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Acs0622 Open Procedures For Renovascular Disease


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  • 1. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 22 OPEN PROCEDURES FOR RENOVASCULAR DISEASE — 1 22 OPEN PROCEDURES FOR RENOVASCULAR DISEASE Matthew S. Edwards, M.D., Juan Ayerdi, M.D., and Kimberley J. Hansen, M.D., F.A.C.S. Until comparatively recently, intervention for renovascular disease Disease] is liberally used as an alternative to open renal artery focused entirely on hypertension. However, the introduction of revascularization, but the data currently available suggest that it potent new antihypertensive agents and percutaneous endovascu- should be employed selectively.The best results with PTRA alone lar methods of management has led to substantial changes in atti- have been achieved with nonostial atherosclerotic renal artery tudes to and indications for management of renovascular disease. lesions and medial fibroplasia of the main renal artery. Suboptimal Today, open surgical repair is commonly reserved for (1) patients results have been achieved with hypoplastic (i.e., developmental) who have severe hypertension despite optimal medical therapy, (2) lesions, fibrodysplasia of the intimal and perimedial variety, ostial patients in whom percutaneous transluminal renal artery angio- atherosclerotic renal artery lesions, and renal artery occlusions. plasty (PTRA) fails or who have disease patterns that are not For ostial renal artery atherosclerosis, some surgeons have advo- amenable to PTRA, and (3) patients who have renovascular dis- cated PTRA with primary endoluminal stenting in an effort to ease associated with excretory renal insufficiency (i.e., ischemic improve results; however, the results of PTRA and primary stent- nephropathy).1 ing in this setting have been inferior to those of open operative The experience of our center (Wake Forest University School of repair. Consequently, in the majority of cases of ostial atheroscle- Medicine) in the management of more than 850 patients over a rosis in combination with renal insufficiency, we advise operative 16-year period indicates that atherosclerotic renovascular disease intervention for good-risk patients. frequently exists in combination with diffuse extrarenal athero- These recommendations are not absolute. Decisions regarding sclerosis and renal insufficiency. In one study, bilateral atheroscle- therapy for renovascular disease must be individualized. Factors rotic renal artery lesions were present in two thirds of patients, and contributing to the choice of treatment include the expected mor- complete renal artery occlusion was present in more than one bidity and mortality of operative repair and the presence of pre- third.2 Although practitioners frequently cite selected data to sup- dictors of death and dialysis dependence at follow-up. In this port a particular management scheme in this setting, the question regard, severe left ventricular dysfunction with clinical congestive of what constitutes optimal management of atherosclerotic reno- heart failure, diabetes mellitus, and uncorrectable azotemia have vascular disease responsible for either hypertension or renal insuf- all been shown to be significant and independent predictors of ficiency is still unanswerable.To date, there have been no prospec- reduced dialysis-free survival.2,3 tive, randomized trials that compare the best medical manage- ment with PTRA and with open surgical repair. Operative Planning Preoperative Evaluation SURGICAL STRATEGY Evaluation and diagnosis of renovascular hypertension and reno- Our use of open surgical methods to treat atherosclerotic reno- vascular renal insufficiency (i.e., ischemic nephropathy) are discussed vascular disease is based on several guiding principles [see Table 1]. in more detail elsewhere, as are general issues related to the We consider severe hypertension a prerequisite for open operative question of medical versus surgical therapy. management and do not perform prophylactic renal artery repair INDICATIONS FOR INTERVENTION The recognition of both the progressive nature of the athero- Table 1—Recommended Principles for sclerotic renovascular lesions seen in combination with severe Contemporary Surgical Management of hypertension and the deterioration of renal function seen in select- Renovascular Disease10 ed patients who are managed medically lends support to the idea that renal artery intervention is indicated when either renovascu- Renal artery repair is done on an empirical, but not prophylactic, basis lar hypertension or ischemic nephropathy is present. In our view, Complete renal artery repair is done in one operation when feasible; bilateral ex vivo reconstruction may be staged renal artery intervention is appropriate in patients with severe Direct aortorenal methods of reconstruction are preferred hypertension and, specifically, in all patients who have severe hy- Nephrectomy is reserved for nonreconstructable disease in a pertension in combination with excretory renal insufficiency (i.e., nonfunctioning kidney ischemic nephropathy). Open operative management is preferred Combined aortic reconstruction is limited to clinically significant disease for children and young adults and for patients with bilateral reno- Intraoperative duplex sonography is performed to assess technical vascular disease, especially if renal artery occlusion is present.2 success PTRA [see 6:16 Endovascular Procedures for Renovascular
