Renovascular Disease

Although the true incidence of renovascular hypertension is unknown, it is estimated that between 5% and 10% of all hypertensive patients suffer from renovascular hypertension.4 During the past two decades, there have been dramatic changes in the diagnosis and treatment of renovascular hypertension. There is clearly a better understanding of the renin–angiotensin system, and newer, more potent antihypertensive medications are available. In addition, newer diagnostic radiologic procedures, such as digital subtraction angiography, captopril renal scans, balloon angioplasty, and newer surgical techniques, have dramatically changed the ways in which we diagnose and treat renovascular hypertension today.
DIAGNOSIS
In the past, the clinician’s task of identifying potentially curable patients in a safe, cost-effective, and reliable manner was difficult. Recently we have been given the means to reliably identify patients with a physiologically significant renal artery stenosis that, in the past, might have eluded the physician. A single-dose captopril test is reported by some investigators to be a reliable screening test and is well suited for outpatient use. Although it is less reliable in patients with a degree of renal insufficiency, the peripheral plasma renin response to a single dose of oral captopril has proved to be a simple and sensitive test.7 In patients with a functional renal artery stenosis, ACE inhibitors lead to a disproportionate increase in peripheral plasma renin activity as a result of the disappearance of the inhibitory effect of angiotensin II on renin secretion. This phenomenon can be used diagnostically to detect unilateral renal artery stenosis. In cases of bilateral stenosis, however, the test cannot be used reliably as an indicator of renal artery stenosis.1 However, Postma et al.8 have reported that the captopril test is not a reliable screening test, and as a consequence, the value of this procedure as a screening test in detection of renal artery disease is at present unsettled.
Another test that has recently been analyzed for the detection of renal artery stenosis is the renal scintigram with isotopic nephrography following the administration of captopril.9 In a functional renal artery stenosis when ACE is inhibited, the glomerular infiltration rate decreases as a consequence of the decreased inhibition of angiotensin II on the vasa efferens. This can be demonstrated by technetium DTPA scintography. The sensitivity of this means of identifying renal artery stenosis varies from 71% to 92% with a specificity of 72% to 97%. In the hipuran scintigram, the patient with renal artery stenosis showed a continual enrichment of the isotope in the renal cortex, probably related to a decreased excretion of hipuran because of the ACE inhibitor.
Digital venous subtraction angiography (DSA), in my opinion, remains the most definitive and reliable screening test available. It has a sensitivity and specificity of nearly 90%. Intravenous DSA is susceptible to artifacts such as crossing vessels and from intestinal motility. In these patients, digital arterial subtraction angiography achieves an excellent view of the renal circulation using less contrast dye than conventional angiography. Because this method uses a comparatively small 4- to 5-Fr catheter, groin hematoma is rare, and the technique can be used in an outpatient setting.
Several other new modalities have appeared recently. Duplex Doppler ultrasound scanning is now a recognized way of demonstrating and locating focal renal artery stenosis. This noninvasive test is gaining acceptance in the diagnosis of both atherosclerosis and fi-bromuscular hyperplasia. In a recent study, Ferdinandi et al.3 report the ability to detect renal artery stenosis with a success rate of over 90%. Further studies will be necessary to determine the ultimate role of duplex sonography and color Doppler evaluation of renal ar-tery stenosis.
At present, digital subtraction angiography in conjunction with divided renal vein renin assays, which demonstrate contralateral suppression, remains the best screening test and predictor of treatment outcome.
In those patients who have azotemia, in whom contrast is contraindicated, MRI angiography and CO2 digital subtraction angiography are useful12 These studies avoid the use of contrast and obviate the occurrence of contrast toxicity.
INDICATIONS FOR SURGERY
The surgical management of renovascular hypertension has changed dramatically in the last two decades. In the early 1970s, we demonstrated that renal function could be preserved or restored by renal revascularization of nonfunctioning kidneys with totally occluded renal arteries. This contribution led to the notion that if patients who had totally occluded renal arteries and nonfunctioning kidneys could have restoration of renal function, then we could treat patients with renal artery stenosis who had azotemia with the expectation that they could also have preservation or improvement of renal function.5 Progressive azotemia in the elderly atherosclerotic patient population is now one of the indications for renal revascularization. Secondly, based on our observations, the use of alternative bypass procedures has significantly reduced the morbidity and mortality of high-risk patients undergoing renovascular surgery. The use of the hepatic artery, the gastroduodenal artery, and other alternative procedures instead of the aortorenal saphenous vein bypass graft has not only reduced the morbidity and mortality of surgery but, in doing so, has dramatically changed the nature of our patient population.
