Donors with renal artery stenosis: fit to donate

Kidney donation from hypertensive donors is now an accepted norm in live related kidney transplantation. The use of hypertensive donors with renal artery stenosis due to atherosclerosis and fibromuscular dysplasia is still debated. The prime concern is about the deleterious effect of hypertension on the donor and the risk of recurrence of such lesions in the solitary kidney. Even as the response of atherosclerotic renal artery stenosis to revascularisation is unpredictable, there is an improvement in blood pressure following revascularisation of kidneys with fibro-muscular dysplasia. The first use of such kidney donors was reported in 1984 and, since then, there have been a few reports of successful use of kidneys from donors with renal artery stenosis. We report here two interesting cases of successful transplantation of kidneys from live related kidney donors with hypertension due to renal artery stenosis who became normotensive with good graft function in the recipient. We conclude that moderately hypertensive donors with renal artery stenosis are fit to donate.     

Imaging modalities for renal artery stenosis in suspected renovascular hypertension: prospective intraindividual comparison of color Doppler US, CT angiography, GD-enhanced MR angiography, and digital substraction angiography

The aim of the study was to evaluate the diagnostic accuracy of Color Doppler US, CT Angiography (CTA), and GD-enhanced MR Angiography (MRA) compared with digital subtraction angiography (DSA) for the detection of renal artery stenosis in patients with clinically suspected renovascular hypertension. Fifty-eight patients with suspected renovascular hypertension were enrolled in the study. All patients underwent Color Doppler US, CTA and GD-enhanced MRA. DSA was the gold standard method for the number of renal arteries, existence and degree of stenosis, or evidence of fibromuscular dysplasia. DSA depicted 132 renal arteries, 16 stenoses, and 4 arteries with fibromuscular dysplasia. Color Doppler US failed to detect 1 main and 14 polar arteries. CTA depicted all main renal arteries and 7/16 polar arteries, but failed to detect stenosis in two accessory vessels. Likewise, MRA did not detect stenotic accessory renal arteries, depicted 9/16 polar renal arteries, but missed two main renal arteries. All methods depicted the four main renal arteries with fibromuscular dysplasia. The overall sensitivity, specificity, and positive and negative predictive accuracy were 75%, 89.6%, 60% and 94.6%, respectively, for color Doppler US; 94%, 93%, 71%, and 99%, respectively, for CTA; and 90%, 94.1%, 75%, and 98%, respectively, for GD-enhanced MRA. CTA and GD-enhanced MRA have comparable and satisfactory results with respect to the negative predictive accuracy of the suspected renal artery stenosis. The concept of an imaging algorithm including US as screening test when appropriate and CTA or MRA as the second step-procedure is suggested. Therefore, DSA may be reserved for cases with major discrepancies or therapeutic interventions.     

Imaging Modalities for Renal Artery Stenosis in Suspected Renovascular Hypertension: Prospective Intraindividual Comparison of Color Doppler US,CT Angiography,GD-Enhanced MR Angiography,and Digital Substraction Angiography

The aim of the study was to evaluate the diagnostic accuracy of Color Doppler US, CT Angiography (CTA), and GD-enhanced MR Angiography (MRA) compared with digital subtraction angiography (DSA) for the detection of renal artery stenosis in patients with clinically suspected renovascular hypertension. Fifty-eight patients with suspected renovascular hypertension were enrolled in the study. All patients underwent Color Doppler US, CTA and GD-enhanced MRA. DSA was the gold standard method for the number of renal arteries, existence and degree of stenosis, or evidence of fibromuscular dysplasia. DSA depicted 132 renal arteries, 16 stenoses, and 4 arteries with fibromuscular dysplasia. Color Doppler US failed to detect 1 main and 14 polar arteries. CTA depicted all main renal arteries and 7/16 polar arteries, but failed to detect stenosis in two accessory vessels. Likewise, MRA did not detect stenotic accessory renal arteries, depicted 9/16 polar renal arteries, but missed two main renal arteries. All methods depicted the four main renal arteries with fibromuscular dysplasia. The overall sensitivity, specificity, and positive and negative predictive accuracy were 75%, 89.6%, 60% and 94.6%, respectively, for color Doppler US; 94%, 93%, 71%, and 99%, respectively, for CTA; and 90%, 94.1%, 75%, and 98%, respectively, for GD-enhanced MRA. CTA and GD-enhanced MRA have comparable and satisfactory results with respect to the negative predictive accuracy of the suspected renal artery stenosis. The concept of an imaging algorithm including US as screening test when appropriate and CTA or MRA as the second step-procedure is suggested. Therefore, DSA may be reserved for cases with major discrepancies or therapeutic interventions.     

