Results of surgery in fibrodysplastic renal artery stenosis

At the University of Essen Hospital, 202 patients underwent operations for renovascular hypertension between September, 1971, and August, 1979. In 75 (37.2%) of the patients (64 female and 11 male, ages 8–55 years), a fibrodysplastic stenosis of one or both renal arteries was found. These patients were treated after angiographic demonstration of a renal artery stenosis, with no further functional testing, e.g., renal vein renin ratio or Saralasin test. Operative procedures included resection of the stenosis and reanastomosis in 45, vein patch angioplasty in 13, vein graft reconstruction in 11, and reimplantation of the renal artery into the aorta in 6 patients. In 5 patients (6.7%) a nephrectomy was necessary because of artery thrombosis. There were no operative deaths. Ninety-six percent of the patients showed a normal or improved blood pressure in the immediate postoperative course. In more than 85% of the patients, reinvestigated 2, 4, and 6 years after the operation, hypertension was cured or improved. We conclude that surgical treatment of renal artery stenosis of flbrodysplastic origin is indicated without further functional tests.     

Renal vein renin: value and limitations in the prediction of operative results.

Renal vein renin determinations, in contrast to isolated peripheral venous renin determinations, provide great help in the selection of patients who can benefit from an operation for renal hypertension. Patients with essential hypertension usually have renal vein renin ratios, larger/smaller, close to unity, but the available cumulative data show that, statistically, ratios as large as 2.0 may occur in this group (95 per cent confidence limits). In patients with unilateral stenosis of a main renal artery, large renal vein renin ratios (stenotic/normal) have been followed by operative success in more than 90 per cent of patients. However, many operative successes have also been achieved in patients without a large renal vein renin ratio. This may be explained by inaccurate renal vein catheterization, inactive renin secretion, nonsimultaneous sampling, assay variability, and problems related to bilateral or segmental lesions. Recent refinements in the interpretation of renal vein renin data (contralateral suppression, ipsilateral hypersecretion in absolute terms, and a combination analysis scoring system) appear to increase the accuracy of the test. Detailed anatomic information, provided by arteriography, is essential for proper interpretation of renal vein renin data.     

Renovascular hypertension: does the renal vein renin ratio predict operative results?

Renal vein renin ratios from 56 hypertensive patients who were operated upon for unilateral stenosis of a main renal artery were compared to blood pressure response to a corrective operation. In patients with renal vein renin ratios greater then 2.0, the upper limits of normal for essential hypertension (95 per cent confidence limits), the cure/improvement rate approximated 90 per cent. However, in patients operated upon despite lesser ratios the cure/improvement rate was also high--83 per cent in our series and 57 per cent in collected reports from the literature. Thus, the test may be falsely negative in a high percentage of patients. Renal vein renin ratios would appear to be most useful in confirming but not necessarily in denying the functional significance of a renal artery stenosis.     

Renal tuberculosis and hypertension: value of the renal vein renin ratio

We applied the central renal vein renin ratios in a group of patients with unilateral renal tuberculosis and hypertension to see whether the diseased kidney was involved in the pathogenesis of the elevated blood pressure. Of 20 patients 11 were nephrectomized, 7 had positive renal vein renin ratios and normal peripheral plasma renin activity; only 2 kept their blood pressure in control without medication. From 5 without a positive index, only 1 kept his blood pressure in control without medicine 1 year after surgery. The renal vein renin ratio has to be interpreted in light of other parameters, such as blood pressure, peripheral renin--if high the more the chance of being significant--and global renal function. The renal vein renin ratio alone per se gives poor information on the pressor role of a unilateral tuberculous kidney.     

Divided renal and caval vein plasma renin activity in two-kidney two-clip hypertension in rabbits and variations of blood pressure, plasma volume and renal function following unilateral nephrectomy

Determinations were made of peripheral plasma renin activity, blood pressure, plasma volume and blood urea nitrogen in rabbit models of two-kidney one-clip, two-kidney two-clip or one-kidney one-clip hypertension that were created by staged operation to produce functionally significant renal artery stenosis. The plasma renin activity in the divided renal veins and inferior caval vein was also measured in animals with two-kidney two-clip hypertension. In rabbits with two-kidney two-clip hypertension the plasma renin activity was significantly higher in the renal vein on the more involved side and comparable in the renal vein on the less involved side and the inferior caval vein. This response pattern of renin secretion, unilateral hypersecretion with contralateral suppression, was identical with that observed in animals with two-kidney one-clip hypertension. In animals with one-kidney one-clip hypertension there was a marked increase in plasma volume and blood urea nitrogen. The renovascular hypertension was in decreasing order of severity in animals with one-kidney one-clip hypertension, those with two-kidney two-clip hypertension and those with two-kidney one-clip hypertension.     

