Angioplasty vs stent in the treatment of transplant renal artery stenosis

Interventional Management of Vascular Complications after Renal Transplantation

BACKGROUND

 Kidney transplantations are increasing due to demographic changes and are the treatment of choice for end-stage renal disease. Non-vascular and vascular complications may occur in the early phase after transplantation and at later stages. Overall postoperative complications after renal transplantations occur in approximately 12 % to 25 % of renal transplant patients. In these cases, minimally invasive therapeutic interventions are essential to ensure long-term graft function. This review article focuses on the most critical vascular complications after renal transplantation and highlights current recommendations for interventional treatment.

METHOD

 A literature search was performed in PubMed using the search terms "kidney transplantation", "complications", and "interventional treatment". Furthermore, the 2022 annual report of the German Foundation for Organ Donation and the EAU guidelines for kidney transplantation (European Association of Urology) were considered.

RESULTS AND CONCLUSION

 Image-guided interventional techniques are favorable compared with surgical revision and should be used primarily for the treatment of vascular complications. The most common vascular complications after renal transplantation are arterial stenoses (3 %-12.5 %), followed by arterial and venous thromboses (0.1 %-8.2 %) and dissection (0.1 %). Less frequently, arteriovenous fistulas or pseudoaneurysms occur. In these cases, minimally invasive interventions show a low complication rate and good technical and clinical results. Diagnosis, treatment, and follow-up should be performed in an interdisciplinary approach at highly specialized centers to ensure the preservation of graft function. Surgical revision should be considered only after exhausting minimally invasive therapeutic strategies.

KEY POINTS

  · Vascular complications after renal transplantation occur in 3 % to 15 % of patients.. · Image-guided interventional procedures should be performed primarily to treat vascular complications of renal transplantation.. · Minimally invasive interventions have a low complication rate with good technical and clinical outcomes..

CITATION FORMAT

· Verloh N, Doppler M, Hagar MT et al. Interventional Management of Vascular Complications after Renal Transplantation. Fortschr Röntgenstr 2023; DOI: 10.1055/a-2007-9649.

Risk factors of transplant renal artery stenosis in kidney transplant recipients

BACKGROUND

Transplant Renal Artery Stenosis (TRAS) is a recognized vascular complication after kidney transplantation. The overall risk predictors of TRAS are poorly understood.

METHODS

Retrospective analysis of patients with suspected TRAS (Doppler ultrasound PSV > 200 cm/s) who underwent angiographic study in a single center between 2007 and 2014. All patients with stenosis > 50% were considered with TRAS. Stenosis restricted in the body of the artery was also analyzed in a subgroup.

RESULTS

274 patients were submitted to a renal angiography and 166 confirmed TRAS. TRAS group featured an older population (46.3 ± 11.0 vs. 40.9 ±14.2 years; p = 0.001), more frequent hypertensive nephropathy (30.1% vs. 15.7%; p = 0.01), higher incidence of Delayed Graft Function (DGF) (52.0% vs. 25.6%; p < 0.001) and longer Cold Ischemia Time (CIT) (21.5 ± 10.6 vs. 15.7 ± 12.9h; p < 0.001). In multivariable analyses, DGF (OR = 3.31; 95% CI 1.78‒6.30; p < 0.0001) was independent risk factors for TRAS. DM and CIT showed a tendency towards TRAS. The compound discriminatory capacity of the multivariable model (AUC = 0.775; 95% CI 0.718‒0.831) is significantly higher than systolic blood pressure and creatinine alone (AUC = 0.62; 95% CI 0.558-0.661). In body artery stenosis subgroup, DGF (OR = 1.86; 95% CI 1.04‒3.36; p = 0.03) and Diabetes Mellitus (DM) (OR = 2.44; 95% CI 1.31‒4.60; p = 0.005) were independent risk factors for TRAS.

CONCLUSION

In our transplant population, DGF increased more than 3-fold the risk of TRAS. In the subgroup analysis, both DGF and DM increases the risk of body artery stenosis. The addition of other factors to hypertension and renal dysfunction may increase diagnostic accuracy. TRAS TRIAL REGISTRED: clinicaltrials.gov (n° NCT04225338).