Incidence of donor renal fibromuscular dysplasia: does it justify routine angiography?

BACKGROUND: The use of digital subtraction angiography (DSA) versus helical CT angiography (CTA) or MR angiography (MRA) for live renal donor evaluation is still controversial. Although CTA and MRA can detect some proximal moderate to severe arterial changes caused by fibromuscular dysplasia (FMD), mild and distal moderate FMD are not detected well without angiography. METHODS: This is a retrospective chart review of all potential, normotensive live renal donors at our center from July 1995 to June 2001. One hundred fifty-nine patients completed the donor evaluation process and underwent DSA. RESULTS: Seven cases of FMD, an incidence of 4.4%, were discovered. These patients were eliminated from donation. The distribution of renal vessels for our 159 patients was single arteries bilaterally, 64.8%; single left with multiple right, 16.4%; double left with single right, 9.4%; and multiple bilateral arteries, 9.4%. Three of the seven FMD patients had bilateral disease. Two of the seven (28.6%) FMD patients have subsequently required antihypertensive medications, with one requiring angioplasty of a progressive FMD stenotic lesion. CONCLUSIONS: We are concerned that CTA or MRA may overlook mild cases of DSA-detectable FMD. All seven FMD patients had single left renal arteries and would have undergone left donor nephrectomy. This would have resulted in their remaining right native kidneys having mild to moderate FMD in six of seven patients and in four donor kidneys having mild to moderate FMD. The need for antihypertensive medications in two of these seven potential donors within 4 years of their evaluation supports previous literature reports.     

Renal arteriovenous fistula associated with fibromuscular dysplasia

A case is reported of a woman with long-standing progressive hypertension and an abdominal bruit who on angiography demonstrated fibromuscular dysplasia of the right renal artery and an arteriovenous fistula in the upper pole of the right kidney. The various causes of renal arteriovenous fistula are reviewed. The relationship of mural aneurysms seen in fibromuscular dysplasia and the formation of arteriovenous fistulas by rupture of these aneurysms is discussed. Review of the English literature indicates a probable causal relationship between fibromuscular dysplasia of the renal arteries and intrarenal arteriovenous fistulas.     

The use of spiral computed tomographic angiography for the assessment of living kidney donors

BACKGROUND: Recent reports suggest that spiral computed tomographic (CT) angiography can replace conventional angiography and intravenous urography for the assessment of potential kidney donors. The purpose of this study is to assess the accuracy of spiral CT in potential kidney donor workup. METHODS: Over a period of 1 year, from December 1995 to December 1996, 16 consecutive potential renal donors had intravenous pyelography, percutaneous transfemoral angiography with selective renal angiography and spiral CT angiography. The spiral CT and renal angiograms were assessed independently by two radiologists. The number of renal arteries, presence or absence of renal artery stenoses and associated parenchymal abnormalities were assessed. RESULTS: A total of 39 renal arteries were detected. Conventional transverse scans viewed in a cine loop format detected all 39 vessels, while the maximum intensity projection and shaded surface display demonstrated only 37. All 39 vessels were detected by the catheter angiography. With the exception of one potential donor with fibromuscular dysplasia, 15 donors were accepted. There was 100% accuracy between the two methods of visualization for the renal arteries. A simple renal cyst was noted in both spiral CT and conventional angiogram, while another had gallstones in spiral CT. CONCLUSIONS: Spiral CT angiography performed as an outpatient procedure is less invasive, less expensive, and provides good images of the arterial and venous anatomy. It has the potential to replace conventional catheter angiography and intravenous pyelogram in the assessment of potential renal donors.     

