Renal artery revascularization: collaborative approaches for specialists

Endovascular revascularization for atherosclerotic renal artery stenosis (RAS) is the revascularization strategy of choice for patients with hemodynamically and clinically significant renal artery stenosis. Surgical revascularization is reserved for failed endovascular therapy or concomitant abdominal aortic surgery. Endovascular renal artery stenting is associated with excellent technical success, low complication rates, and acceptable long-term patency. This technique has been proven to be beneficial for preserving kidney function and stabilizing or improving blood pressure control in selected patients. Nevertheless, deterioration in kidney function after the procedure in 10% to 20% of cases may limit the immediate benefits of this technique. Atheroembolism appears to play an important role in the cause of kidney dysfunction after renal revascularization. Renal revascularization with a distal embolic protection device is a promising strategy in reducing the risk of atheroembolism and deterioration in kidney function.     

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.     

Long-term outcome after surgical kidney revascularization for fibromuscular dysplasia and atherosclerotic renal artery stenosis

PURPOSE: At a time of minimally invasive surgery in urology, the role of surgical kidney revascularization in the management of renal artery disease has changed during the last decade. Our experience with surgical kidney revascularization, and the long-term clinical outcomes of fibromuscular dysplasia (FMD) and atherosclerotic renal artery stenosis are reviewed. MATERIALS AND METHODS: The study group comprised 140 patients with renovascular hypertension, 72 with FMD and 68 with atherosclerotic renal artery disease, who underwent surgical revascularization between 1982 and 1999. The indications for surgical revascularization were the treatment of hypertension and the preservation of renal function in 17 patients with renal artery occlusion, 55 with ostial stenosis, 52 with branch stenosis, 6 with bilateral artery stenosis, 7 with solitary kidney renal artery stenosis and 3 with solitary kidney renal artery occlusion. RESULTS: Postoperative blood pressure and renal function were monitored for 1 to 17 years (mean 11.3). Long-term blood pressure control was observed in 93% of patients with FMD and in 71% of those with atherosclerosis. Improvement or stabilization of renal function was observed in 92% of patients with FMD and in 68% of those with atherosclerosis. The preoperative estimated glomerular filtration rate compared to postoperative was significantly increased in both groups. CONCLUSIONS: Surgical kidney revascularization is effective in secondary hypertension with a high long-term efficacy in the normalization of blood pressure and in the preservation of renal function, especially in patients with a solitary or 1 functional kidney.     

Ischemic nephropathy: where are we now?

Identification and reversing the loss of kidney function beyond occlusive disease of the renal arteries poses a major clinical challenge. Recent studies indicate that atherosclerotic renal artery stenosis develops as a function of age and is commonly associated with other microvascular disease, including nephrosclerosis and diabetic nephropathy. The risks of renal artery stenosis are related both to declining kidney function and to accelerated cardiovascular disease, with increased morbidity and mortality. Newer drugs, including agents that block the renin-angiotensin system, have improved the level of BP control for renovascular hypertension. Progressive renovascular disease during medical therapy can produce refractory hypertension, congestive heart failure, and renal failure with tubulointerstitial fibrosis. Recent studies indicate a complex interplay of oxidative stress, endothelial dysfunction, and activation of fibrogenic cytokines as a result of experimental atherosclerosis and renal hypoperfusion. Advances in imaging and interventional devices offer major new opportunities to prevent progressive loss of kidney function. Recent series indicate that although 25 to 30% of patients with impaired renal function can recover glomerular filtration after revascularization, many have no apparent change in kidney function and 19 to 25% experience a significant loss of kidney function, in some cases as a result of atheroemboli. To select patients who are most likely to benefit from vascular intervention, clinicians should understand the pathophysiology of developing ischemic nephropathy and the potential hazards of revascularization in the setting of diffuse atherosclerotic disease. Further research should be directed toward identification of critical disease, regulation of fibrogenesis, and the interaction with other atherosclerotic processes.     