Renal Artery Stenosis: To Intervene,or Not to Intervene, “That is the Question”

Renal artery stenosis (RAS) due to atherosclerosis continues to be a major cause of secondary hypertension. It can also lead to renal dysfunction due to ischemic nephropathy. While major clinical trials have emphasized that medical management should be preferred over angioplasty and stenting for the treatment of renal artery stenosis, clinical scenarios continue to raise doubts about the optimal management strategy. Herein, we present two cases that were admitted with hypertensive emergency and renal function deterioration. Medical therapy failed to control the blood pressure and in one patient, renal failure progressed to a point where renal replacement therapy was required. Both patients underwent angioplasty (for >90% stenosis) and stent insertion with successful resolution of stenosis by interventional radiology. Postoperatively, blood pressure gradually decreased with improvement in serum creatinine. Dialysis therapy was discontinued. At 4‐ and 8‐month follow‐up, both patients continue to do well with blood pressure readings in the 132–145/70–90 mmHg range. This article highlights the importance of percutaneous interventions in the management of atherosclerotic RAS and calls for heightened awareness and careful identification of candidates who would benefit from angioplasty and stent insertion.     

Renal artery stenosis and nephrotic syndrome: a rare combination in an infant

We describe an uncommon pediatric finding of unilateral renal artery stenosis, which presented as nephrotic syndrome, hypertension, failure to thrive, and hyponatremia. The child was a previously well 8-month-old male who looked well but had mild periorbital edema with severe hypertension. After 3 days of captopril therapy, the nephrotic-range proteinuria significantly improved. However, the hypertension persisted. Renal imaging revealed a small left kidney with reduced parenchymal uptake and no significant excretion. A renal angiogram demonstrated left renal artery stenosis with increased left renal vein renin activity. The hypertension resolved within 24 h of a left nephrectomy, but non-nephrotic-range proteinuria persisted for 8 months post operatively. Pathology of the left kidney was consistent with fibromuscular dysplasia. Although a few glomeruli (1%) had changes consistent with focal segmental glomerulosclerosis, such a few abnormal glomeruli were unlikely to account for the nephrotic syndrome. Hypertension-induced changes in the unaffected right kidney probably caused the nephrotic-range proteinuria.     

False-negative saralasin responses in renovascular hypertension.

Blood pressure responses to the infusion of saralasin and plasma renin levels were measured in 31 hypertensive patients following preparation with frusemide. Five patients had unilateral renal artery stenosis, with renal vein ratios lateralising strongly to the affected side. Saralasin produced depressor responses in 3 of these but failed to evoke significant effects in the other 2, despite the fact that in both cases hypertension was subsequently alleviated by renal bypass surgery. A further period of more severe sodium depletion increased plasma renin levels and the depressor effect of saralasin, but did not help to differentiate renal artery stenosis from other forms of hypertension.     

Plasma renin activity revealed renal artery stenosis concealed by aneurysms

We describe a case of renovascular hypertension with renal artery stenosis concealed by aneurysms. Arteriography demonstrated no apparent renal artery stenosis, but did reveal aneurysms on the left renal artery. Captopril-loaded renoscintigraphy could not detect disturbed renal perfusion. High basal and exaggerated plasma renin activity after captopril administration were the only clues indicating renovascular hypertension. A reduction of the systemic blood pressure and normalized plasma renin activity after resection of the aneurysms confirmed preoperative renovascular hypertension. Fibromuscular dysplasia was an underlying cause of the arterial deformity. In cases of hypertension accompanied by renal artery aneurysms, the captopril-challenge test can be a useful tool to detect renal artery stenosis concealed by the aneurysms.     

Early diagnosis and management of renovascular hypertension

Renovascular hypertension is more common in hypertensive children than in hypertensive adults, and renal artery stenosis is second only to coarctation of the thoracic aorta as a cause of surgically correctable hypertension. Three infants presented with uncontrollable hypertension secondary to renal artery thrombosis due to umbilical artery catheterization for respiratory distress in the neonatal period. They all responded to nephrectomy. A fourth infant had stenosis of a polar vessel secondary to umbilical artery catheterization and was cured by partial nephrectomy. Two infants with renal artery stenosis secondary to fibromuscular dysplasia benefited from revascularization and, at last follow-up, were normotensive and off all blood pressure medication. Ultrasonography, isotope scanning, angiography and selective renal vein renin assays should be used to identify patients with surgically correctable lesions. The use of fine suture material and microvascular surgical techniques, including ex vivo revascularization and autotransplantation, can salvage renal parenchyma and relieve hypertension. Infants with less than 10 percent renal function on the involved side should have a nephrectomy. The infant with an umbilical arterial catheterization line needs blood pressure monitoring and aggressive evaluation and treatment of persistent hypertension.     

