Vascular Complications After Kidney Transplantation: A Prospective National Multicenter Study - The DAN-PTRAIII Study
* To determine the incidence of arterial inflow problems and venous outflow problems as causes of impaired renal function and/or treatment-resistant hypertension after kidney transplantation, when all kidney-transplant recipients in Denmark are evaluated according to uniform, well-defined clinical criteria. * To investigate the efficacy and safety of catheter-based balloon treatment (percutaneous transluminal angioplasty, PTA) for these vascular complications, of which transplant renal artery stenosis is by far the most common. * To assess whether novel imaging and functional diagnostic methods can predict treatment response.
• 1\. At least one of the following clinical criteria (1 or 2) must be fulfilled:
• Graft dysfunction, defined by at least one of the following:
‣ Acute reduction in estimated glomerular filtration rate (eGFR) \>15% on two consecutive measurements at least 2 weeks apart, with other causes excluded (rejection, obstruction, infection).
⁃ eGFR \<50% of the expected value 30 days after kidney transplantation of unknown cause.
⁃ Decline in eGFR \>30% after initiation of an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker.
• Persistent resistant hypertension for more than 6 weeks after kidney transplantation, defined as:
‣ 24-hour ambulatory systolic blood pressure \>130 mmHg despite treatment with at least three classes of antihypertensive medication at maximally tolerated doses (including diuretics, if tolerated).
• Together with at least one of the following radiological criteria:
• CT or MR angiography demonstrating a lumen reduction ≥50%.
• Doppler ultrasound showing:
∙ Peak systolic velocity in the renal artery ≥200 cm/s and a renal renal ratio (velocity at stenosis / velocity in distal artery) \>4.
‣ Acceleration time \>70 ms in intrarenal arteries.
• 2\. In cases of strong clinical suspicion of a vascular complication where CT or MR angiography cannot reliably exclude graft artery or vein stenosis, patients may be referred for confirmatory invasive investigations.
• Before PTA, catheter-based angiography and translesional pressure measurements are performed to confirm whether the patient meets the radiological eligibility criterion for PTA:
• Stenosis ≥70%.
• Stenosis 50-69% if at least one of the following criteria is met:
‣ Mean translesional pressure gradient ≥10 mmHg.
⁃ Systolic pressure gradient ≥20 mmHg.
⁃ Renal Pd/Pa ≤0.8.
⁃ If pressure measurements cannot be obtained, treatment is based on the operator's clinical judgement.