ALTERNATIVE THERAPY
Converting enzyme inhibitors prevent the conversion of angiotensin I to angiotensin II. These drugs in conjunction with calcium channel blockers have greatly improved the medical management of patients who suffer from renovascular hypertension. Unfortunately, even if adequate blood pressure control is maintained by pharmacologic means, progression of renal artery disease is not prevented, and renal ischemia and renal damage may clearly progress.11
When medical management fails or azotemia progresses, then balloon angioplasty and surgical treatment must be considered. The choice between angioplasty and surgery relies on a well-defined set of criteria established by published results. Angioplasty is indicated in the treatment of fibrous dysplasia and atherosclerosis of the mid–main renal artery. Surgery is indicated for the treatment of osteal atherosclerosis and for branch lesions of the renal artery. Renal artery aneurysms are a different problem. Surgery is indicated when they are the cause of hypertension. Also aneurysms larger than 2 cm in diameter that are noncalcified, especially in gestational women, should be repaired, as they are prone to rupture during pregnancy.
It is our feeling that patients who develop recurrent disease following balloon angioplasty are probably best subjected to surgical management, as repeat balloon angioplasty is associated with a significant complication rate. Use of the thoracic aorta may also be a viable alternative on the left side because the thoracic aorta is usually less atherosclerotic than the abdominal aorta.6
SURGICAL TECHNIQUES
Aortorenal Bypass Graft

The widespread popularity of the bypass graft for renal artery disease was attained by virtue of its technical ease of insertion and the favorable short- and long-term patency rates achieved. Bypass grafts are applicable to almost any disease process involving the main renal artery or its branches. This procedure also eliminates the more hazardous and tedious dissection of the juxtrarenal portion of the aorta required in endarterectomy. Bypass grafts are particularly suitable for fibrous lesions that affect long and multiple segments of the renal artery and its branches (Fig. 10-1). Dacron, autogenous artery (hypogastric and splenic), and autogenous saphenous vein may be chosen as aortorenal bypass grafts in properly selected patients.
Dacron has been applied extensively in renal artery reconstruction but has been associated with a relatively high rate of early thrombosis. Excellent long-term patency rates have been reported with a segment of autogenous hypogastric artery. Such a graft matches the size of the renal artery and is sutured more simply than the Dacron prosthesis.
Autogenous hypogastric artery is the most favorable graft material for children with renal artery disease because the saphenous vein is usually too small and is more prone to aneurysmal dilation than in adults. The major disadvantage is that the hypogastric artery is often the first to be involved with generalized atherosclerosis and therefore is not suitable graft material in older patients. It is also a short vessel and occasionally is technically more difficult to insert between the renal arteries and aorta.
During the past two decades the autologous saphenous vein has emerged as our preferred graft material and is the most common source for restoration of renal blood flow at our hospital. Saphenous vein is readily available and closer in size to the lumen of the renal artery than other vascular conduits. Its intima is less thrombogenic than prosthetic material and accommodates the creation of a precise contoured anastomosis with a delicate thin-walled distal renal artery. Patent anastomoses can be achieved with the most challenging 2- to 3-mm-lumen branches beyond the major bifurcation. Because of its inherent properties and the favorable surgical results obtained, saphenous vein has become the conduit of choice for aortorenal bypass at most major renovascular centers. If the saphenous veins are not available, we use cephalic vein and Gore-Tex graft, in that order, as substitutes.
Procurement of Saphenous Vein
The procurement of an adequate segment of the long saphenous vein is critical to the success of the graft procedure. Meticulous technique in exposure and excision of the vein is essential to prevent mural trauma and ischemia. Improper harvesting of the vein may result in the delayed complications of stenosing intimal hyperplasia and aneurysmal dilation. Removal of the saphenous vein should be performed by an experienced surgeon.