Coarctation of the abdominal aorta: current options in surgical management.

Coarctation or hypoplasia of the abdominal aorta is a rare cause of life-threatening hypertension. In most cases the mechanism of hypertension is elevated blood renin levels secondary to associated renal artery stenosis. Medical control of the hypertension is often difficult, and thus patients usually require renal artery revascularization combined with aortic bypass or replacement early in life. Current surgical management should optimize the use of autogenous methods of renal artery reconstruction including saphenous vein aortorenal bypass, splenorenal arterial anastomosis, hepatorenal saphenous vein bypass, and renal autotransplantation. In selected patients the reconstruction can be staged by correction of the renal artery stenosis and postponement of definitive repair of the aortic coarctation until it becomes hemodynamically significant.     

Response to angiotensin inhibition in rats with sustained renovascular hypertension correlates with response to removing renal artery stenosis

Purpose: Sustained (late-phase) renovascular hypertension is associated with lower plasma renin activity than is the early phase. It is not clear to what extent this reduced plasma renin activity reflects diminished influence of the renin-angiotensin system. It also is not clear whether this change in the character of the disease influences the effectiveness of surgical removal of the renal artery stenosis in reversing hypertension. Using an animal model of sustained (≥10 weeks after renal artery clipping) two-kidney, one-clip renovascular hypertension, we hypothesized that the magnitude of the depressor response to selective angiotensin II receptor blockade with losartan would reflect the influence of the renin-angiotensin system on hypertension and enable us to predict the depressor response to subsequent surgical removal of the clip. Methods: The left renal arteries of 20 male Sprague-Dawley rats weighing 150 to 200 gm were fitted with a silver clip (0.23 mm internal diameter). Systolic blood pressure was measured by means of tail-cuff plethysmography for 10 weeks. Rats were then given losartan orally (30 mg/kg a day) for 1 week while blood pressure was monitored. After an additional week to allow recovery, 13 rats underwent surgical unclipping, and seven underwent sham repair. Blood pressure again was monitored over the final week. Results: All two-kidney one-clip rats had hypertension 10 weeks after clipping (mean systolic blood pressure 206 ± 10 mm Hg). Losartan decreased systolic blood pressure by 36 ± 6 mm Hg. The response was variable, ranging from 3 to 66 mm Hg, and overall blood pressure did not normalize (170 ± 8 mm Hg). Subsequent surgical unclipping decreased systolic blood pressure by 46 ± 9 mm Hg. Again the response was variable, ranging from 10 to 99 mm Hg, although overall blood pressure did not normalize (164 ± 7 mm Hg). The decrease in blood pressure after unclipping showed a high correlation with the blood pressure decrease after losartan administration (r = 0.861, p < 0.001). Resting plasma renin activity (before intervention) was 16 ± 4 ng angiotensin I per milliliter per hour and was not predictive of the response to either losartan or surgical unclipping. The rats subjected to sham operations had no statistically significant changes in blood pressure. Histologic evaluation showed patent renal arteries without appreciable stenosis or intimal hyperplasia after removal of the clips. Conclusions: In sustained two-kidney, one-clip renovascular hypertension, the depressor response to angiotensin II receptor blockade is attenuated, suggesting that late-phase hypertension becomes increasingly angiotensin II-independent. In our model, the extent to which sustained renovascular hypertension becomes refractory to 7 days of angiotensin II blockade is highly predictive of the ultimate outcome of surgical repair of renal artery stenosis. (J Vasc Surg 1998;28:167-77.)     

Efficacy and safety of Palmaz stent insertion in the treatment of renal artery stenosis in kidney transplantation

Abstract The aim of this study was to verify the safety and long‐term efficacy of Palmaz stent insertion in the treatment of transplant renal artery stenosis (TRAS) in kidney transplantation. Nine of our transplanted patients were submitted to Palmaz stent insertion because of recurrence of renal artery stenosis after previous percutaneous transluminal angioplasty or because of severe ostial stenosis. The post‐stenting results were excellent in all patients, with a follow‐up period ranging from 1 to 3 years. The mean blood pressure (one‐third systolic pressure plus two‐thirds diastolic pressure) fell from 118.11 ± 7.44 to 103.21 ± 9.25 mm Hg; P < 0.001. Renal artery peak blood flow velocity as determined by Doppler sonography fell from 352 ± 73.24 cm/s to 169.8 ± 23.35 cm/s; P < 0.001. The serum creatinine 1‐year after stenting was 1.3 ± 0.3 mg/dl with a slight reduction with respect to the prestenting values (1.5 ± 0.3 mg/dl; NS). As no complication occurred, we conclude that insertion of the Palmaz stent is a safe and effective way to treat recurrence of artery stenosis or ostial stenosis in renal transplanted patients.     

