Percutaneous transluminal dilation in renal transplant arterial stenosis

Management of transplant renal artery stenosis

Transplant renal artery stenosis is the most frequent vascular complication of transplantation. Early detection and correction reduce patients' morbidity and allograft dysfunction. Although noninvasive imaging can detect an underlying stenosis, angiography with subsequent angioplasty or stenting, or both, provides definitive diagnosis and treatment. With the introduction of alternative contrast agents and newer catheter and stent technology, these procedures can be performed safely with little risk of contrast-induced nephropathy or allograft loss.

Primary endoluminal stenting of transplant renal artery stenosis from cadaver and non-heart-beating donor kidneys

This study evaluated the efficacy of primary endovascular stenting in cases of transplant renal artery stenosis (TRAS) from cadaver and non-heart-beating donor kidneys. Patients with TRAS (n = 13) from a single-centre transplant population (n = 476) were treated by primary percutaneous angioplasty and endovascular stenting. The short-term efficacy of this intervention is demonstrated in terms of serum creatinine, glomerular filtration rate (GFR) biochemical, anti-hypertensive medications and mean arterial blood pressure control. Stenting for TRAS was performed in male (n = 10) and female (n = 3) recipients. The median age at transplantation was 55 yr (range 10-67 yr). Stenting occurred at a median duration of 410 d post-transplantation (range 84-5799 d). Mean serum creatinine (pre, 247 micromol/L; post, 214 micromol/L; p = 0.002), GFR (pre, 82.6 mL/min; post, 100.9 mL/min; p < 0.001), arterial blood pressure (pre, 104 mmHg; post, 97 mmHg; p = 0.036) and the number of anti-hypertensive medications required (pre, 3.4; post, 3.0; p = 0.002) showed significant improvement after post-endovascular therapy. There were no serious complications encountered. Primary endovascular stenting of TRAS produces a significant improvement in biochemical parameters of renal graft function and in blood pressure stability, with the benefit of low patient morbidity and single arterial puncture. Primary endoluminal stenting of TRAS is a safe and effective procedure for the treatment of TRAS.

Transplant renal artery stenosis: outcome after percutaneous intervention

PURPOSE

To assess the outcome of percutaneous transluminal angioplasty (PTA) and stent placement as the primary treatment for transplant renal artery stenosis (TRAS).

MATERIALS AND METHODS

A retrospective review of PTA and stent placement procedures performed for TRAS from April 1997 to July 2003 was conducted. Reviewed parameters included technical success, date of transplantation, dates of percutaneous intervention, mean arterial blood pressure, number of blood pressure medications, and serum creatinine level before and after intervention. Twenty-one interventions were performed in 18 allografts. The primary clinical indication for imaging and treatment was increased creatinine level in 12 allografts and hypertension in six allografts. Patency rates were estimated with use of the Kaplan-Meier method.

RESULTS

The technical success rate of PTA/stent placement was 100% and the clinical success rate was 94% (17 of 18 allografts). Thirteen interventions involved PTA alone, with eight combined PTA and stent insertions. The mean preintervention serum creatinine level among 12 allografts presenting with elevated creatinine levels was 2.8 mg/dL +/- 1.4 (SD), compared with a 1-month postintervention mean of 2.2 mg/dL +/- 0.7 (P = .03). Of six allografts that presented with hypertension, significant improvement was seen between the preintervention and 1-month postintervention mean systolic (174 mm Hg vs 135 mm Hg, P = .003) and diastolic (99 mm Hg vs 82 mm Hg, P = .02) pressures. These patients required a mean of 2.3 medications for blood pressure control before intervention, compared with a mean of 1.0 medications at 1 month after intervention (P = .002). Primary patency rates at 3, 6, and 12 months (+/-95% CI) were 94% +/- 6%, 72% +/- 12%, and 72% +/- 12%, respectively. Secondary patency rates at 3, 6, and 12 months (+/-95 CI) were 100%, 85% +/- 10%, and 85% +/- 10%, respectively. Mean follow-up time was 27 months. Of the eight allografts that underwent stent placement, all eight remained patent at last follow-up (mean, 18.3 months +/- 9.2). One major complication of a puncture site pseudoaneurysm occurred (5%).

CONCLUSION

Primary treatment of TRAS with PTA with or without stent placement has good intermediate-term patency and is associated with significant early improvement in blood pressure and creatinine level.