The saphenous vein is usually obtained from the thigh opposite the renal lesion so that two surgeons may simultaneously expose the renal vessels and mobilize the graft, shortening the operative time. The vein is mobilized through a single long incision in the upper thigh (Fig. 10-2), which begins parallel to and below the groin crease over the palpable femoral pulses and is extended toward the knee after the junction of the saphenous and femoral veins has been exposed. The incision should be made directly over the vein to avoid producing devascularized skin flaps that can result in necrotic edges and wound sepsis. Finger dissection between the trunk of the vein and the skin is helpful to ensure accurate placement of the incision and, thus, to avoid development of these flaps (see Fig. 10-2). On the day before operation, the course of the saphenous vein is outlined with an indelible pen while the patient is standing.
A 20-cm-long vein graft with an outside diameter of 4 to 6 mm is usually adequate for reconstruction of the renal artery. Excess vein should always be available for revision of any intraoperative technical problems that may occur during anastomosis. The vein is handled gently without stretching or tearing its branches. The tributaries are tied in continuity with fine silk before they are divided. The areolar tissue is dissected from the specimen, and the adventitia is left undisturbed.
To decrease transmural ischemia, the vein graft remains4 in situ until the renal vessels are mobilized and it is ready to be used. If the graft is inadvertently removed prematurely, it is placed in cold Ringer’s lactate solution or autologous blood, even if only a short period of time will ensue. The distal end of the vein is transected, cannulated with a Marks needle, and secured with a silk tie (Fig. 10-3). A dilute heparinized solution of autologous blood distends the vein graft before the proximal is transected. This step helps to identify any untied tributaries or unrecognized leakage and washes out any residual blood clots. The vein is distended to a minimal diameter of 5 to 6 mm by exerting gentle pressure on the syringe. The proximal end of the vein is transected, and the vein graft is now ready for use. The thigh incision is not closed until the bypass procedure has been completed to ensure that any delayed bleeding caused by the heparinized state is identified and controlled.
Technique of Insertion of Saphenous Vein Graft
Heparin is initially given systemically after the surgical dissection has been completed and approximately 30 minutes before the arteries are clamped. The saphenous vein graft should be oriented properly to avoid misalignment during implantation. Either an end-to-end or an end-to-side anastomosis can be accomplished, depending on the anatomic situation encountered. An end-to-end anastomosis is preferred under usual circumstances because it permits the best laminar flow.
The aorta, which has already been mobilized and exposed from the renal arteries to the level of the inferior mesenteric artery, is carefully palpated to determine a suitable soft location for the anastomosis that is relatively free of atherosclerotic plaque. A medium-sized DeBakey clamp is placed on the anterolateral portion of the infrarenal aorta in a tangential manner. A vertical 13- to 16-mm aortotomy is made without excising any of the aortic wall or attempting to perform a localized endarterectomy (Fig. 10-4), which may dislodge intimal plaque fragments that can form emboli to the lower extremities when the clamp is released.
Excision of the aortic wall is not necessary because intraluminal aortic pressure spreads the edge of the linear aortotomy to the appropriate dimensions when the clamp is released. The vein graft is anastomosed to the aorta with continuous 5-0 Proline suture after it has been satisfactorily spatulated (Fig. 10-5). A microvascular Schwartz clamp is placed on the end of the saphenous vein graft, and the aortic clamp is released. The graft is allowed to lie anterior to the vena cava on the right side or anterior to the renal vein on the left side. Although it is preferable to leave the vein too long than too short, it should not be so long as to bend into an acute angle at any point. The renal artery is secured distally with a smooth-jawed Schwartz microvascular clamp placed on either the distal main renal artery or its branches. The proper site for the arterial anastomosis is selected. An end-to-end anastomosis is performed utilizing a continuous 6-0 Proline suture or interrupted sutures of the same material, depending on the diameter of the anastomosis (Fig. 10-6). When the saphenous vein graft is being anastomosed with two branches 3 mm or less in size, interrupted sutures are chosen. An interrupted suture line is also selected in children to prevent a pursestring effect with growth of the vessels when the patients become older. This effect may also occur with running synthetic monofilament sutures when too much tension is applied during the creation of the anastomosis. The pursestring effect can be avoided by placing sutures at four quadrants in the arterial wall before beginning the anastomosis. Operating loupe magnification and fiberoptic headlamps are very helpful at this point in the operation to allow precise placement of the sutures, particularly when exposure in the renal artery is difficult.