Percutaneous transluminal angioplasty for renovascular hypertension in children

Percutaneous transluminal angioplasty (PTA) has been developed over the past 8 years as an alternative to reconstructive surgery for renovascular hypertension. We report three cases and review the use of PTA in children with renal artery stenosis. At least 37 cases of PTA have been reported in patients whose ages ranged from 1.3 to 17 years (mean 10 years). Of these, 10 had fibromuscular dysplasia; 13 unspecified unilateral renal artery stenosis; 4 bilateral stenosis; 4 neurofibromatosis; 4 renal transplant; 1 atherosclerosis; and 1 postsurgical stenosis. Nine of 10 patients with fibromuscular dysplasia were cured and 3 of 4 with renal transplant arterial stenosis were cured or improved. There were 11 failures of PTA, including all 4 patients with neurofibromatosis and 1 with transplant arterial stenosis. We conclude that PTA is the treatment of choice for children with hypertension due to fibromuscular dysplasia and should be attempted for stenosis of the transplanted renal artery. Other lesions resulting in renal artery stenosis may not be as amenable to dilation and should be considered on an individual basis.R. L. Chevalier is an Established Investigator of the American Heart Association     

Treatment of renal artery fibromuscular dysplasia with balloon angioplasty: a prospective follow-up study.

OBJECTIVES: to assess restenosis rates and blood pressure response after percutaneous transluminal renal angioplasty (PTRA) in patients treated for fibromuscular dysplastic renal artery stenosis. METHODS: a prospective 12-month follow-up study of 27 patients with 31 treated renal artery stenosis. Follow-up assessment included colour-coded duplex sonography (CCD) of renal arteries, monitoring of blood pressure, antihypertensive medication, and creatinine measurements before discharge and at 3, 6, and 12 months. Primary end point was defined as a haemodynamically significant restenosis >60% assessed by CCD. RESULTS: there was a cumulative 23% restenosis rate at 12 months. Arterial hypertension was cured or improved in 93% of patients immediately after the intervention and remained cured/improved in 74% of patients at 12 months of follow-up. Renal failure present in five patients before PTRA stabilised or improved in all patients. CONCLUSION: although restenosis rate after PTRA in fibromuscular dysplasia is as high as in non-ostial atherosclerotic lesions, there remains a considerable higher therapeutic effect. Profound pressure response and recurrent arterial hypertension with restenosis support the high probability of a renovascular origin of arterial hypertension in this young and otherwise healthy population compared to patients with atherosclerotic renal artery lesions.     

Preoperative evaluation of living renal donors with gadolinium-enhanced magnetic resonance angiography

BACKGROUND: Preoperative evaluation of living renal donors includes an intra-arterial digital subtraction angiography (DSA). Inasmuch as this technique is invasive, uses radiation and an iodine-containing contrast medium, an alternative technique would be preferable. The purpose of this study was to determine the accuracy of gadolinium-enhanced magnetic resonance (MR) angiography in the visualization of renovascular anatomy for the preoperative evaluation of renal donors. METHODS: Twenty-four consecutive potential renal donors underwent gadolinium-enhanced MR angiography before the standard of reference, intra-arterial DSA. Both modalities were evaluated in a blinded manner. The results were correlated with the surgical findings. RESULTS: Three MR angiograms were technically unacceptable because of inadequate breath-hold. The remaining 21 donors had 47 renal arteries, including 5 accessory renal arteries, which were all visualized by MR angiography. MR angiography failed to visualize one case of subtle fibromuscular dysplasia in the distal part of a renal artery. In one donor, a small accessory renal artery, which had not been visualized on DSA, was encountered during nephrectomy. CONCLUSION: Gadolinium-enhanced MR angiography is an accurate minimally invasive method for the detection of accessory renal arteries in the preoperative evaluation of potential renal donors. The accuracy for excluding stenosis in general is high; however, the depiction of stenosis that are located far distally, or in the branch vessels, is less accurate. Advantages of gadolinium-enhanced MR angiography over the currently used method, intra-arterial DSA, are the minimal invasive nature, lower costs, and superiority in detecting venous anomalies, renal cysts, and tumors.     