Percutaneous treatment of transplant renal artery stenosis in children

Percutaneous treatment of renal artery stenosis (RAS) is an accepted procedure and numerous reports have been published. However, experience with its use in RAS in the transplanted kidney in children is scarce. Since 1994 we have diagnosed RAS in seven children with the use of Doppler ultrasonography (US), confirming it with percutaneous angiography (PAG). In six of the seven patients percutaneous transluminal angioplasty (PTA) was performed. In one patient a metallic stent was placed due to the extension of the arterial lesion, and a second stent was placed in another child when a re-stenosis was diagnosed 1 month after the PTA. All patients presented with hypertension (de novo or 30% increase over previous values). After ruling out acute rejection, calcineurin inhibitor toxicity, and urinary obstruction, US was performed and, when an increase in arterial flux velocity was registered, PAG was also performed. Six children showed an increase in serum creatinine (Cr) and proteinuria. Blood pressure decreased after the procedure and Cr returned to previous levels in all children. One of the grafts was lost due to chronic transplant rejection 7 years later. The other children have a functioning kidney. Although this is a small group of patients, the consistently good results and the lack of reported experience prompted us to communicate our preliminary observation.

Angiographic evaluation and treatment of transplant renal artery stenosis

Transplant renal artery stenosis is an uncommon but important complication of renal transplantation. It is a potentially reversible cause of patient morbidity and allograft dysfunction, which can present both early and late in the post-transplant period. Although transplant renal artery stenosis can be detected using noninvasive imaging, definitive diagnosis and percutaneous treatment typically require the use of invasive angiographic techniques. In experienced hands, these studies can be performed safely, effectively and with a low risk of contrast induced nephrotoxicity when alternative contrast agents are used.

Gadolinium-based contrast and carbon dioxide angiography to evaluate renal transplants for vascular causes of renal insufficiency and accelerated hypertension

PURPOSE

To evaluate the utility and potential nephrotoxicity of gadolinium-based contrast angiography when used with carbon dioxide angiography in renal transplant patients with suspected vascular causes of renal insufficiency and/or accelerated hypertension.

MATERIALS AND METHODS

Thirteen consecutive renal transplant patients with suspected vascular causes of renal insufficiency and/or accelerated hypertension were evaluated with gadolinium-based contrast and CO2 angiography with use of digital subtraction techniques. Stenotic lesions were treated with angioplasty with/or without stent placement. No iodinated contrast agents were used. Serum creatinine levels were obtained before and at 24 and 48 hours after the procedure. An increase in creatinine levels greater than 0.5 mg/dL (44 micromol/L) was considered significant.

RESULTS

Nine patients were studied for renal insufficiency, two for accelerated hypertension, and two for both. All 13 studies were considered diagnostic. Significant stenoses were treated in four patients with angioplasty with or without stent placement. Two patients had progression of their renal insufficiency. One of these patients underwent biopsy and was found to have both acute and chronic rejection. The other patient underwent cardiac catheterization 2 days after a transplant renal artery angioplasty. In the remaining nine patients with renal insufficiency (creatinine range, 1.8-3.9 mg/dL [159-345 micromol/L]; mean, 2.7 mg/dL [239 micromol/L]), renal function improved or did not worsen.

CONCLUSION

Based on this limited study, gadolinium-based contrast angiography appears to be a promising supplement to CO2 angiography for the diagnosis and treatment of vascular lesions in patients with renal transplant insufficiency and/or accelerated hypertension. Further study is necessary to determine safety, optimal gadolinium dosage, and imaging parameters.

Post-transplant renal artery stenosis: impact of therapy on long-term kidney function and blood pressure control

PURPOSE

We assessed the long-term outcome of different treatment methods for transplant renal artery stenosis.

MATERIALS AND METHODS

Outcome data for 23 patients with transplant renal artery stenosis treated during a 16-year period were reviewed and analyzed.

RESULTS

There was a higher incidence of renal artery stenosis in cadaveric donor kidneys compared to living donor kidneys (2% versus 0.3%, p < 0.02), and in cadaveric kidneys from pediatric donors less than 5 years old compared to those from adults (13.2% versus 1.3%, p < 0.01). Six patients underwent primary medical treatment for renal artery stenosis, with a successful outcome in 4 (mean followup plus or minus standard error 57 +/- 22 months) and failure in 2. Of the patients 16 were treated with percutaneous transluminal angioplasty, including 12 who were cured or improved with respect to hypertension (followup 44.7 +/- 7.6 months). Five patients underwent surgical revascularization for renal artery stenosis with postoperative improvement of hypertension (followup 18.8 +/- 11.6 months). Overall, 21 of 23 patients (91%) were treated successfully for transplant renal artery stenosis with cure or improvement of associated hypertension. Posttreatment renal function was stable or improved in 18 patients, while renal function deteriorated due to parenchymal disease in 3.