Prognostic significance of intrarenal resistance indices in patients with renal artery interventions: a preliminary duplex sonographic study

No non-invasive test can predict the clinical outcome of renal revascularization procedures. Because duplex sonographic measurements of intrarenal flow patterns reflect the resistance to flow within the kidney, the prognostic value of the cortical end-diastolic to peak systolic (d/s) velocity ratio was investigated in patients undergoing intervention for renal artery stenosis. The clinical and duplex sonographic data on 32 patients with 35 interventions (30 percutaneous transluminal angioplasties and five operations) on 42 renal artery sides were analysed. Twenty-three patients had atherosclerotic renal artery stenosis and nine patients had fibromuscular dysplasia resulting in ≥60% renal artery stenosis. Measurements of the renal to aortic velocity ratio and cortical d/s ratio were performed before and after intervention. In the atherosclerotic patients, three interventions were clinically and technically successful, eight were technically successful but clinical failures, and 14 were clinically and technically unsuccessful. In the fibromuscular dysplasia patients, eight interventions were clinically and technically successful, and two were clinically and technically unsuccessful. The difference between the corresponding d/s ratios for atherosclerotic and fibromuscular dysplasia sides was significant on both the treated and not-treated sides (P < 0.02, two-tailed unpaired t-test). None of the 11 clinically successful procedures had a d/s ratio below 0.3, compared with seven values below 0.3 in the 24 clinically unsuccessful interventions (P = 0.05, one-tailed Fisher's exact test). It is concluded that: (1), a d/s ratio below 0.3 correlates with clinical failure in subsequent treatment of hypertension by renal revascularization, while a value above 0.3 has no prognostic significance; (2), despite technical success, not all atherosclerotic patients have clinical success from renal artery interventions; (3), in fibromuscular dysplasia patients, all clinical failures of renal artery interventions are associated with technical failures; and (4), the difference in d/s ratio between atherosclerotic and fibromuscular dysplasia patients may be a consequence of the more advanced age, longer duration of hypertension and additional risk factors in atherosclerotic patients.     

The Contemporary Role of Extra-anatomical Surgical Renal Revascularization in Patients with Atherosclerotic Renal Aretery Disease

We delineate the current role of extra-anatomical revascularization techniques in the treatment of patients with atherosclerotic renal artery stenosis. There are 2 components to this study. In part 1 all abdominal aortograms performed between 1989 and 1993 were reviewed to document the presence of significant abdominal aortic and visceral arterial atherosclerosis in patients with atherosclerotic renal artery stenosis. A total of 254 patients with atherosclerotic renal artery stenosis was identified. Among 44 patients with severe unilateral disease the incidence of significant abdominal aortic atherosclerosis was 75 percent. The incidence of significant (greater than 50 percent) stenosis of the celiac, right common iliac and left common iliac arteries was 52 percent, 32 percent and 27 percent, respectively. In 129 patients with severe atherosclerotic renal artery stenosis bilaterally or in a solitary kidney the incidence of significant abdominal aortic atherosclerosis was 81 percent, and the incidence of significant (greater than 50 percent) stenosis of the celiac, right common iliac and left common iliac arteries was 59 percent, 57 percent and 59 percent, respectively. These data indicate that hepatorenal, splenorenal and iliorenal bypass cannot be performed in many patients with atherosclerotic renal artery stenosis due to significant disease involving the donor vessels for these operations.

In part 2, all patients undergoing surgical renal revascularization with an extra-anatomical bypass operation between 1980 and 1992 were reviewed. A total of 175 operations was done in 171 patients, including hepatorenal bypass in 59, splenorenal bypass in 54, iliorenal bypass in 37, thoracic aortorenal bypass in 23, renal autotransplantation in 1 and superior mesentero-renal bypass in 1. There were 5 operative deaths (2.9 percent) and 7 cases of postoperative graft thrombosis (4 percent). All patients with poorly controlled hypertension were cured or improved postoperatively. Among patients with ischemic nephropathy, postoperative renal function improved in 35 percent, remained stable in 47 percent and deteriorated in 18 percent. Extra-anatomical techniques remain an important component of the surgical armamentarium for atherosclerotic renal artery stenosis. Thoracic aortorenal bypass is a useful new approach in patients with significant celiac and iliac occlusive disease.     