  • 2. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 22 OPEN PROCEDURES FOR RENOVASCULAR DISEASE — 2 a b c Figure 1 Aortorenal bypass.8 Technique for end-to-side (a, b) and end-to-end (c) aortorenal bypass grafting. The length of arteriotomy is at least three times the diameter of the artery to prevent recur- rent anastomotic stenosis. For the anastomosis, 6-0 or 7-0 monofilament polypropylene sutures are used in continuous fashion, under loupe magnification. If the apex sutures are placed too deeply or with excess advancement, stenosis can be created, posing a risk of late graft thrombosis. Operative Technique in patients who are not hypertensive. Although we employ renal vein renin assays to guide management of unilateral lesions in many Various open surgical techniques are used to correct athero- cases, we typically perform empirical renal artery repair without sclerotic renovascular disease; however, no single repair technique functional studies when the hypertension is severe or uncontrolled is optimal for all renovascular lesions. The best approach to renal and when renal artery disease is bilateral or involves a solitary kid- artery reconstruction in any given case depends on patient char- ney. We attempt to correct all hemodynamically significant reno- acteristics, the pattern of renal artery disease, and the presence or vascular disease in a single operation; we perform staged repair only absence of associated aortic lesions that may have to be corrected in cases in which the disease necessitates bilateral ex vivo recon- simultaneously. The open procedures most commonly performed struction. Because the lower limit of renal function retrieval is not to treat renovascular disease are (1) aortorenal bypass, (2) renal known but improved renal function is known to be the strongest artery thromboendarterectomy, and (3) renal artery reimplanta- predictor of dialysis-free survival, we reserve nephrectomy for tion. In general, aortorenal bypass is the most versatile of these patients who have an unreconstructable lesion in a renal artery sup- procedures.Transaortic thromboendarterectomy may be especial- plying a nonfunctioning kidney (i.e., a kidney providing less than ly useful when ostial atherosclerosis ends within 1 cm of the origin 10% glomerular filtration on renography).4 In the majority of open of the renal artery and involves multiple renal arteries. Renal operative repairs, we employ direct aortorenal reconstruction artery reimplantation is often particularly appropriate for the cor- methods; we seldom use indirect (splanchnorenal) methods, rection of renovascular disease in children and adolescents, in that because celiac axis stenosis is present in 40% to 50% of patients concerns regarding graft material are eliminated. and bilateral repair is required in more than 50%.2 Regardless of With all of these reconstruction techniques, multiple small the method of reconstruction employed, we perform intraoperative doses of mannitol are administered intravenously during perirenal renal duplex sonography as a completion study to look for any aortic and renal artery dissection. Mannitol is given both before technical errors in the repair that might lead to restenosis or occlu- and after periods of warm renal ischemia up to a total dose of 1 sion. Failed renal artery repair has been associated with a signifi- g/kg. During cross-clamping of the aorta and the renal artery, the cant and independent risk of eventual dependence on dialysis.5 patient is given heparin, 100 U/kg, to establish systemic anticoag-
