Treating blood vessel problems after a kidney transplant

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This is a nationwide observational program in Denmark that applies uniform clinical and radiological criteria to identify arterial inflow and venous outflow problems after kidney transplantation. Patients who meet predefined clinical signs (graft dysfunction or persistent resistant hypertension) and radiologic criteria undergo catheter angiography with pressure measurements and intravascular ultrasound, and may receive percutaneous transluminal angioplasty (PTA). The project tracks short-term safety, procedural complications, and clinical outcomes including kidney function and blood‑pressure control. It also tests whether novel imaging and functional diagnostics predict which patients will respond to balloon treatment.

Why it matters

Who can join: the full rules

Inclusion Criteria:

1\. At least one of the following clinical criteria (1 or 2) must be fulfilled:

1. 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.
2. 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:

1. CT or MR angiography demonstrating a lumen reduction ≥50%.
2. Doppler ultrasound showing:

   1. Peak systolic velocity in the renal artery ≥200 cm/s and a renal-renal ratio (velocity at stenosis / velocity in distal artery) \>4.
   2. 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:

1. Stenosis ≥70%.
2. 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.

Exclusion Criteria:

1. Inability to provide informed consent.
2. Concurrent biopsy demonstrating rejection requiring treatment.
3. Pregnancy.
4. Previous PTA of the same vessel.
5. Patients unable to tolerate any form of antithrombotic therapy and therefore not eligible for stent placement.

Where it's running

• Aarhus University Hospital
  Aarhus, Denmark Recruiting
• Rigshospitalet
  Copenhagen, Denmark Recruiting
• Odense University Hospital
  Odense, Denmark Recruiting

Study contacts

• Principal investigator: Mark Reinhard, MD, PhD — Aarhus University Hospital
• Study coordinator: Mark Reinhard, MD, PhD
• Email: markrein@rm.dk
• Phone: +45 40460321

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.