CONCLUSIONS

Most patients with transplant renal artery stenosis can be treated successfully. Percutaneous transluminal angioplasty is the initial interventive treatment of choice for high grade renal artery stenosis. Surgical revascularization is indicated if percutaneous transluminal angioplasty cannot be done or is unsuccessful.

CO2 angiography--a technique for vascular imaging in renal allograft dysfunction

Use of iodinated contrast for vascular imaging can be associated with nephrotoxicity and hypersensitivity reactions. Renal injury following conventional angiography is more likely to manifest in the setting of preexisting renal dysfunction. In the setting of suboptimal renal allograft function, these considerations are particularly relevant. Recently, CO2 has received attention as a nontoxic, injectable, rapidly absorbed gas that is a cost-effective alternative to standard contrast agents in high-risk patients, such as renal transplant recipients. We report the clinical course of a patient with transplant renal artery stenosis and a serum creatinine of 2.8 mg/dl who has successfully undergone angiography and percutaneous transluminal angioplasty using CO2 as the sole contrast agent. This case illustrates the potential use for CO2 as a contrast agent for vascular imaging in patients with suboptimal renal function who require definitive vascular imaging or therapy.

Percutaneous transluminal angioplasty for transplant renal artery stenosis

A recent report has challenged the efficacy and safety of percutaneous transluminal angioplasty (PTA) for the treatment of transplant renal artery stenosis (TRAS). From January 1983 to December 1990, 24 PTA procedures were performed for TRAS in 18 patients. The stenoses were anastomotic in two cases, in the main renal artery in 14, and segmental in eight. After PTA, the residual stenosis was less than 20% in 14 (58%), 20%-50% in four (17%), and greater than 50% in six (25%). The mean diastolic blood pressure decreased from 106 mm Hg 1 day prior to PTA to 82 mm Hg 1 day after PTA. Long-term follow-up mean diastolic blood pressure (at 2-32 months) was 93 mm Hg (P less than .01). Eleven of the 18 patients (63%) had a 10% or greater reduction in diastolic blood pressure on long-term follow-up. Major complications occurred in two patients; one groin hematoma required surgical evacuation, and one polar infarct led to hypertension that was difficult to control. No surgical revisions of the transplant renal artery were necessary. The authors' data indicate that PTA should remain the treatment of choice for nonanastomotic TRAS.

Percutaneous transluminal renal angioplasty (PTRA) as a method of therapy for renovascular hypertension in children

The results of PTRA in treatment of renovascular hypertension in four children aged 5, 7, 13 and 15 are presented. All patients suffered from severe hypertension. Tests showed all of them to have fibromuscular dysplasia stenosis of the main renal artery and significant lateralization of renin levels. One suffered from associated polycystosis of kidneys and in another the renal artery stenosis was bilateral. In all patients successful patency was achieved. In one patient, the arterial pressure after PTRA was normalized, while in the others it was considerably improved. Two patients, tested 8 and 12 months after PTRA, were lost to further follow-up. In one of the remaining two, stenosis and hypertension reappeared 5 years after PTRA. After autotransplantation the patient was normotensive. In the other, also 5 years later, recurrent hypertension appeared related to the associated polycystosis.

Fibromuscular dysplasia in donor kidneys--experience with three cases

In 1987, three patients received kidney grafts bearing medial fibroplasia at our hospital. Two of the grafts were from a cadaveric donor and one was from a living related donor kidney. The vascular affection was known before transplantation. Only one of the recipients developed stenosis and hypertension. With balloon catheter dilatation, the progressive stenosis of the renal graft artery could, however, be successfully corrected.

Arteriography of renal transplantation

The arterial anatomy of renal transplants is often complex, with overlapping, tortuous vessels which prevent easy visualisation of the origins of the transplant artery. We have adopted a technique using smallbore catheters with non-selective 'flush' injections of contrast medium, high resolution magnification techniques and multiple oblique projections. A retrospective study over six years (1980 to 1985 inclusive) revealed 34 significant (greater than 50%) transplant artery stenoses (13 adults, 21 children) from 200 transplant arteriograms performed. During this period, 452 transplants were performed, 38% in children. The incidence of transplant artery stenosis was 7.5%. Percutaneous transluminal angioplasty was attempted in 11 patients (four adults, seven children), with technical success in only five (45.5%). The predominance of children in this group contributes to the poor success rate of percutaneous transluminal angioplasty in our hands, which we attribute to the small arteries involved, the acute vessel angulations seen and the tough undilatable stenoses which are encountered in transplants in paediatric patients. Fourteen patients with post biopsy arterio-venous fistulae are described and the role of embolisation in this condition is discussed. A simplified approach for the arteriography of live related donors is also described.