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.     

Trends in reconstruction for atherosclerotic renal vascular disease

Twenty-eight patients underwent renal vascular reconstruction for atherosclerotic renal vascular stenosis. Ten patients had therapeutic renal artery reconstruction for isolated renal artery stenosis causing severe hypertension, nine patients had therapeutic renal artery reconstruction for severe hypertension combined with simultaneous aortic reconstruction, and nine patients had prophylactic renal artery reconstruction for renal artery stenosis combined with simultaneous aortic reconstruction. Ninety percent of patients undergoing therapeutic renal revascularization procedures for hypertension were cured or improved. The 10 patients undergoing prophylactic renal artery reconstruction combined with aortic reconstruction had an average 72 percent reduction in the diameter of the vessel. Dacron side grafts sutured to the aortic graft were used for revascularization in each of the patients with prophylactic revascularization and was found to be an expedient means of reconstruction with good patency rates. No increased morbidity or mortality rate was noted in the prophylactic group. We believe that prophylactic revascularization should be carried out in patients with atherosclerotic high-grade stenosis of the renal arteries to prevent hypertension and preserve renal function.     

Surgical renal artery reconstruction after percutaneous transluminal angioplasty

Percutaneous transluminal renal angioplasty (PTRA) is a controversial treatment for renal artery stenosis. This article discusses whether or not a prior attempt at PTRA compromises a subsequent elective or emergent surgical revascularization. Thirteen patients had surgical renal artery reconstruction after one or more PTRAs. Eight of the patients were treated because of atherosclerotic renal artery disease whereas five had a form of fibromuscular dysplasia. Five patients had renal artery injury directly related to the angioplasty. Four of these kidneys were saved. Eight patients were treated from 6 to 920 days after PTRA because of recurrent stenosis or occlusion of the renal artery. Only one of these kidneys was lost, an attempt at revascularization of a small kidney that failed to resume function. A prior attempt at PTRA did not compromise the ability of subsequent surgical revascularization to ameliorate hypertension. We conclude that surgical renal revascularization is not made less likely to succeed by a previous attempt at PTRA; even if the renal artery is thrombosed or perforated during the procedure, a reasonable chance of renal salvage is obtained by immediate surgical revascularization.     

Atheroembolic renal disease: effect on morbidity and survival after revascularization for atherosclerotic renal artery stenosis

PURPOSE: Atheroembolic renal disease is increasingly found in older patients with general atherosclerosis. We evaluated the impact of atheroembolic renal disease on morbidity and survival after surgical revascularization for atherosclerotic renal artery stenosis. MATERIALS AND METHODS: The study group comprised 44 patients who underwent surgical revascularization for atherosclerotic renal artery stenosis and concomitant intraoperative renal biopsy. Renal biopsy specimens were reviewed by a pathologist and evaluated for the presence or absence of atheroemboli, and the presence and severity of arteriolar nephrosclerosis. Postoperative patient data were reviewed to evaluate survival, and the incidence of renal and systemic morbid events. Patients were followed for 1 to 14.5 years (median 6.2) after surgical revascularization. RESULTS: Atheroembolic renal disease was identified in the intraoperative biopsy specimen in 16 patients (36%, group 1) and was absent in 28 (64%, group 2), termed groups 1 and 2. Atheroembolic renal disease correlated significantly with decreased patient survival. The 5-year survival in groups 1 and 2 was 54 and 85%, respectively (p = 0.011). Similarly the incidence of systemic atherosclerotic complications was significantly higher in group 1 than group 2 (86 versus 58%, p <0.05). In addition, renal or renovascular complications developed in more group 1 than group 2 patients (p = 0.07). There was no significant association between the presence or severity of arteriolar nephrosclerosis and postoperative survival or morbid events. CONCLUSIONS: Our results indicate that atheroembolic renal disease is associated with decreased survival and an increased incidence of atherosclerotic morbid events after surgical revascularization for atherosclerotic renal artery stenosis. This information may be useful for therapeutic decision making in patients with atherosclerotic renal artery stenosis.     