Alternative Arterial Bypass Grafts
Extensive atherosclerosis, previous aortic surgery, and complete thrombosis of the aorta may preclude the use of the aortorenal bypass procedure for renal artery reconstruction. When the surgeon is treating a patient with stenosis of the right renal artery in association with these pathologic limitations on the aorta, a splenorenal or hepatic-to-renal artery saphenous vein bypass or gastroduodenal-to-renal artery bypass procedure can be selected.
Splenorenal Arterial Bypass
Splenorenal arterial bypass has many desirable features as a substitute for aortorenal bypass in patients with stenosis of the left renal artery. It is particularly suitable for patients who have diffuse atherosclerotic disease or thrombosis of the aortic lumen and for those who have previously undergone difficult aortic reconstructions.
The splenic artery has the advantages of being an autogenous artery that has not been separated from its nutrient vaso vasorum, of being exposed without difficulty by a relatively uncomplicated anatomic dissection, and of requiring only one vascular anastomosis. Carefully monitored oblique and lateral angiography of the celiac axis is required to determine the patency of this artery because atherosclerosis can affect the arterial lumen early in the patient’s life. Surgical exploration and intraoperative evaluation by palpation and measurement of splenic blood flow are also helpful in establishing its suitability for renal revascularization. If the blood flow is less than 125 ml/min, the splenic artery should probably not be utilized for renal artery bypass.
We now prefer to expose the splenic artery through a supracostal 11th-rib flank incision (Fig. 10-8). The dissection is continued along the upper border of the rib. The overlying latissimus dorsi, the serratus posterior inferior, and the intercostal muscles are divided. Division of the intercostal ligament permits the rib to move freely. The external, internal oblique, and transversus abdominis muscles are divided, and the intercostal muscle attachments on the distal 1 inch of the rib are divided carefully until the corresponding intercostal nerve is identified. The investing fascia around the nerve is entered. Dissection in this plane allows an extrapleural approach and generally avoids entry into the pleural cavity. This approach also allows excellent exposure, for the ribs are free to pivot downward in a “bucket-handle” fashion (Fig. 10-9).
The plane between Gerota’s fascia and the adrenal gland posteriorly and the pancreas anteriorly is entered. The splenic artery is identified at the upper border of the pancreas. Its enveloping fascia is entered, and the splenic artery is mobilized by a purely retroperitoneal approach. Several small pancreatic branches are identified, isolated, ligated, and divided. The splenic artery can usually be mobilized from the splenic hilum to the celiac axis without difficulty, and it provides sufficient length to reach the left renal artery.
After the splenic artery is mobilized, a sponge soaked with papaverine is placed on it to permit it to dilate. The artery is divided just proximal to its primary bifurcation in the hilum of the spleen, after a suitable vascular clamp has been applied to the origin of the artery. If necessary, the artery may be dilated with a Gruntzig balloon or Fogarty catheter intraoperatively to obtain maximum caliber. Removal of the spleen is not necessary because it continues to receive adequate blood flow from the short gastric arteries. The left kidney is approached posteriorly, and the left renal artery is identified and mobilized (Fig. 10-10). The renal artery is ligated at the aorta, and an end-to-end anastomosis between the splenic artery and the distal renal artery is carried out using continuous or interrupted 6-0 Proline sutures (Fig. 10-10). We have employed this approach in nearly 100 patients and now prefer it to the traditional transabdominal technique.

Splenic artery disease, the risk of pancreatitis, and the formation of a pancreatic pseudocyst are some of the limitations that have restricted splenorenal bypass as a routine procedure in the management of disease of the left renal artery.
Hepatorenal Bypass Graft
Arising from the celiac axis and continuing along the upper border of the pancreas, the hepatic artery reaches the portal vein and divides into an ascending and a descending limb. The ascending limb is a continuation of the main hepatic artery upward within the lesser omentum; it lies in front of the portal vein and to the left of the biliary tree. The descending limb forms the gastroduodenal artery. In the porta hepatis, the hepatic artery ends by dividing into the right and left hepatic branches, which supply the corresponding lobes of the liver (Fig. 10-12). The anatomic variations in the hepatic circulation must be appreciated before this procedure can be utilized. The right hepatic artery is more variable than the left. It may be anterior (24% of patients) or posterior (64% of patients) to the common bile duct, and in 12%, this artery arises from the superior mesenteric artery (Fig. 10-13). The hepatic artery lies anterior (91% of patients) or posterior (9% of patients) to the portal vein. In addition, the left hepatic artery arises from the left gastric artery in 11.5% of patients.