  • 3. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 22 OPEN PROCEDURES FOR RENOVASCULAR DISEASE — 3 ulation. When a purely autogenous reconstruction is performed, eter of the smallest conduit, and the ends of the conduit should be antibiotics are unnecessary; however, when a prosthetic graft is widely spatulated to guard against late suture line stenosis. The employed, administration of a first-generation cephalosporin is proximal anastomosis is usually made with a continuous 6-0 begun 2 hours before operation and continued for 24 hours. monofilament polypropylene suture, and the distal anastomosis is created with a continuous 7-0 or 8-0 monofilament polypropylene AORTORENAL BYPASS suture. Aortorenal bypass [see Figure 1] may be performed with either THROMBOENDARTERECTOMY an autogenous conduit or a prosthetic graft. If an entirely autoge- nous repair is possible, we prefer to use a reversed segment of the Thromboendarterectomy of the renal arteries and the perirenal greater saphenous vein as the conduit. If the saphenous vein is too aorta may be performed via either a transrenal or a transaortic narrow (i.e., < 4 mm in diameter) or of inadequate quality, a 6 approach. When the renal artery atheroma extends 1 cm or less mm thin-walled polytetrafluoroethylene (PTFE) graft is used from the ostium and involves both or multiple renal arteries, the instead. In either case, the infrarenal aorta is dissected and transaortic technique [see Figure 2] is especially useful. With both clamped proximally and distally, and a longitudinal elliptical open- endarterectomy techniques, extensive aortic exposure is required. ing is created anterolaterally in the aortic wall (e.g., with two or The aorta proximal to the origin of the superior mesenteric artery three applications of a 5.2 mm aortic punch). If required, a local (SMA) is exposed and controlled. This exposure is facilitated by endarterectomy at the site of the anastomosis may be performed partially dividing the aortic crura and controlling the SMA with a through this opening. Silastic loop. The proximal and distal anastomoses are then created. Currently, the majority of aortorenal endarterectomies are per- Although end-to-side distal renal artery anastomoses were com- formed through a longitudinal aortotomy extending from a point monly performed at one time, current aortorenal bypass tech- 2 to 3 cm below the renal arteries to the base of the SMA. A sleeve niques typically employ end-to-end distal renal artery anasto- of aortic atheroma is created, then divided sharply at the base of moses. For both the proximal and the distal anastomosis, the the SMA proximally and well below the most inferior renal artery length of the arteriotomy should be at least three times the diam- distally. After the aortic endarterectomy is completed, an eversion- a b Left Renal Artery SMA SMA IMA Figure 2 Thromboendarterectomy.8 Exposure for a longitudinal transaortic endarterectomy is obtained via the standard transperitoneal approach. The duodenum is mobilized from the aorta later- ally in the standard fashion; alternatively, for more complete exposure, the ascending colon and the small bowel are mobilized. (a) Dotted line shows the location of the aortotomy. (b) The plaque is transected proximally and distally, the renal arteries are everted, and the atherosclerotic plaque is removed from each renal ostium. The aortotomy is typically closed with a continuous 4-0 or 5-0 polypropylene suture. (IMA—inferior mesenteric artery)
  • 4. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 22 OPEN PROCEDURES FOR RENOVASCULAR DISEASE — 4 a b c d Figure 3 Renal artery reimplantation.9 (a) When the renal artery is redundant and the disease involves the orifice of the renal artery, it is usually possible to reimplant the vessel at a lower level. Dotted lines indicate the location of the aortotomy and the point where the renal artery is divided. (b) An elliptical opening is created in the aortic wall, and a local endarterectomy is done as required. (c) A monofilament suture is placed in the aortic wall. (d) The native renal artery is ligated, proximally spatulated, and reimplanted. type endarterectomy is performed for each of the renal arteries. Although this technique has only limited applicability to the The surgical assistant retracts the anterior lip of the aortic wall and treatment of atherosclerotic renovascular disease in adults, it may inverts the renal artery into the aorta, and the operating surgeon be particularly useful for this purpose in children and young ado- retracts the renal artery atheroma while gently pushing the lescents, who often have congenital or developmental lesions that remaining renal artery away with a dissector. In this manner, the involve the renal artery orifice. The main advantage of reimplan- end point of the endarterectomy can easily be visualized to con- tation is that it obviates concerns regarding the durability of the firm that the endarterectomy is complete.The endarterectomy site renal artery conduit. is then irrigated with heparinized saline, and the longitudinal aor- SPLANCHNORENAL BYPASS totomy is closed with a continuous 4-0 or 5-0 monofilament polypropylene suture. Indirect, or splanchnorenal, bypass [see Figure 4] is an uncom- Both transrenal and transaortic thromboendarterectomy are mon procedure at our center. In large part, its relative rarity is a contraindicated if aneurysmal degeneration of the perirenal aorta reflection of the frequent presence of simultaneous disease of the is present or if there is transmural calcification at the site of