Endovascular Treatment of Transplant Renal Artery Stenosis: A Systematic Review and Meta-analysis

OBJECTIVE

Endovascular treatment through either percutaneous transluminal angioplasty (PTA) alone or stenting has been previously used as a treatment for transplant renal artery stenosis (TRAS). This review aimed to investigate the results of endovascular treatment for renal artery stenosis in transplanted kidneys as compared with the outcomes of interventions, medical management, and graft survival in non-TRAS patients.

METHODS

A systematic review of PubMed, Google Scholar, Cochrane, and Scopus was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in which studies that reported outcomes of the treatment of TRAS via the endoluminal approach were identified, and their results were meta-analyzed.

RESULTS

Fifty-four studies with a total of 1522 patients were included. A significant reduction of serum creatinine level was found, favoring the stenting group, with a mean difference of 0.68 mg/dL (95% confidence interval (CI), 0.17-1.19; Z=2.60, p=0.0009). Comparison of pre- and post-intervention values of any intervention revealed a significant decrease in overall serum creatinine level (0.65 mg/dL; 95% CI, 0.40-0.90; Z=5.09, p=0.00001), overall blood pressure, with a mean difference of 11.12 mmHg (95% CI, 7.29-14.95; Z=5.59, p=0.00001), mean difference in the use of medications (0.77; 95% CI, 0.29-1.24; p=0.002), and peak systolic velocity (190.05; 95% CI, 128.41-251.69; p<0.00001). The comparison of serum creatinine level between endovascular interventions and best medical therapy favored endovascular intervention, with a mean difference of 0.23 mg/dL (95% CI, 0.14-0.32; Z=5.07, p<0.00001). Graft survival was similar between the treated patients and those without TRAS (hazard ratio, 0.98; 95% CI, 0.75-1.28; p=0.091). The overall pooled success rate was 89%, and the overall complication rate was 10.4%, with the most prevalent complication being arterial dissection.

CONCLUSION

The endovascular treatment of TRAS improves graft preservation and renal function and hemodynamic parameters. PTA + stenting appears to be a more effective option to PTA alone in the stabilization of renal function, with additional benefits from decreased restenosis rates. Further high-quality studies could expand on these findings.

Update on Treatment of Hypertension After Renal Transplantation

PURPOSE OF REVIEW

To incorporate novel findings on pathophysiology and treatment of posttransplant hypertension.

RECENT FINDINGS

(1) The sodium retaining effects of CNIs are mediated by stimulation of the thiazide-sensitive sodium chloride co-transporter in the distal convoluted tubule and in this regard chlorthalidone was proven to be an effective antihypertensive drug in renal transplantation. (2) Local and not systemic activation of the renin-angiotensin-aldosterone system plays a crucial role in the pathogenesis of posttransplant hypertension. (3) Recent randomized controlled trials failed to prove the presumed superiority of renin-angiotensin blockers in kidney transplantation. (4) Steroid-free and mammalian target of rapamycin-based immunosuppressive drug combinations did not show favorable effects on blood pressure control. (5) In a recent report the risk of non-melanoma skin cancer was higher with thiazide diuretics. But the increased cancer risk in transplant recipients is mainly attributed to comorbidities, such as diabetes and hypertension and of course to the transplantation condition itself or the obligatory application of immunosuppression, and has little to do with the antihypertensive medication Actual recommendations about BP targets in adult renal transplant recipients are coming from a post hoc analysis of a large randomized trial with another primary endpoint. Unless convincing studies on treatment of hypertension after renal transplantation are available, the ESC/ESH Guidelines 2018 should apply for these patients.

Hypertension in Kidney Transplant Recipients: Where Are We Today?

PURPOSE OF REVIEW

Cardiovascular disease is the leading cause of death and allograft loss among kidney transplant recipients, and hypertension is an independent risk factor for cardiovascular morbidity of this patient population. The etiology of hypertension is multifactorial, including pre-transplant volume overload, post-transplant recipient and donor-associated variables, and transplant-specific causes (immunosuppressive medications, allograft dysfunction and surgical complications such as transplant artery stenosis).

