Retrospective Study of Patients Undergoing Percutaneous Intervention of the Transplant Renal Artery Stenosis

Renal transplantation is the standard treatment for patients with end-stage chronic kidney disease because it is effective in reducing the morbidity and mortality. Despite of the satisfactory results, some patients evolve with graft dysfunction and refractory hypertension due to transplanted renal artery stenosis (TRAS). TRAS is the main vascular complication of patients undergoing kidney transplantation, with a reported incidence ranging 1 to 23% in the different series in the literature, depending on the definition and diagnostic techniques used, manifesting most commonly between the 3rd month and the 2nd year after transplantation.

Percutaneous intervention of TRAS is widely accepted as a viable treatment option, but there are few long-term data on patients undergoing angioplasty. The aim of this study was to evaluate long term outcomes clinical in patients with TRAS underwent to percutaneous intervention with or without stent.

Renal transplantation is the standard treatment for patients with end-stage chronic kidney disease, as it is effective in reducing the morbidity and mortality of patients in this condition. Despite satisfactory results, some patients have graft dysfunction and difficult-to-control hypertension, with the main cause of transplanted renal artery stenosis (TRAS).

The incidence of TRAS varies from 1 to 23% in the various series in the literature, depending on the definition and diagnostic techniques used, most commonly occurring between the 3rd month and the 2nd year after transplantation. However, it may present at any time with refractory hypertension and / or graft dysfunction in the absence of rejection, ureteral obstruction or infection.

About 50% of TRAS cases occur at the anastomosis site and there seems to be no relationship with the type of anastomosis, whether end-to-end or end-to-side. TRAS is generally a consequence of clamp perfusion injury, incorrect suture technique, or fibrotic inflammatory reaction to suture material. Other factors attributed to TRAS are secondary to graft rejection, cytomegalovirus infection, and cadaveric donor graft. The last two factors are controversial in the literature. Late TRAS is related to progressive atherosclerosis.

The diagnosis of TRAS is made by clinical manifestations and / or by complementary exams. In addition to refractory hypertension, patients with TRAS may have increased serum creatinine, sudden graft deterioration and acute pulmonary edema. Color Doppler ultrasonography is the most commonly used method due to its easy access, low cost and does not require the use of contrast or radiolabels. However, its biggest limitation is the heavy reliance on operator expertise. It has a sensitivity of 87 to 94% and a specificity of 86 to 100%. TRAS is suspected when Doppler ultrasound has a peak systolic velocity (PSV) above 180 cm / s and a resistance index \<0.50.

Computed tomography provides three-dimensional images that may be superior to those of selective angiography, with the advantage of not requiring arterial puncture and requiring less contrast. Nuclear magnetic resonance is even superior to tomography, with a sensitivity of 67 to 100% and specificity of 75 to 100%. However, its availability is still limited, besides presenting high costs.

Renal arteriography is the gold standard for the diagnosis of TRAS. However, there is a need for high contrast volumes, which can precipitate acute renal failure, particularly in patients who already have renal dysfunction. Three-dimensional rotational angiography (3D-RA) appears as an auxiliary tool that can minimize the deleterious effects of contrast. The measurements obtained by 3D-RA showed a strong correlation with the measurements made by conventional angiography, demonstrating equivalent accuracy, without the need for additional projections, helping to perform the intervention.

Complications arising from transplanted kidney arteriography are puncture site hematomas, pseudoaneurysms, thromboembolism, arteriovenous fistulas, iliac artery dissection, graft artery dissection, occurring in less than 10% of cases. Due to the substantial risks and high costs, arteriography cannot be considered a screening method and is only indicated when a stenosis is suspected based on noninvasive exams.

Percutaneous intervention has been the method of choice for the treatment of TRAS with satisfactory results and few short-term complications, and its efficacy has been demonstrated, especially when using stents, in the various case series published in the literature. However, there is little data on long-term intervention, showing reduced mortality and graft preservation.

Evaluated data from the 2000-2005 United States Renal Data System (USRDS) and found no differences in mortality or renal loss in patients undergoing TRAS angioplasty (145 patients) compared to those who only underwent clinical treatment (678 patients) .

In a recently published systematic review, the authors demonstrated that percutaneous intervention with or without stenting was effective in the treatment of TRAS, with favorable results in terms of technical success (over 90%), clinical success, long graft patency, with few serious complications described. However, the authors report the absence of well-designed robust randomized studies, most of which are retrospective series of a single center with a low casuistic. The positive findings of this review contrast with the results found in the treatment of native renal artery stenosis, where stent revascularization showed no benefit in patients with atherosclerotic renovascular disease when compared to drug treatment. In this same article, the authors describe the inconsistency and lack of standardization in the methodology for defining the outcomes of the intervention on TRAS.

The Hospital do Rim e Hipertensão, an agency linked to the Federal University of São Paulo (Unifesp) in Brazil, is the world leader in renal transplantation, performing an average of 1000 transplants / year in recent years. From 2006 to January 2015, patients with suspected TRAS were referred for angiography in the Hemodynamics of Hospital São Paulo.

The aims of this study was to retrospectively evaluate all patients referred to service with suspected TRAS who underwent angiography and intervention.

Eligibility Criteria:
Inclusion Criteria:

* patients with clinical suspicion of transplanted renal artery stenosis.
* patients undergoing angiography of the transplanted renal artery.
* patients undergoing transplanted renal artery stenosis intervention with and without stent.

Exclusion Criteria:

* refuses to participate in the study.
* patients without clinical follow-up.
* patients who did not renal transplanted at the hospital do Rim.