Percutaneous transluminal angioplasty of renal transplant artery stenosis

Renal transplant artery stenosis occurs in approximately 10% of renal transplants, and antihypertensive drugs, vascular reconstructive surgery, and percutaneous transluminal angioplasty may be used in its treatment. Details of 28 cases of renal transplant artery stenosis were collected from a postal survey of United Kingdom transplant centres. The success rate for angioplasty (63% clinical cure or improvement) is lower than in previous reports.

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.

[Transluminal dilatation and other nonsurgical catheter technics in the treatment of renovascular hypertension]

The development of percutaneous transluminal techniques has brought up new possibilities for causative treatment of renovascular hypertension. In renal artery stenosis transluminal angioplasty is meanwhile routinely applied; experience with angioplasty to date exceeds by far the number of 1000 published cases. Technical success is obtained in more than 90%. The clinical success in the therapy of reno-vascular hypertension is approximately 76% over all with nearly equal cure and improvement rates. In fibromuscular stenosis clinical success has been obtained in 95% with a cure rate of 56% and improval in 39%. The cure rate is particularly low in patients with atherosclerotic stenosis with 19%, however in 60% improvement has been obtained, resulting in clinical benefit in 79%. Results obtained by surgery seem to be superior to those of dilatation, especially with regard to cure rates. However, the differences are minor and are compensated by the evident advantages of transluminal dilatation, especially its easy application and lower risk. Thus, 8 years after its introduction in nephrology, transluminal dilatation is the therapy of choice in renal artery stenosis. Other nonoperative interventional techniques, including transcatheter aspiration and embolectomy, intraarterial thrombolysis, embolisation and modified angioplasty provided valuable alternatives to usual surgical therapy. However, experience with some of these procedures is still limited. The complication rate of transluminal angioplasty of 10-20%, necessitating surgery in nearly 5%, prohibits its uncritical use.

Anastomotic line renal artery stenosis after transplantation

We report on 5 patients with renal artery stenosis after renal transplantation. Renal arteriography showed the stenosis to be localized at the line of arterial anastomosis. The patients presented with refractory hypertension, with or without renal failure, 10 days to 13 months after transplantation. Percutaneous transluminal balloon angioplasty in 4 patients failed in 3 and produced temporary improvement in 1. Resection of the stenosis resulted in dramatic improvement of the clinical state in all 5 patients. Histological examination of the resected stenotic segment revealed a nodular fibrotic lesion at the anastomotic line in all cases, and was associated with extensive calcification in 3. Anastomotic line stenosis should be recognized as a specific entity causing transplant renal artery stenosis. The pathological changes observed explain the failure of transluminal angioplasty and suggest that surgical repair is the treatment of choice. Possible factors in the etiology of anastomotic line stenosis are discussed.

Percutaneous transluminal angioplasty in transplant renal artery stenosis: experience and review of the literature

Percutaneous transluminal angioplasty (PTA) was performed in five instances of renal transplant artery stenosis (RTAS) in four patients. Hypertension was present in all cases and improved after angioplasty together with reduction in medicine requirements. Abnormal renal function in four instances also improved after PTA. This reflects the current literature in which 76 of 90 patients were successfully treated by PTA (follow-up to 24 months), with two cases of recurrent stenosis, no mortality, and only a single case of graft loss. Vascular surgical repair succeeded in 130 to 180 patients, but graft loss occurred in 20 cases and recurrent stenosis in 11. Mortality was reported in five cases. Our review of the literature and experience suggests that PTA may be preferred in the treatment of RTAS.

Hypertension and kidney transplantation

Patients with kidney transplants are often hypertensive. Investigators have described the characteristics of this hypertension in man. Moreover, the hypertension of kidney transplant patients has a higher probability of being responsive to surgical intervention than does hypertension in the general population. Yet the mechanisms of the many varieties of posttransplantation hypertension are not known in detail. Detailed studies that would best be done in animal models are rare. Both medical and surgical management of this transplantation-associated complication needs further study.

