Vascular Complications After Kidney Transplantation

Kidney transplantation is performed 250-300 times annually in Denmark and substantially improves survival, quality of life, and reduces the burden of comorbidities in patients with end-stage kidney disease. Despite these benefits, vascular complications, particularly transplant renal artery stenosis (TRAS), remain a major cause of morbidity. Reported incidence of TRAS varies widely (1-23%), reflecting retrospective study designs and inconsistent diagnostic criteria. TRAS are classified into three main types: anastomotic (TRAS-A), post-anastomotic (TRAS-P), and long-segment bend/kink (TRAS-B), with most cases diagnosed within the first two years post-transplant. Severe stenoses can critically impair graft perfusion, leading to reduced renal function and treatment-resistant hypertension. Percutaneous transluminal angioplasty (PTA) for TRAS is a well-established procedure performed according to the same principles as coronary balloon angioplasty; however, the role of stent placement remains uncertain. PTA without stenting is associated with higher restenosis rates compared to PTA with stenting, yet evidence regarding graft function, survival, and blood-pressure control remains conflicting. Adverse events related to PTA occur in approximately 10% of patients and are generally mild. Serious adverse events are observed in fewer than 5% of patients and include procedure-related internal bleeding and vascular access-site complications. Severe internal bleeding may require blood transfusion and endovascular vessel occlusion and can, in rare cases, result in loss of the transplanted kidney. Access-site vascular complications may present as bleeding, thrombosis, or pseudoaneurysm. Against this background, the nationwide prospective multicentre DAN-PTRAIII study aims to establish the true incidence of arterial inflow and venous outflow problems in Danish kidney-transplant recipients, evaluate the efficacy and safety of balloon angioplasty, and explore novel imaging and functional diagnostic methods for predicting treatment response.