: response treatment in 47 cases.

We report our experience in the treatment of 47 cases of renal hypertension patients with renovascular hypertension or hypertensive reno-parenchymal disease surgical therapy is essential and non-surgical therapy has its limitations. The necessity for an operation can be based on the determination of bilateral renal vein plasma renin values. Blood should be drawn from both renal veins in patients in an upright position. Surgical treatment usually produces excellent results in patients in whom renin activity on the side of the lesion is more than normal and more than 2 times that on the uninvolved side. It is advisable to perform an operation within 4 years of the onset of renal hypertension. Complete surgical cure of renal hypertension is accomplished more frequently in patients with fibromuscular dysplasia than in those atherosclerosis. The therapeutic effect of an operation in correcting hypertension is virtually the same, regardless of whether the arterial stenotic lesions are in the main renal artery or in the intrarenal arterial branches. We have found nephrectomy or dacron bypass graft to be the surgical procedure of choice in renovascular hypertension cases.     

Is incidental renal arteriography justified in a population of patients with symptomatic peripheral arterial disease?

Renal artery stenosis is a consequence of generalized atherosclerosis and many specialists perform routine selective renal angiography to detect and treat renal artery stenosis. The incidence of clinically important renal artery stenosis is not well defined in patients with symptomatic peripheral arterial disease. The purpose of this study was to better delineate the incidence of and the risk factors associated with renal artery stenosis, renovascular hypertension, and ischemic nephropathy incidentally discovered during angiography for symptomatic peripheral arterial disease. Two hundred consecutive patients undergoing angiographic evaluation of symptomatic lower extremity peripheral arterial disease were studied retrospectively. Angiograms were reviewed for the presence of renal artery stenosis (defined as >or= 25% diameter reduction in either renal artery) and findings were then correlated to the clinical diagnosis of renovascular hypertension (> 50% renal artery stenosis and >or= 3-drug resistive hypertension) and ischemic nephropathy (defined as > 50% bilateral renal artery stenosis, 3-drug hypertension, and creatinine >or= 1.5). Angiographic findings were also correlated with risk factors to determine if a relationship correlated to the presence of and degree of renal artery stenosis. Data were analyzed using the Student's t test, Chi-square model, and multiple logistic regression analysis. The overall incidence of any degree of renal artery stenosis in this study population was 26% (52 patients). Only 24 (12%) patients had an incidental finding of >or= 50% stenosis in either renal artery. Six (3%) of these patients were found to have associated renovascular hypertension. Additionally, 9 (4.5%) patients had coexistent renal insufficiency and significant renal artery stenosis; five with end-stage renal disease on chronic hemodialysis. Only one patient with end-stage renal disease had poorly controlled 3-drug hypertension. Thus definitive ischemic nephropathy was present in only one (0.5%) patient. Statistically significant risk factors associated with the presence of renal artery stenosis include hypertension (P < .001), coronary disease (P = .024), female gender (P = .010), diabetes (P = .039), aorto-iliac disease (P = .031), multiple levels of peripheral arterial disease (P < .001), and age over 60 ( P < .001). While the incidence of renal artery stenosis in patients being evaluated for symptomatic peripheral arterial disease is similar to that reported in the cardiology literature, the incidence of renovascular hypertension and ischemic nephropathy is exceedingly low (3% and 0.5%, respectively)-findings similar to data reported in the general hypertensive population. These data suggest that incidental selective renal angiography is not justified in patients with symptomatic peripheral arterial disease.     

The role of unilateral nephrectomy in the treatment of nephrogenic hypertension in children

OBJECTIVES: To define the efficacy of unilateral nephrectomy in a large series of patients presenting with renal disease and hypertension, as the latter may be a prominent finding in children with nephrourological disease (renal parenchymal disease, renovascular disease, obstruction, renal dysplasia and cancer). PATIENTS AND METHODS: We retrospectively reviewed the hospital and outpatient records of 118 children who presented for evaluation with hypertension, and who had a nephrectomy between 1968 and 2003. Patients included in the study were those who had a unilateral nephrectomy for benign renal hypertension with a normal contralateral kidney; in all, 21 had complete records and follow-up were evaluated. The hypertension was associated with primary renal disease, obstruction and renovascular disease. Blood pressure and medication requirements were compared before and after surgery, the blood pressure values also being compared with published nomograms. RESULTS: Patients were diagnosed with hypertension at a median age of 5 years and had a nephrectomy at a median of 11 months after the diagnosis. The median follow-up after surgery was 39 months. Most patients responded well and became normotensive, or there was a reduction in the need for medication. The median time to normalization was 2, 10 and 11 days in patients with primary renal disease, obstruction and renovascular disease, respectively. CONCLUSION: Nephrectomy is successful in normalizing blood pressure in children with benign renal hypertension and with a normal contralateral kidney.     