Renal cell carcinoma and arterial hypertension

Background  The association between renal cell carcinoma and arterial hypertension has been the subject of various studies. These studies have not been consistent in clarifying the relationship between the two. Some authors contend that arterial hypertension is a consequence of renal cell carcinoma, which secretes vasoactive peptides. Others claim that arterial hypertension is a risk factor for the development of renal cell carcinoma. The purpose of our study is to assess if there is a direct connection between arterial hypertension and renal cell carcinoma. Methods  Out of 16,755 patients who were examined by ultrasonography, 40 were diagnosed with renal tumors. Of the 40 patients, 29 had malignant renal tumors, and 11 had benign renal tumors. These diagnoses were confirmed by CT scan, renal biopsy, and histology. Most of the patients with renal cell carcinoma (79.3%) had arterial hypertension. The group with benign renal tumors served as a control group. Out of the 29 patients with malignant renal cell carcinoma, 24 patients were treated with total nephrectomy, one had a partial nephrectomy, and four patients were too unwell for surgical intervention. In the group of those with benign renal tumors, seven patients had partial nephrectomies for the removal of angiomyolipomas. The personal histories were taken at the initiation of the study, and vital signs were obtained before and after surgery. Statistical analyses were performed using the Statistical Package for Social Sciences, version 10.0. Results  In the malignant group, the systolic blood pressure (SBP) before surgery was 157.41 ± 27.86 mmHg, and the diastolic blood pressure (DBP) was 97.24 ± 15.33 mmHg, while in the benign group, SBP was 134.55 ± 17.53 mmHg, and DBP was 88.18 ± 14.01 mmHg. In the malignant group in those who had undergone nephrectomies, the mean systolic pressure was 136.82, and the diastolic pressure was 85.90. In the benign group, the systolic and diastolic blood pressures were normal before and after surgery. Conclusion  In the group of patients with both renal cell carcinoma and arterial hypertension, their hypertension was resolved after they underwent nephrectomies. In conclusion, our data suggest that renal cell carcinomas may cause arterial hypertension.     

The Use of Drug‐Eluting Stents in the Management of Transplant Renal Artery Stenosis

Transplant renal artery stenosis (TRAS) is a common occurrence following kidney transplantation with an incidence rate ranging from 6% to 23%. A single‐center retrospective study was conducted to examine the use of drug‐eluting stents (DES) in eligible patients with hemodynamically significant TRAS. Between March 2008 and January 2011, 12 patients were diagnosed with TRAS with reference vessel diameter measuring <5 mm and underwent endovascular intervention (EVI) with DES placement. TRAS was detected within the first year posttransplantation in a majority of these patients (83%) and manifested as hypertension (100%), allograft dysfunction (100%) and edema (58%). Procedural success rate was 100%. Patients were followed for a mean period of 16 ± 10 months. Blood pressure improved from a mean of 156/82 to 138/73 mmHg at the end of the follow‐up period. In 11/12 patients, serum creatinine improved from 3.1 ± 1.3 mg/dL to 2.3 ± 0.5 mg/dL at the end of the follow‐up period. TRAS of early onset is readily amenable to EVI with stent placement resulting in improvement in blood pressure control and allograft function.     

Severe hypertension and massive proteinuria in a newborn with renal artery stenosis

Renal vein thrombosis and the congenital nephrotic syndrome have been associated with nephrotic-range proteinuria/nephrotic syndrome and hypertension in the newborn period. We describe a newborn with severe hypertension and proteinuria secondary to unilateral renal artery stenosis. Proteinuria completely disappeared with blood pressure control (with sodium nitroprusside and an angiotensin-converting enzyme inhibitor). Although renin was not measured, we speculate that proteinuria might have been induced by a high renin state, and was controlled by the angiotensin-converting enzyme inhibitor.     