Postbiopsy renal allograft arteriovenous fistula: therapeutic embolization

Two patients with large, postbiopsy renal allograft arteriovenous fistulae are presented. One patient also had a renal artery anastomotic stenosis. Prominent clinical features in these cases were deterioration of allograft function and severe hypertension. Following therapeutic embolization, combined with balloon angioplasty in the second patient, there was marked improvement in allograft function and a return to normal blood pressure.

Renal transplant artery stenosis and percutaneous transluminal angioplasty

Ten patients with renal transplant artery stenosis were treated with percutaneous transluminal angioplasty (PTA). All patients suffered from hypertension refractory to drug treatment. PTA was successful in five patients. Blood pressure improved significantly and the antihypertensive medication could be reduced or withdrawn. Acute angulation at the anastomosis prevented successful PTA in four patients. One inaccessible stenosis was corrected surgically. No significant complications arose. If a renal transplant artery stenosis is haemodynamically significant, PTA should be considered the method of first choice for correction.

The transplanted kidney. Diagnostic and interventional radiology

Following kidney allotransplantation a great number of complications threaten the patient and his graft, e.g. acute tubular necrosis, acute and chronic rejection, urologic and vascular complications and complications due to the immunosuppressive treatment. During the last decade a number of technical developments in radionuclide, ultrasonographic and radiographic imaging and intervention has significantly improved the possibility of early recognition and handling of such complications. Knowledge of the capability and limitations of the various techniques is of vital importance for their rational use. The aim of this review article is to give a short description of the various imaging modalities, the rational monitoring of the posttransplant patient, and possible handling of complications by the aid of imaging techniques.

Percutaneous transluminal angioplasty. The radiologist's contribution to the treatment of vascular disease

Percutaneous transluminal angioplasty is a nonsurgical treatment for vascular disease. It is relatively safe and economical and may be an alternative, or an adjunct, to surgery, or may be helpful where no surgical alternative exists. Percutaneous transluminal angioplasty is applicable to nearly every system, except the carotid bifurcation plaque.

Screening for transplant renal artery stenosis in hypertensive recipients using digital subtraction angiography

Digital subtraction angiography was used in 10 renal allograft recipients with sustained hypertension after transplantation to detect transplant renal artery stenosis. Recipients with end-to-end vascular anastomoses were visualized adequately in the anteroposterior projection. Two cases of transplant renal artery stenosis were identified by digital subtraction angiography and then verified by catheter angiography. Patients with end-to-side vascular anastomoses may require additional oblique projections. Digital subtraction angiography is a safe, noninvasive and cost-effective screening procedure to diagnose transplant renal artery stenosis in most recipients. Catheter angiography can be applied more selectively to those recipients with stenosis observed by digital subtraction angiography or when more detailed imaging is required.

Percutaneous transluminal renal angioplasty in renovascular hypertension due to atheroma or fibromuscular dysplasia

We attempted percutaneous transluminal renal angioplasty in 89 patients with hypertension and renal-artery stenosis (including 51 with atheromatous and 31 with fibromuscular stenoses) who were then followed for an average of 16 months (range, 4 to 40). Angioplasty was technically successful in 87 per cent of the fibromuscular stenoses and in 57 per cent of the unilateral atheromatous stenoses but in only 10 per cent of the bilateral atheromatous stenoses. After successful angioplasty, blood pressure was reduced to normal or improved in 93 per cent of the patients with fibromuscular dysplasia and in 84 per cent of the patients with atheromatous disease. Angiographic follow-up at an average of 21.8 months in 15 patients showed persistent relief of the stenoses and a 12 per cent average increase in kidney size. Renal angioplasty is effective for long-term control of hypertension in patients with renal-artery stenosis due to fibromuscular dysplasia or unilateral non-ostial atheroma.

Percutaneous transluminal dilatation of posttransplant renal artery stenosis: beneficial effects in two cases at high surgical risk

Two clinical cases are described in which percutaneous transluminal dilatation (PTD) determined the correction of hypertension and renal hypoperfusion due to renal artery stenosis of the transplanted kidney.

Balloon catheter dilatation of stenotic renal artery anastomoses. Experiments in the pig

Stenotic renal artery anastomoses were produced in pigs in order to investigate the effects of transluminal angioplasty. Six weeks after surgery unilateral dilatation with a modern balloon catheter was performed in 8 pigs. These animals were reexamined with angiography and pressure gradient recording 8 to 10 weeks after dilatation and with post-mortem angiography 8 to 10 weeks later. Only 2 arteries had minimal residual stenoses, while in 6 arteries the stenoses were completely eliminated. Microscopic examination showed thinning of the fibrotic vessel wall, with defects in the internal elastic lamina.