celiac axis and the frequent need for bilateral renal artery recon- endarterectomy. struction in combination with aortic repair. In addition, we believe that this approach does not yield long-term patency equivalent to RENAL ARTERY REIMPLANTATION that provided by direct aortorenal reconstruction. Consequently, In the course of renal artery exposure, the vessel is dissected these indirect bypass techniques are reserved for a selected sub- from its aortic origin to its primary bifurcation. On occasion, after group of high-risk patients. complete dissection, the vessel is found to have sufficient redun- Hepatorenal bypass is most frequently performed through a dancy to allow tension-free reimplantation into the infrarenal right subcostal incision, splenorenal bypass through a left sub- aorta [see Figure 3]. As in a renal artery bypass [see Aortorenal costal incision. In either procedure, the patient is positioned with Bypass, above], an elliptical section of the aortic wall is resected, a roll beneath the ipsilateral flank, with the operating table flexed and a widely spatulated aortorenal anastomosis is fashioned. and the ipsilateral arm padded and tucked to the side.The incision
  • 5. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 22 OPEN PROCEDURES FOR RENOVASCULAR DISEASE — 5 may be extended to the contralateral semilunar line and into the function in 60% of occluded renal arteries that underwent opera- ipsilateral flank as necessary for exposure. In a hepatorenal bypass, tive repair.4 a greater saphenous vein graft is usually employed, originating INTRAOPERATIVE RENAL DUPLEX ULTRASONOGRAPHY from the common hepatic artery and coursing posterior to the portal triad and anterior to the vena cava before the end-to-end The surgeon’s technique plays a dominant role in determining renal artery anastomosis [see Figure 4]. A splenorenal bypass may patency after renal artery reconstruction. To look for technical be created either in a similar fashion (i.e., with a greater saphenous errors at the time of operation, we employ intraoperative renal vein graft) or by anastomosing the transected splenic artery direct- duplex ultrasonography. A 10.0/5.0 mHz compact linear array ly to the left renal artery [see Figure 5]. If the latter approach is probe with Doppler color-flow capability is placed within a sterile taken, the collateral circulation to the spleen is sufficient to main- sheath that has a latex tip containing sterile gel.The operative field tain splenic viability. is flooded with warm saline solution, and B-scan images are obtained from the sites of aortic control and of renal artery repair. NEPHRECTOMY All defects noted on the B-scan images are then examined in both In patients with renovascular renal insufficiency or ischemic longitudinal and transverse projections. Doppler samples are nephropathy, an incremental increase in excretory renal function obtained proximal and distal to the lesions to determine their after operation is the dominant determinant of dialysis-free sur- hemodynamic significance.6 In 249 consecutive renal artery vival. As noted [see Operative Planning, Surgical Strategy, above], repairs with anatomic follow-up, 10% had a focal increase in peak we reserve nephrectomy for patients in whom an unrecon- systolic velocities consistent with residual stenosis.2 Each defect structable renal artery is supplying a nonfunctioning kidney.When was revised immediately, and in each case, a significant defect was the renal artery is occluded, reconstruction is performed if the dis- found. At 12 months after operation, primary patency of the renal tal renal artery is normal at the time of surgical exploration. Past reconstruction was observed in 97% of repairs.This product-limit recommendations regarding the management of renal artery oc- estimate of patency is stable up to 8 years after operation. clusion have emphasized kidney length, distal renal artery recon- stitution, and the appearance of a nephrogram during angiography Outcome Evaluation as criteria for determining whether reconstruction is indicated. Our practice, however, has been to perform renal artery recon- Surgical repair of atherosclerotic renovascular disease can be struction whenever a normal distal renal artery is demonstrated. accomplished with a high rate of success and sustained long-term In a study employing this strategy, we reported retrieval of renal patency. With proper patient selection, the majority of patients a b c Figure 4 Hepatorenal bypass.9 (a) Shown is exposure of the common hepatic artery and the proximal gastroduodenal artery in the hepatoduodenal ligament in preparation for hepatorenal bypass (typically through a right subcostal skin incision). (b,c) The reconstruction is completed by placing a greater saphenous vein interposition graft between the side of the hepatic artery and the distal end of the transected right renal artery.