Careful dissection of the porta hepatis is essential, and the common hepatic, gastroduodenal, and right and left hepatic arteries should be identified before an anastomotic procedure is attempted. Vascular elastic loops are placed about these vessels, and the common bile duct and portal vein are identified.
After careful dissection and mobilization of the renal artery, clamps are placed on the proximal portion of the common hepatic artery and its distal branches. The gastroduodenal artery is divided (Fig. 10-14). The inferior surface of the hepatic artery is mobilized from the underlying portal vein and the common bile duct. An arteriotomy, 10 to 12 mm in length, is made in the anterior inferior wall of the common hepatic artery, beginning at the ostium of the gastroduodenal artery. A reversed autogenous saphenous vein is inserted with an end-to-side anastomosis between the vein graft and the hepatic artery. This maneuver is usually accomplished with a continuous 6-0 Proline suture. A microvascular clamp is placed on the vein graft after it has been filled with heparin and after the proper alignment and length for the renal artery anastomosis has been determined. The clamps are removed from the hepatic circulation, and a small Schwartz microvascular clamp is placed on the distal renal artery. The vein graft is anastomosed to the right renal artery in an end-to-end fashion. When the gastroduodenal artery is used, it is divided, and an end-to-end anastomosis between the gastroduodenal artery and the renal artery is accomplished.
We have employed this procedure in approximately 50 patients with good results. Postoperative angiography has demonstrated the absence of a renal–hepatic steal syndrome. Liver function has not been compromised in any of our patients to date. We no longer advocate the use of the gastroduodenal artery in adult patients, but it is a perfectly acceptable bypass procedure in the pediatric patients.
We have also utilized the superior mesenteric-to-renal artery saphenous vein bypass as a “bailout procedure” as well with good results (Fig. 10-15). An iliac-to-renal bypass graft has been done as an alternative to the aortorenal bypass procedure in ten of our patients, with favorable results (Fig. 10-16).
Renal Autotransplantation and Ex Vivo Bench Surgery
On rare occasions, kidneys with lesions of the renal artery or its branches are not amenable to in situ reconstruction. In these circumstances, temporary removal of the kidney, ex vivo preservation, microvascular repair (bench surgery), and autotransplantation may permit salvage.
Autotransplantation developed as an outgrowth of the technique in renal transplantation. The simultaneous development of an apparatus that could preserve kidneys extracorporeally for long periods of time and of preservation solutions also led to the technique of extracorporeal renal repair.
Autotransplantation and ex vivo repair should be considered in patients with traumatic arterial injuries, when disease of the major vessels extends beyond the bifurcation of the main renal artery into the segmental branches, and when multiple vessels supplying the affected kidney are involved. Bench surgery may also be required in patients who have very large aneurysms, arteriovenous fistulas, or malformations (Fig. 10-17).
Other indications for autotransplantation that usually do not require ex vivo repair include abdominal aortic aneurysms that involve the origin of the renal arteries and extensive atheromatous aortic disease, when an operation on the aorta itself may prove hazardous. In the last case, the patients usually have extensive internal iliac artery disease that precludes utilization of this artery for autotransplantation. However, we have noted that in these instances, the external iliac artery is spared extensive atherosclerosis and is suitable for autotransplantation, with an end-to-side renal artery anastomosis or an iliac-to-renal bypass graft.
Techniques for Autotransplantation
Autotransplantation can be accomplished through a large single midline incision or two separate flank and iliac fossa incisions. When the kidney is removed, care is taken to preserve the maximum length of renal vessels and ureter. If the transabdominal approach is selected, ureteral continuity can be retained, necessitating only vascular anastomosis afer the kidney is flipped over. If ex vivo surgery requires transection of the ureter, ureteroneocystostomy is necessary in addition to vascular anastomosis.