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.     

Angiotensin-converting enzyme inhibitor-induced renal failure: causes, consequences, and diagnostic uses

Angiotensin-converting enzyme inhibitor-induced renal failure is now a well-recognized phenomenon that appears to occur almost exclusively in patients with a preexisting reduction in renal perfusion pressure, especially those with renovascular disease. In the latter group of patients, renal failure probably results from some combination of reduced poststenotic renal perfusion pressure and a unique disturbance in the autoregulation of glomerular filtration rate. Although traditionally regarded as functional and reversible, recent animal studies suggest that angiotensin-converting enzyme inhibitor-induced reductions of glomerular filtration rate may lead to progressive renal atrophy, an observation that raises concerns about the long-term safety of these agents in patients with renovascular disease. On the other hand, the deleterious consequences of angiotensin-converting enzyme inhibition in renovascular disease have been exploited as aids in the diagnosis of this disorder. Whether the adjunctive use of angiotensin-converting enzyme inhibitors will prove to be useful in screening large populations of hypertensive patients for renovascular hypertension remains to be determined. However, such adjunctive tests appear to be useful in judging the functional significance of angiographically documented renal artery stenosis.     

The natural history of atherosclerotic and fibrous renal artery disease

Summary Individuals with atherosclerotic or fibrous renal artery disease may develop renovascular hypertension and/or renal dysfunction. Traditionally, the motivation for identifying patients with renal artery stenosis was the treatment of renovascular hypertension. However, recent interest has centered on the investigation of patients suspected of having renal artery stenosis that might account for progressive azotemia. While specific forms of fibrous and/or atherosclerotic renal artery disease can lead to a compromise in renal function, differences may exist in the age of presentation, predominat sex, angiographic appearance and overal natural history. Recognition of these differences is helpful in deciding on the most likely lesion type, appropriate workup and treatment. Since renal artery stenosis can lead to radiologic and functional alterations, clinical markers of progression, such as renal size and serum creatinine measurements, are helpful in identifying patients with advancing disease. The regulators of fibrous disease progression are less clear than those responsible for atherosclerotic progression in the renal artery. Uncontrolled systemic hypertension, intrarenal hypertension, hyperlipidemia, cigarette smoking, and obesity all may potentially contribute to progressive atherosclerosis. Individuals identified with progressive azotemia due to renal artery stenosis may benefit from improved perfusion flow by renal revascularization or balloon angioplasty provided no significant parenchymal disease is present.     

Erkrankungen der Nierenarterien

Renal artery diseases are rare, but seen more often in the last years due to demographic changes and increasing non invasive diagnostics. There are different types of pathologies involving the renal arteries. The clinical manifestation is mostly hypertension or renovascular insufficiency. The main indication for endovascular therapy is hypertension, especially in young patients with fibromuscular stenosis and in elderly patients with progressive atherosclerotic stenosis with severe hypertension. The surgical therapy is left for complex reconstructions, for aneurysm resection and for simultaneous renal and aortic revascularizations in elderly patients with a high comorbidity. The indication for surgical therapy is mostly renovascular insufficiency or rather organ preservation. The different therapeutic procedures, endovascular or surgical, are demonstrated according to outcome, complications and evidence.     

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.     

Fibromuscular dysplasia of the renal artery: Management and outcome

SUMMARY: Renovascular hypertension may be caused by atherosclerotic disease or less commonly by fibromuscular dysplasia (FMD) of the renal arteries. Fibromuscular dysplasia is the commonest cause of renal artery stenosis in the younger age group and affects women predominantly. A review of our clinical database identified all patients with renovascular hypertension. All relevant clinical, biochemical and radiological findings on those with FMD were noted. the outcome of percutaneous transluminal renal angioplasty (PTRA) or reconstructive surgery was evaluated. Eight out of 62 (13%) patients with hypertension secondary to renovascular disease had FMD (all female; bilateral in four; mean age at diagnosis 37.6 years; age range 12–70 years). the mean duration of hypertension before the diagnosis of FMD was 3.3 years (range 3 months-10 years). A renal artery bruit was detected in five, hypertensive retinopathy in three and one had mild renal insufficiency. Twelve PTRAs were attempted on 10 stenotic lesions in six women. This cured the hypertension in three, while the other three have required less antihypertensive therapy. Percutaneous transluminal renal angioplasty was complicated by a trivial renal artery dissection in one, and a small upper pole infarction in another. One patient required a repeat PTRA. the other two women presented before the availability of PTRA and had successful reconstructive surgery. Fibromuscular dysplasia was the cause of hypertension in eight out of 62 (13%) patients with renovascular hypertension. Percutaneous transluminal renal angioplasty has shown encouraging results with a low complication rate. If technically feasible, PTRA should be attempted on all patients with FMD of the renal artery.     