  • 6. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 22 OPEN PROCEDURES FOR RENOVASCULAR DISEASE — 6 Splenic Artery a b Left Renal Artery Figure 5 Splenorenal bypass.9 (a) Shown is exposure of the left renal hilum in preparation for splenorenal bypass (typically obtained through a left subcostal incision). The pancreas has been mobilized along its inferior margin and retracted superiorly. (b) The transected splenic artery is anastomosed to the transected left renal artery in an end-to- end manner. A splenectomy is not routinely performed. demonstrate beneficial blood pressure response and renal function perioperative mortality demonstrated significant and independent response, albeit with perioperative mortality and morbidity that associations with advanced age and clinical congestive heart fail- vary according to the complexity of the procedure. ure. The estimated primary patency rate for all 720 renal artery In a 2002 report, we reviewed our center’s experience with 500 reconstructions was 97% at 8 years’ follow-up. consecutive patients who underwent open surgical repair for treat- ment of atherosclerotic renovascular disease between January HYPERTENSION RESPONSE 1987 and December 1999.2 These patients included 254 women Early blood pressure response was estimated on the basis of and 246 men, with a mean age of 65 ± 9 years. Each patient had ambulatory blood pressure values and medication requirements severe hypertension.The mean preoperative blood pressure for the determined at least 1 month after operative repair. Among surgi- group was 200 ± 35/104 ± 21 mm Hg. Most of the patients had cal survivors, 12% were considered cured, 73% were considered diffuse extrarenal atherosclerosis. A total of 81% had at least one improved, and 15% were considered failed [see Table 3]. manifestation of cardiac disease; 34% had a history of significant cerebrovascular disease; and 78% were considered to have at least RENAL FUNCTION RESPONSE mild renal insufficiency, as evidenced by a serum creatinine con- centration of 1.3 mg/dl or greater. Ischemic nephropathy was seen A significant change in excretory renal function was defined in 244 patients (49%), including 40 patients who were dependent as a change of at least 20% in the estimated glomerular filtration on dialysis before operation. rate (EGFR), measured at least 3 weeks after repair. Of patients Angiographic evaluation demonstrated the presence of bilater- al renal artery disease in 60% of these atherosclerotic patients.The renal artery lesion was considered ostial in 97% of cases, and 16% Table 2 Summary of Operative Management of of renal arteries were completely occluded. A total of 720 renal Atherosclerotic Renovascular Disease2 artery reconstructions were performed [see Table 2]. Aortorenal by- pass was performed in two thirds of the repairs, and two thirds of Total renal reconstructions 720 these bypasses were done with venous grafts.Thromboendarterec- Aortorenal bypass 384 tomy was performed in almost one third of the cases. Renal artery Venous graft 204 reimplantation was performed in 56 instances, splanchnorenal by- PTFE graft 159 pass in only 13 instances. Although there were 124 renal artery oc- Dacron graft 21 clusions, only 56 of these were treated by means of nephrectomy. Reimplantation 56 Twenty-three patients (4.6%) died in the hospital or within 30 Thromboendarterectomy 267 days of renal reconstruction. Mortality varied significantly with Splanchnorenal bypass 13 the magnitude of procedure. Mortality after isolated renal artery Total nephrectomies 56 repair was substantially lower than mortality after combined aor- tic and bilateral renal artery repair (0.8% versus 6.9%). Moreover, Total kidneys operated on 776
  • 7. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 22 OPEN PROCEDURES FOR RENOVASCULAR DISEASE — 7 100 Table 3 Results of Operative Treatment of Atherosclerotic Renovascular Disease among 90 472 Surgical Survivors2 80 Result Rate (%) 70 Dialysis-Free Survival (%) Perioperative mortality 4.6 Hypertension response 60 Cured 12 Improved 73 50 Failed 15 Renal function response* 40 Improved 58 Unchanged 35 30 Worsened 7 20 *For 220 patients with preoperative serum creatinine concentrations ≥ 1.8 mg/dl; a significant change is defined as a ≥ 20% change in EGFR. 10 0 with preoperative ischemic nephropathy, 58% showed improve- 0 20 40 60 80 100 120 140 ments in renal function, including 30 patients removed from dialysis dependence [see Table 3]. In contrast to previous reports Follow-up (months) that suggested the existence of a lower limit of renal dysfunction EGFR EGFR EGFR beyond which recovery could not be observed, the percentage of Improved Unchanged Worsened patients who showed improvement rose with increasing preop- Figure 7 Illustrated are product-limit estimates of time to death erative