Ischemic nephropathy. Epidemiology and clinical implications.

Renal dysfunction secondary to stenosis of the renal arteries is an entity that is underdiagnosed but becoming increasingly recognized. This condition probably accounts for a large number of patients in dialysis programs. Hypertension is not an essential component of this disease. Progression of renal artery stenosis with deterioration of renal function is the natural course. This progression can be reversed with surgical or percutaneous revascularization of the ischemic kidneys with a high degree of success in preserving or restoring kidney function.     

Extra-anatomic renal revascularization in patients with renal artery stenosis and abdominal aortic occlusion

Thirteen patients with atherosclerotic renal artery stenosis and total abdominal aortic occlusion underwent extra-anatomic surgical renal revascularization without aortic replacement. Renal artery stenosis was present unilaterally (n = 2), bilaterally (n = 7), or in a solitary kidney (n = 4). Surgical renal revascularization was indicated for treatment of severe hypertension in all patients and for preservation of renal function in 10 patients. The level of abdominal aortic occlusion was suprarenal (n = 3), perirenal (n = 2), or infrarenal (n = 8). All patients had extensive collateral vascular supply to the lower extremities with absent (n = 7) or mild (n = 6) claudication. Surgical renal ervascularization was achieved with hepatorenal bypass (n = 6), mesenterorenal bypass (n = 4), or splenorenal bypass (n = 3). None of the patients underwent concomitant aortic replacement. There were no operative deaths. Postoperatively, hypertension was improved in 10 patients, unchanged in 2 patients, and worse in 1 patient. Renal function was improved in 8 patients, stable in 2 patients, and worse in 3 patients. After surgical renal revascularization, no patient required aortic replacement, while 1 patient underwent extra-anatomic revascularization of the lower extremities. We conclude that some patients with renal artery stenosis and abdominal aortic occlusion can be managed by surgical renal revascularization alone without a more extensive and potentially hazardous aortic replacement. In these patients, extra-anatomic techniques can allow safe and successful surgical renal revascularization while avoiding surgery on the diseased aorta.     

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 revascularization by splenic artery implantation in the dog

36 mongrels were subjected to splenic artery implantation into the left kidney. A stenosis of the left renal artery was created in 33 of the dogs. The revascularization process from the implanted artery was studied by angiography in vivo and ex vivo, by histological examination and by blood flow measurements. After creation of the stenosis and eventual occlusion of the left renal artery, newly formed intrarenal vessels could be demonstrated next to the implanted artery. These vessels formed communications between the splenic and intrarenal arteries. The experimental animals survived contralateral nephrectomy and ligature of the ipsilateral renal artery with a slight or moderate elevation of the serum creatinine level, provided that a slowly progressing stenosis of the renal artery was created.     