Technical consideration in management of renovascular hypertension in an infant with double renal arteries

Renovascular hypertension is a curable disease that has recently been recognized with increasing frequency. A renal scan in a 1-month-old hypertensive white male showed diminished function of the right kidney, and his peripheral vein renin was elevated. Multiple antihypertensive medications failed to control his hypertension, and right kidney function deteriorated. An arteriogram showed two stenotic renal arteries supplying the right kidney. The smaller inferior artery supplied 35% of the kidney. Selective vein renin levels were greater than 15,000 ng/dL on the right side. Technical considerations in the repair of this lesion included midline transabdominal incision to expose the abdominal aorta and the inferior vena cava; dissection of inferior vena cava (IVC) with division of selected lumbar veins; full mobilization of right kidney and transsection of both renal arteries and the renal vein; perfusion of kidney via each renal artery with cold Sach's solution after resection of arterial stenoses; end-to-side microvascular anastomosis of the smaller (2 mm) renal artery to the main renal artery at the hilum with 10-0 nylon over in situ perfusion cannula; renal artery passed under the IVC to the aorta; and right kidney autotransplanted to a new site on the abdominal aorta with an end-to-side (5.0 mm) renal artery to the aorta and an end-to-side renal vein to IVC anastomosis. Following revascularization, perfusion was excellent and the blood pressure returned to normal. At 6 months follow-up, selective renal vein renins were normal and an arteriogram showed no stenosis. Meticulous dissection, cold perfusion, microvascular anastomosis, and autotransplantation salvaged this kidney and resolved the hypertension.     

Small kidney and hypertension: selection of patients for surgery

We studied 37 patients with various degrees of hypertension and a small unilateral kidney. Renal vein renin studies were shown to be positive on 19 occasions and negative on 18. Of those positive, 10 had severe and 1 moderate hypertension. Surgery cured 63.3%. In 27% blood pressure improved and 1 patient failed to respond. Eight patients had mild hypertension with a positive renal vein renin ratio (RVRR), but on observation their home blood pressures were normal without medication and they were not considered for surgery. Eighteen patients with mild hypertension and negative RVRR were also not operated. We believe that RVRR is important for a surgical decision, but only in severe and moderate hypertensives. In mild hypertension, measurement of blood pressure at home is normal on most occasions. These are hyperreactive patients and should not have surgery, regardless of the results of their RVRRs.     

Tailoring the Endovascular Management of Transplant Renal Artery Stenosis

In this study we analyze the different types of endovascular interventions (EVIs) in de novo transplant renal artery stenosis (TRAS) and its anatomical subtypes to examine any variation in recovery of allograft function, blood pressure control, EVI patency and allograft survival with respect to EVI type (DES: drug‐eluting stent, BMS: bare‐metal stent, PTA: percutaneous transluminal angioplasty). Forty‐five patients underwent a total of 50 primary EVIs (DES: 18, BMS: 26, PTA: 6). Patients were stratified according to medical co‐morbidities, graft characteristics, biopsy results, clinical presentation and TRAS anatomic subtypes (anastomotic: 26, postanastomotic: 17, bend‐kink: 2). There was significant improvement in allograft function and mean arterial blood pressure (MAP) control across all interventions (pre‐EVI‐creatinine [CR]: 2.8 ± 1.4, post‐EVI‐Cr: 2.1 ± 0.7, p < 0.001; pre‐EVI‐MAP: 117 ± 16, post‐EVI‐MAP: 112 ± 17, p = 0.03) with no significant difference among EVI types. There was no significant difference in allograft survival with respect to EVI type. Patency was significantly higher in EVIs performed with DES and BMS compared to PTA (p = 0.001). In the postanastomotic TRAS subtype, patency rates were significantly higher in DES compared to BMS (p = 0.012) in vessels of comparable reference diameter (≤5 mm).     

Renal artery stenosis in transplant patients

Although hypertension appears not infrequently among recipients of kidney transplants, renal artery stenosis is relatively rare as a causative factor. A 23-year experience of patients receiving kidney grafts at the Brigham and Women's Hospital was reviewed to ascertain the incidence of renal artery stenosis and its surgical management. Risk factors leading to the condition and selection of patients for operation are emphasized. The incidence of arterial stenosis severe enough to require operation was 2.7% of 914 kidney transplants; the overall incidence in these patients is unknown, although operated patients comprise about one-half of those undergoing arteriography to diagnose hypertension. The mean time for development of the condition was 21.4 months from date of engraftment. A successful outcome as measured by fall in blood pressure and/or serum creatinine was achieved in 14 of 21 patients (67%) in whom surgical repair of the effected artery was undertaken. Reparative surgery was unsuccessful in seven patients, although hypertension was improved in one of these individuals following transplant nephrectomy. Surgery was never undertaken in four patients because of chronic rejection noted on biopsy. There was no mortality. Operative repair should be offered to patients with renal artery stenosis leading to unmanageable hypertension or renal dysfunction, but withheld from those with documented chronic rejection regardless of major arterial compromise.