serum creatinine concentration. Overall, 75% of dialysis- or dialysis, stratified according to postoperative renal function dependent patients were permanently removed from dialysis response for patients with a preoperative EGFR of 25 ml/min/m2. after renal artery repair. In addition, the site of disease and the The interaction between preoperative EGFR and renal function extent of repair were found to influence increases in the EGFR. response for dialysis-free survival was significant and independent.2 100 Although each subgroup of patients who underwent operation demonstrated some improvement in renal function, the greatest 90 incremental increase in the EGFR was observed in those who underwent bilateral renal reconstruction for significant bilateral 80 disease.3,7 RELATIONSHIP OF HYPERTENSION RESPONSE AND RENAL 70 Dialysis-Free Survival (%) FUNCTION RESPONSE TO DIALYSIS-FREE SURVIVAL 60 At a mean follow-up of 56 months, 171 patient deaths had occurred.When outcomes were considered in terms of the blood 50 pressure response to operative intervention, only hypertension cured was found to be significantly and independently associat- 40 ed with survival or dialysis dependence: patients whose hyper- tension was cured experienced improved dialysis-free survival 30 [see Figure 6]. In contrast, all outcome categories for the renal function response influenced both survival and eventual dialysis 20 dependence. Patients with improved renal function experienced a significant increase in dialysis-free survival [see Figure 7].2 For patients whose renal function remained unchanged after oper- 10 ation, however, the risk of eventual dialysis dependence and death was equivalent to that of patients whose renal function 0 worsened after surgery. Whereas renal function that is un- 0 20 40 60 80 100 120 140 160 changed after intervention is frequently described as “stabilized” N=472 N=376 N=271 N=184 N=113 N=67 N=30 N=8 or “preserved,” our experience suggests that patients with ische- Follow-up (months) mic nephropathy and atherosclerotic renovascular disease whose renal function is unchanged postoperatively remain at increased Cured Improved Failed risk for eventual dialysis dependence and death.Whether similar Figure 6 Illustrated are product-limit estimates of time to death associations exist for patients treated by means of catheter-based or dialysis, stratified according to blood pressure response to oper- methods is unknown, but the question certainly merits future ation for atherosclerotic renovascular disease.2 study.
  • 8. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 22 OPEN PROCEDURES FOR RENOVASCULAR DISEASE — 8 References 1. Dean RH, Benjamin ME, Hansen KJ: Surgical man- tion. J Vasc Surg 29:140, 1999 8. Benjamin ME, Dean RH: Techniques in renal agement of renovascular hypertension. Curr Probl artery reconstruction: part I. Ann Vasc Surg 5. Hansen KJ, Deitch JS, Oskin TC, et al: Renal artery Surg 34:209, 1997 10:306, 1996 repair: consequence of operative failures. Ann Surg 2. Cherr GS, Hansen KJ, Craven TE, et al: Surgical 227:678, 1998 9. Benjamin ME, Dean RH: Techniques in renal management of atherosclerotic renovascular disease. J Vasc Surg 35:236, 2002 6. Hansen KJ, Reavis SW, Dean RH: Duplex scanning artery reconstruction: part II. Ann Vasc Surg in renovascular disease. Geriatr Nephrol Urol 6:89, 10:409, 1996 3. Hansen KJ, Cherr GS, Craven TE, et al: Manage- ment of ischemic nephropathy: dialysis-free survival 1996 10. Hansen KJ,Wong JM: Aortorenal bypass for renovas- after surgical repair. J Vasc Surg 32:472, 2000 7. Dean RH,Tribble RW, Hansen KJ, et al: Evolution of cular hypertension in adults. Current Therapy in Vas- 4. Oskin TC, Hansen KJ, Deitch JS, et al: Chronic renal renal insufficiency in ischemic nephropathy. Ann cular Surgery, 4th ed. Ernst CB, Stanley JC, Eds. artery occlusion: nephrectomy versus revasculariza- Surg 213:446, 1991 Harcourt Health Sciences, St Louis, 2000, p 735 Recommended Reading Deitch JS, Hansen KJ, Craven TE, et al: Renal artery re- study. J Vasc Surg 36:443, 2002 sonography: main renal artery versus hilar analysis. J Vasc pair in African-Americans. J Vasc Surg 26:465, 1997 Hansen KJ, Tribble RW, Reavis SW, et al: Renal duplex Surg 32:462, 2000 Edwards MS, Hansen KJ, Craven TE, et al: Relationships sonography: evaluation of clinical utility. J Vasc Surg between renovascular disease, blood pressure, and renal 12:227, 1990 function in the elderly: a population-based study. Am J Hunt JC, Strong CG: Renovascular hypertension: mecha- Kidney Dis 41:990, 2003 nisms, natural history and treatment. Am J Cardiol Acknowledgment Hansen KJ, Edwards MS, Craven TE, et al: Prevalence of 32:562, 1973 renovascular disease in the elderly: a population-based Motew SJ, Cherr GS, Craven TE, et al: Renal duplex Figures 1 through 4 Alice Y. Chen.