RECENT FINDINGS

No randomized controlled trials have assessed the optimal blood pressure targets and explored the best antihypertensive regimen for kidney transplant recipients. According to the large observational studies, it is reasonable to achieve a blood pressure goal of equal to or less than 130/80 mmHg in the long-term follow-up for minimizing the cardiovascular morbidity. The selection of antihypertensive agents should be based on the patient's co-morbidities; however, the initial choice could be calcium channel blockers especially in the first few months of transplantation. In patients with cardiovascular indications of renin-angiotensin-aldosterone system inhibition, given the well-described benefits in diabetic and proteinuric patients, it is reasonable to consider the use of renin-angiotensin-aldosterone system inhibitors. There is a need for future prospective trials in the transplant population to define optimal blood pressure goals and therapies.

Diagnosis and Treatment of Early Transplant Renal Artery Stenosis: Experience From a Center in Eastern China

Few studies have focused on the clinical characteristics of transplant renal artery stenosis (TRAS) with early onset. Sixteen cases diagnosed with TRAS in our center from January 2014 to August 2018 were retrospectively analyzed. Sixteen transplant patients without TRAS were selected as controls. The median diagnostic time for TRAS was 47.5 days after transplantation. No significant difference was observed between the TRAS group and the control group. The serum creatinine level (Scr), estimated glomerular filtration rate, systolic/diastolic blood pressure, graft artery peak systolic velocity (PSV), and resistive index of intersegmental artery (RI-ISA) between the 2 groups were (5.55 ± 3.49) and (1.89 ± 0.85) mg/dL; (17.83 ± 14.94) and (49.39 ± 19.96) mL/min; (143.50 ± 9.49)/(86.14 ± 7.38) and (130.38 ± 18.86)/(82.81 ± 12.52) mm Hg; (3.39 ± 1.57) and (1.31 ± 0.51) m/s; and (0.51 ± 0.10) and (0.67 ± 0.13), respectively. All showed statistical significance except the diastolic blood pressure. The Scr, estimated glomerular filtration rate, systolic/diastolic blood pressure, graft artery PSV, and RI-ISA in the TRAS group prior and after treatment were (5.55 ± 3.49) and (3.20 ± 1.50) mg/dL; (17.83 ± 14.94) and (25.60 ± 13.29) mL/min; (143.50 ± 9.49)/(86.14 ± 7.38) and (128.07 ± 16.16)/(75.71 ± 7.56) mm Hg; (3.39 ± 1.57) and (2.00 ± 1.04) m/s; and (0.51 ± 0.10) and (0.61 ± 0.10); all showed statistical significance. Receiver operating characteristic analysis showed an area under curve of 0.8616 for PSV and 0.8535 for RI-ISA in diagnosing TRAS. Patients with TRAS in our center showed a unique characteristic of early onset. The most prominent clinical symptom of TRAS is increasing Scr level instead of refractory hypertension. Screening of color Doppler flow imaging with a graft artery PSV >2.5 m/s and RI-ISA <0.5 could yield a preliminary diagnosis of TRAS. Percutaneous transluminal angioplasty/stenting could effectively improve allograft function as well as color Doppler flow imaging indexes.

Endovascular Treatment of Transplant Renal Artery Stenosis: Evaluation of Postoperative Outcomes and Risk Factors for Recurrence

Angioplasty with or without stenting has become a well-established procedure to treat transplant renal artery stenosis (TRAS). We evaluated our experience on postoperative outcomes following the intervention and identified potential predictive factors of TRAS recurrence. Consecutive patients who underwent endovascular treatment of TRAS were retrospectively reviewed. The study end points were the technical success, 30-day postoperative complications, and the estimated glomerular filtration rate (eGFR). Thirty-two patients underwent endovascular treatment for TRAS. The technical success rate was 96.6%. Complications were observed for 7 (21.9%) patients: 4 had a dissection, 2 a pseudoaneurysm, and 1 (3.1%) patient developed an acute pulmonary edema. The mean eGFR significantly increased at 7 days, 3 months, and 6 months postintervention (43.1, 44.9, and 44.3 vs 33.9 mL/min/1.73 m2 preoperatively, P < .05). The TRAS recurrence was observed in 7 (21.9%) patients. These patients had significantly higher preoperative peak systolic velocity and systolic rise time (5 vs 4 m/s, P = .0383 and 103 vs 80 milliseconds, P = .0148, respectively). Endovascular treatment of TRAS is associated with high technical success and significant improvement in renal function. Further studies are required to confirm predictive factors of TRAS recurrence following endovascular treatment.