Chronic renal artery occlusion: Nephrectomy versus revascularization

Purpose: The surgical management of chronic atherosclerotic renal artery occlusion (RA-OCC) was studied. Methods: From January 1987 through December 1996, 397 consecutive patients were treated for atherosclerotic renal artery disease. Ninety-five hypertensive patients (mean blood pressure, 204 ± 31/106 ± 20 mm Hg; mean medications, 3.0 ± 1.1 drugs) were treated for 100 RA-OCCs. Eighty-four (88%) patients had renal dysfunction, defined by serum creatinine levels ≥1.3 mg/dL (mean serum creatinine level, 2.8 ± 2.0 mg/dL). Demographic characteristics, operative morbidity and mortality, blood pressure/renal function response, and postoperative decline in renal function were examined and compared with that of 302 patients treated for renal artery stenosis (RAS). Results: After operation, there were 5 perioperative deaths (5.2%), 2 (2.8%) after revascularization and 3 (12%) after nephrectomy (P = .11), compared with 12 (4.0%) perioperative deaths in the RAS group (P = .59). After controlling for important covariates, estimated survival and blood pressure benefits did not differ between RA-OCC patients treated by nephrectomy or revascularization (P = .13; 87% vs 92%, P = .54). Excretory renal function was considered improved in 49% of 79 RA-OCC patients with renal dysfunction, including 9 patients removed from dialysis-dependence. Among patients treated for unilateral disease, revascularization for RA-OCC was associated with significant improvement in renal function (P < .01); however, nephrectomy alone did not increase renal function significantly. Improved renal function after operation was associated with a significant and independent increase in survival (P < .01) and dialysis-free survival (P < .01) among patients treated for RA-OCC. In addition, blood pressure benefit, renal function response, and estimated survival did not differ significantly after reconstruction for RA-OCC or RAS. Conclusion: Among hypertensive patients treated for RA-OCC, equivalent beneficial blood pressure response was observed after both revascularization and nephrectomy. In patients who underwent bilateral renal artery revascularization, the change in excretory renal function attributable to repair of RA-OCC cannot be defined. In patients treated for unilateral disease, however, improvement in function was observed only after revascularization. Moreover, improved renal function demonstrated a significant and independent association with improved survival. This experience supports renal revascularization in preference to nephrectomy for RA-OCC in select hypertensive patients when a normal distal artery is demonstrated at operation. (J Vasc Surg 1999;29:140-9.)     

Can intrarenal duplex waveform analysis predict successful renal artery revascularizaion?

Purpose: No currently available noninvasive test can preoperatively predict a successful outcome to renal revascularization. Resistance measurements from the renal parenchyma obtained with duplex sonography reflect the magnitude of intraparenchymal disease, and patients with extensive intrarenal disease may respond less favorably to revascularization. To address this question, we reviewed our (primarily) operative experience in patients undergoing renal artery revascularization, and compared the blood pressure (BP) and renal function response with resistance measurements obtained from the kidney both before and after revascularization. Methods: During a 56-month period, 31 consecutive renal artery revascularizations (25 surgical and 6 percutaneous angioplasties) were performed in 23 patients (21 atherosclerotic, 2 fibromuscular dysplasia). Duplex sonography was performed in each patient before and after revascularization, and parenchymal diastolic/systolic (d/s) ratios were calculated. BP and renal function response to intervention were compared with measurements of intrarenal flow patterns before and after revascularization. Results: Mean parenchymal peak systolic velocity was significantly higher after repair in all patients (pre-repair: 19.5 ± 1.3, postrepair: 27.2 ± 1.7; P<.0001). Despite this, there were no statistical differences between preoperative and postoperative parenchymal d/s ratios. A favorable (cured or improved) BP response was seen in 81% (17 of 21) of revascularizations performed for hypertension. Among these successes, parenchymal d/s ratios were in the normal range (ie, ≥0.30) both before and after repair (mean pre-repair: 0.34 ± 0.03, mean postrepair: 0.31 ± 0.03; not significant). In 4 patients in which BP failed to improve after intervention, the d/s ratio was abnormal before surgery (<0.3), and remained so after revascularization (mean preoperative d/s ratio: 0.18 ± 0.04, mean postoperative d/s ratio: 0.11 ± 0.04; P = .003). Mean preoperative parenchymal d/s ratios were significantly higher in all patients with a successful BP response when compared with failures (P = .048). Similarly, among patients with single artery repairs, mean preoperative d/s ratios approached significance in successes vs. failures (success: 0.40 ± 0.03, failure: 0.21 ± 0.03; P = .054). A decrease in serum creatinine greater than or equal to 20% was seen in 8 of 18 patients (44%) with ischemic nephropathy. These patients also had normal d/s ratios preoperatively (mean 0.39 ± 0.04), whereas the 10 patients who failed to improve had significantly lower ratios (mean 0.24 ± 0.03; P = .041). Kidney length did not correlate with d/s ratio. Conclusion: Although we do not believe that duplex sonographic measurement of intrarenal flow patterns alone is an accurate means of assessing main renal artery occlusive disease, the resistive indices seem to reflect the magnitude of intraparenchymal disease, and thus may provide important prognostic information for patients undergoing surgical revascularization. Our data suggest that a preoperative d/s ratio below 0.3 correlates with clinical failure relative to BP and renal function responses. (J Vasc Surg 1998;28:471-81.)     