When ureteral continuity is preserved, autotransplantation is performed as illustrated in Fig. 10-18. When the kidney has been excised completely, the standard techniques for renal homotransplantation are used.
During dissection of the iliac vessels, meticulous care is taken to ligate the lymphatics in this area to prevent the development of a lymphocele. The external iliac vein is freed to the point where it is crossed by the internal iliac artery (Fig. 10-19A). The renal vein is anastomosed end-to-side to the external iliac vein using 5-0 Proline sutures (Fig. 10-19B). If the renal artery is free of atherosclerotic disease, it is then anastomosed end-to-end to the internal iliac artery, employing 6-0 Proline sutures (Fig. 10-19C,D). If the internal iliac artery is diseased, the renal artery is anastomosed end-to-side to the external iliac artery.
When the ureter requires reimplantation, we prefer a modification of the Politano–Leadbetter ureteroneocystostomy. Saline solution, 2 to 3 ml, is injected submucosally, raising a mucosal bleb (Fig. 10-20A). A small segment of mucosa is removed from the inferior portion of the bleb (Fig. 10-20B). A right-angle clamp is inserted into this opening, and a 3-cm-long submucosal tunnel is created (Fig. 10-21A). At the apex of the tunnel, the right-angle clamp is rotated 180 degrees to pierce the detrusor muscle. The ureter is brought to lie in the submucosal tunnel (Fig. 10-21B). The distal ureter is cut at a 45-degree angle, and the ureter is anastomosed to the bladder with interrupted 4-0 or 5-0 Dexon or Vicryl sutures (Fig. 10-21C,D).
In the future, the use of endovascular prostheses in maintaining the effect of luminal balloon dilatation is a very promising technique if long-term evaluation confirms the preliminary results.
OUTCOMES
Complications

Complications of renal vascular surgery can be classified as early or delayed. Early complications include bleeding, thrombosis of the artery, embolization of the branch vessels, subintimal dissection, false aneurysms, and loss of the kidney. Postoperative bleeding requiring operative intervention is to some extent a technical failure but may also be a function of the structural integrity of the arterial wall in diseased segments. It is important to recognize the enlarged perihilar vessels that are seen in high-grade stenosis and to be cognizant of the adrenal venous channels. Delayed bleeding may be the result of false aneurysm formation or erosion of the graft anastomosis into the duodenum or other bowel.
Renal artery thrombosis is the most common complication of renal vascular reconstruction and is most common after either placement of a dacron graft or endarterectomy. Predisposing factors include small dacron grafts, renal atrophy associated with thin-walled diseased arteries and high intrarenal vascular resistance, hypotension, or hypovolemia. It has been shown that the thrombosis of both venous and synthetic grafts is partially affected by the adequacy of the peripheral runoff as well as the adequacy of resection of the endothelial plaques in atheroschlerotic vessels. Embolization of plaque to the distal extremities or aortic thrombosis is rare.
Results
Balloon angioplasty is primarily used to treat patients with mural dysplasia.2,10 This modality of treatment is 80% to 85% effective in the management of these patients at our institution. Balloon angioplasty has a very limited role in the management of atherosclerotic renovascular disease at our institution.
The combination of balloon angioplasty for the younger, healthier patients suffering from mural dysplasia, the advent of alternative bypass procedures, and the concept of revascularization for preservation and restoration of renal function have dramatically changed the nature of the patient population being referred to our institution for renal revascularization. We are now frequently being called on to revascularize more elderly, higher-risk patients with diffuse atherosclerosis who have failed aggressive antihypertensive therapy in order to improve their renal function. We have recently reported a series of more than 100 patients who have undergone renal revascularization for preservation and restoration of renal function with an 85% success rate in this very high-risk patient population.5
CONCLUSION
Renovascular disease is a rapidly changing clinical entity. Considerable progress is being made in screening and diagnosis, primarily as a result of the development of less- or noninvasive studies. Renovascular disease is a potentially curable cause of hypertension and one of the few curable or preventable causes of renal failure. The indications for angioplasty and surgical revascularization are better known, and interventional therapy is justified when anesthesia and surgery represent an acceptable risk. We look forward to the short- and long-term results of renal artery atherectomy and wall stenting with anticipation.

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