Fibromuscular dysplasia of the renal arteries: a radiological review

Fibromuscular dysplasia is the most common cause of renovascular hypertension in young patients. Digital subtraction angiography is still the best investigation used to determine the location, extent and complication of renal artery involvement. String of beads appearance (reflecting multiple stenoses), aneurysms, focal or tubular stenosis are classic angiographic appearances. The aim of this pictorial essay is to illustrate the various imaging findings of renal artery fibromuscular dysplasia.     

Misleading Diagnosis of Renal Artery Stenosis by Magnetic Resonance Angiography in a Patient with Primary Aldosteronism

A 24-year-old woman presented with severe hypertension. A diagnostic evaluation for secondary hypertension was undertaken. A duplex ultrasonography followed by a magnetic angiography suspected fibromuscular dysplasia. Unexpectedly, a contrast-enhanced angiography performed for renal angioplasty showed normal renal arteries. Primary aldosteronism was then evoked on the basis of decreased plasma renin and increased plasma aldosterone and aldosterone/renin ratio. After a CT-scan disclosed a left adrenal tumour, the patient underwent a left laparoscopic adrenalectomy. Pathological findings confirmed a benign adrenocortical adenoma. Blood pressure and aldosterone levels were normalized after surgery. Thus, clinicians should be aware of false-positive results of magnetic resonance angiography that could hide other causes of secondary hypertension.     

A preliminary study of the role of duplex scanning in defining the adequacy of treatment of patients with renal artery fibromuscular dysplasia.

Renal artery fibromuscular dysplasia is a well-known cause of hypertension whose presence is confirmed by its typical arteriographic appearance. The functional significance of these lesions is often difficult to determine, particularly when both renal arteries are involved. Duplex scanning has been shown to be accurate for the detection of renal artery stenosis and estimation of the degree of narrowing. To test whether duplex scanning results after intervention correlate with clinical outcome, we reviewed the studies on nine patients with renal artery fibromuscular dysplasia who had been treated by either angioplasty or surgery. A total of 18 arteries were treated. Fourteen of the 18 treatments were successful as measured by a reduction in blood pressure and antihypertensive drugs. In four instances treatment was unsuccessful. For those patients who had clinical improvement, the hemodynamic parameters from the renal artery also improved. In the patients for whom treatment failed, the velocities recorded from the site of narrowing did not improve after intervention. Thus it appears that duplex scanning along with the clinical results may be used to document the basis for failing to improve after treatment be it angioplasty or operation.     

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.     

Fibromuscular dysplasia: noninvasive evaluation of unusual case of renal and mesenteric involvement

Fibromuscular dysplasia is the most common cause of renovascular hypertension in young patients. It primarily involves the renal and carotid arteries, and it is less common in the coronary, iliac, and visceral arteries. Digital subtraction angiography is still the best investigation to determine the location, extent, and complications of renal artery involvement. However, currently, other imaging modalities such as ultrasonography, computed tomography, and magnetic resonance imaging can reveal these findings noninvasively. We present the case of a 43-year-old woman who presented with high blood pressure and headache. Imaging revealed fibromuscular dysplasia of the renal arteries and the superior mesentery artery.     

Epidemiology and clinical presentation

Renovascular disease appears to be increasing in prevalence, particularly in older subjects with atherosclerotic disease elsewhere. Its clinical manifestations and presentation are changing because of rapid advances in medical therapy and other comorbid events. Although fibromuscular dysplasia and other diseases affecting the renal artery can produce the syndrome of renovascular hypertension, atherosclerotic renal artery stenosis is the most common clinical entity. It can produce a spectrum of manifestations, ranging from asymptomatic ("incidental"), identified during angiographic evaluation of other conditions, to progressive hypertension to accelerated cardiovascular disease with pulmonary edema and advanced renal failure. With the widespread application of drugs which block the renin-angiotensin system, including angiotensin-converting enzyme inhibitors and angiotensin antagonists, many cases of renovascular hypertension remain unsuspected and never produce adverse effects. Clinicians need to be alert to the potential for disease progression, with the potential for total renal artery occlusion and/or loss of viable renal tissue. Selection of patients for renal revascularization depends on individual balance of risks and benefits regarding the likely outcomes regarding both improvements in blood pressure control and preservation of renal function.     