Ischemic nephropathy: diagnosis and treatment

Recent epidemiologic studies have shown that ischemic nephropathy secondary to stenosis or obstruction of the main renal arteries in the cause of renal insufficiency in a growing number of subjects. The clinicians dealing with renovascular disease need non-invasive diagnostic tools and effective therapeutic measures to successfully face the problem. Duplex ultrasound scanning is a non-invasive, non expensive diagnostic tool and when an experienced, dedicated technologist is available, it should be suggested as the first-step test. Magnetic resonance angiography and spiral CT angiography play an ancillary role in detecting patients with renovascular disease. Captopril-enhanced (CE) scintigraphy when positive indicates the activation of intrarenal renin-angiotensin system and may be useful in detecting patients with renal artery stenosis. Moreover, CE scintigraphy can play an important role in the choice between the revascularization and a wait-and-see approach. As a matter of fact, the presence of an activated intrarenal renin-angiotensin system furnishes theoretical as well practical reasons in favour of the revascularization. In the recent years percutaneous transluminal renal angioplasty has become the cornerstone of therapeutic strategy. The introduction of the metallic stent has dramatically improved its efficacy in ostial stenoses and has reduced the indication for surgical revascularization.     

Novel noninvasive techniques for studying renal function in man

Renal artery stenosis is a major cause of renovascular hypertension in humans, and may lead to ischemic nephropathy and end-stage renal disease. The mechanisms responsible for the progressive renal functional and structural alterations have not been fully elucidated, partly because of the lack of reliable, noninvasive techniques capable of quantifying renal regional hemodynamics and function distal to a stenosis in the renal artery. Novel imaging tools now enable quantification of concurrent intrarenal (cortical and medullary) hemodynamics, segmental nephron dynamics (intratubular transit times and fluid concentrations), and renal function in the intact kidney. Fast computed tomography (CT) scanners, such as electron beam CT, allow discrimination of subtle alterations in renal perfusion and segmental nephron function consequent to changes in renal perfusion pressure, both within and below the range of renal blood flow autoregulation. This technique provides an opportunity to define intrarenal perfusion patterns and function in animals and patients with renal artery stenosis, and may provide insight into the effects of chronic unilateral or bilateral renovascular disease on both the hypoperfused and contralateral kidneys. This methodology may thereby prove to be very useful in the evaluation of renal disease in general, and the renovascular hypertensive patient in particular.     

Changing concepts in the surgical management of renovascular hypertension

Summary As newer surgical techniques and concepts have emerged, including revascularization of the totally occluded renal artery and alternatives to aortorenal bypass (hepatic, splenic, or iliac artery to renal artery grafts), our patient population has changed dramatically. Patients with diffuse atherosclerotic disease, bilateral renal artery stenosis, totally occluded renal arteries, and azotemia are more commonly referred for renal revascularization, thereby changing the indications for operation and the results that can be anticipated. Although our results in patients undergoing surgery solely for uncontrollable hypertension or renal failure have been successful, much work needs to be done to improve the results obtained in patients with a combination of uncontrollable hypertension and renal failure.