Fibromuscular dysplasia of the renal artery: Management and outcome

Renovascular hypertension may be caused by atherosclerotic disease or less commonly by fibromuscular dysplasia (FMD) of the renal arteries. Fibromuscular dysplasia is the commonest cause of renal artery stenosis in the younger age group and affects women predominantly. A review of our clinical database identified all patients with renovascular hypertension. All relevant clinical, biochemical and radiological findings on those with FMD were noted. The outcome of percutaneous transluminal renal angioplasty (PTRA) or reconstructive surgery was evaluated. Eight out of 62 (13%) patients with hypertension secondary to renovascular disease had FMD (all female; bilateral in four; mean age at diagnosis 37.6 years; age range 12–70 years). The mean duration of hypertension before the diagnosis of FMD was 3.3 years (range 3 months–10 years). A renal artery bruit was detected in five, hypertensive retinopathy in three and one had mild renal insufficiency. Twelve PTRAs were attempted on 10 stenotic lesions in six women. This cured the hypertension in three, while the other three have required less antihypertensive therapy. Percutaneous transluminal renal angioplasty was complicated by a trivial renal artery dissection in one, and a small upper pole infarction in another. One patient required a repeat PTRA. The other two women presented before the availability of PTRA and had successful reconstructive surgery. Fibromuscular dysplasia was the cause of hypertension in eight out of 62 (13%) patients with renovascular hypertension. Percutaneous transluminal renal angioplasty has shown encouraging results with a low complication rate. If technically feasible, PTRA should be attempted on all patients with FMD of the renal artery.     

Captopril renal scintigraphy--an advance in the detection and treatment of renovascular hypertension

Despite the risks associated with renovascular hypertension and the durable benefits of revascularization, the detection of patients with renovascular hypertension and the selection of those who will benefit from interventional therapy remains a challenge. We have previously documented the reliability of captopril renal scintigraphy in predicting angiographically significant renal artery stenosis in patients suspected of having renovascular hypertension. In the present study we report our recent experience with this noninvasive technique in predicting outcome after revascularization. Captopril renal scintigraphy involves the administration of 50 mg of captopril 3 hours after a baseline technitium-99m diethylenetriaminepentaacetic acid renal scan and 1 hour before a repeat captopril renal scintigraphy scan. Nineteen of the last 70 patients with clinically suspected renovascular hypertension undergoing captopril renal scintigraphy had abnormal renal scan outcomes, and 17 had a decrease in flow or function after captopril (positive captopril renal scintigraphy). Eight of these 17 with abnormal findings on captopril renal scintigraphy underwent revascularization, and the hypertension was cured or improved in six of the eight: two of three after surgical bypass grafting and four of five after angioplasty. In the seven surviving patients with abnormal renal scan results but no change with captopril (negative captopril renal scintigraphy), improvement in hypertension after treatment occurred in only one: one of two after nephrectomy, zero of three after bypass surgery, and zero of two after angioplasty (p less than 0.05). We conclude that captopril renal scintigraphy is an accurate predictor of hypertension response to revascularization. Further evaluation of this new noninvasive technique for assessing patients with suspected renovascular hypertension appears warranted.     

Renovascular hypertension: predicting surgical cure with exercise renography

Renal artery stenosis with resultant renovascular hypertension has attracted clinical attention because the disease is potentially curable and because numerous diagnostic and therapeutic modalities compete for clinical acceptance. An exercise-mediated disturbance of renal hippurate transport was recently described, and has been implicated as having a role in nephrogenic fixed hypertension. To predict the final course of renovascular hypertension before operation we carried out a prospective study with the goal of verifying the predictive value of exercise hippurate scintigraphy. The study was to test the hypothesis that patients with disturbance of renal hippurate transport (pathologic renogram) induced by exercise would have stabilized hypertension and would continue to be hypertensive after operation. Thirty-one patients with hypertension who had unilateral or bilateral renovascular stenosis documented on angiography were referred to rest and exercise hippurate scintigrams before operation. The results of the examinations at rest served as standard and were compared with the exercise scintigrams. In 19 of the 31 (61%) patients a disturbance of transrenal hippurate transport evolved during exercise, whereas 12 (39%) patients failed to respond to exercise with altered hippurate kinetics. Twenty-six patients went on to renovascular operations; five had percutaneous transluminal angioplasty. Revascularization results differed markedly when the blood pressure response of patients with positive results on exercise (abnormal) and patients with negative results on exercise (normal) were compared. Ten of 12 patients with hypertension who had normal exercise renograms were cured. In comparison, blood pressure values were little influenced by therapy in patients with an abnormal response, where 17 of 19 patients continued to have hypertensive disease after therapy.(ABSTRACT TRUNCATED AT 250 WORDS)