An unusual case of fibromuscular dysplasia

The case of a patient with abdominal angina due to fibromuscular dysplasia is described. Arteriography revealed dysplasia of both renal arteries and occlusion at their origins of both coeliac and mesenteric arteries. Digital subtraction angiography later showed fibromuscular dysplasia of both carotid artery systems. An unusually long right internal iliac artery allowed it to be anastomosed to the superior mesenteric artery. Follow-up studies have confirmed patency of this reconstruction.     

Extrinsic compression of the renal artery by diaphragmatic crus

Extrinsic compression of the renal artery due to a fibromuscular band originating from the diaphragm was encountered in a 26-year-old patient who had systemic hypertension associated with stenosis and kinking of one of her renal arteries. After surgical decompression, the renal artery assumed a normal expansion with disappearance of hypertension. Six other cases of extrinsic compression of the renal artery have been found in the literature. Surgical treatment is mandatory in all cases because the mechanism that causes the lesion makes percutaneous transluminal angioplasty illusory.     

USE OF SPIRAL COMPUTERIZED TOMOGRAPHY IN LIEU OF ANGIOGRAPHY FOR PREOPERATIVE ASSESSMENT OF LIVING RENAL DONORS

PURPOSE: We evaluate whether spiral computerized tomography (CT) can be used in lieu of renal angiography for preoperative assessment of living renal donors, with special attention to multiplicity of renal vasculature. MATERIALS AND METHODS: A total of 47 living renal donor candidates were evaluated with spiral CT and all but 2 underwent donor nephrectomy. Patients were divided into early and late groups because there was a learning curve with spiral CT. In the early group 18 donors underwent renal angiography as well as spiral CT and 10 underwent nephrectomy after spiral CT only. In the late group 5 had dual radiographic evaluation for ambiguities in spiral CT interpretation and 12 underwent nephrectomy after spiral CT only. Spiral CT was performed and interpreted blind to angiographic results, and vice versa. RESULTS: Spiral CT identified 50 of 52 renal arteries (96%) found at surgery overall and 23 of 25 (92%) found at surgery after spiral CT only. Two accessory arteries were missed in the 10 early group donors evaluated with spiral CT only, yielding an early negative predictive value of 80%. Renal angiography identified another accessory artery missed by spiral CT in the early group. All 3 missed vessels were identified retrospectively. No arteries found at surgery were missed in the late group (negative predictive value 100%), although there were 2 false-positive results detected by spiral CT relative to renal angiography in 1 candidate renal unit. Overall accuracy to predict early renal artery division relative to surgical findings was 93% for spiral CT and 91% for renal angiography. However, early renal artery division was clinically significant for only 1 of 11 vessels found at surgery. Spiral CT demonstrated 4 anomalous venous returns and renal angiography identified none. However, spiral CT missed 2 accessory veins and identified only 1 of 2 fibromuscular dysplasia cases. Total cost for spiral CT and renal angiography was $886 and $2,905, respectively. CONCLUSIONS: Spiral CT is a reasonably good alternative to renal angiography for living renal donor assessment but there is a profound learning curve for performance and interpretation. Renal angiography is still the gold standard with respect to the identification of arterial multiplicity and fibromuscular dysplasia, and it should be used adjunctively in cases with spiral CT ambiguity. Neither spiral CT nor renal angiography is ideal for the assessment of early renal artery division which is seldom an issue. The benefits of spiral CT over renal angiography are potentially lower morbidity, improved donor convenience and reduced cost.     

Successful treatment of renovascular hypertension due to fibromuscular dysplasia by intravascular ultrasound-guided atherectomy

A 22-year-old man presented with renovascular hypertension, based on a stenosis of the distal portion of the right renal artery with a "string of beads"-like appearance. An intravascular ultrasound image at the renal artery lesion revealed irregularity of the vascular wall. Directional atherectomy was performed and histopathology of atherectomised tissues showed medial fibroplasia, a common type of fibromuscular dysplasia. After atherectomy his hypertension was markedly improved. We report here a case of renovascular hypertension due to fibromuscular dysplasia, successfully diagnosed and treated with IVUS-guided renal atherectomy.     

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.