Duplex of Kidney Transplant Graft: Criteria for Transplant Renal Artery Stenosis (TRAS)
Localization and Surgical Anatomy
According to the source, the best diagnostic sign of TRAS is focal elevation of peak systolic velocity (PSV) with post-stenotic turbulence. The most common location is the arterial anastomosis, followed by the proximal segment of the artery; the lesion can occur at any part of the transplant artery or be diffuse. Stenosis of the iliac artery proximal to the renal graft mimics TRAS (pseudo-TRAS).
The most common anastomosis variant is the end of the graft artery to the side of the external iliac artery (living donor and cadaveric). In cadaveric transplants, a variant with a donor aortic patch carrying one or more renal arteries anastomosed to the external iliac artery is possible. Less commonly, the end of the graft artery is connected to the end of the internal iliac artery or its branches.
Direct Criterion of Stenosis by Velocity Ratio
According to the source, in significant stenosis (>50%), the PSV at the aliasing (stenosis) zone is at least 3 times (3:1) higher than the PSV in the feeding artery measured 2 cm proximally. This is a universal principle for diagnosing stenosis applicable in different vascular zones.
Normal Velocity Parameters of the Renal Artery
For reference, normal values of the native renal artery from the guide by B.V. Blagodir are provided.
| Segment | PSV, cm/s |
|---|---|
| Renal artery (normal) | 90–120 |
| Distal segments | 70–90 |
| Sinus | 30–50 |
| Parenchyma | 10–20 |
EDV normally does not exceed 1/3 of PSV, and this PSV/EDV ratio is maintained up to the cortex. The normal intra-organ spectrum is fast, with a slightly rounded systolic peak and anterograde diastole (low-resistance organ flow with constant perfusion); at the peak, a split may occur — early systolic peak (ESP).
PSV and AT Thresholds Specifically for TRAS
In the presented fragments, specific validated numerical thresholds for PSV and acceleration time (AT/AcT) for diagnosing transplant renal artery stenosis and grading its severity are not provided [to clarify]. Diagnosis in the source relies on qualitative signs (focal PSV elevation, post-stenotic turbulence) and the universal 3:1 velocity ratio.
Frequently asked questions
What is the direct criterion for transplant artery stenosis?
Focal elevation of PSV with post-stenotic turbulence; for stenosis >50%, PSV at the stenosis site is at least 3 times (3:1) higher than PSV in the feeding artery 2 cm proximally.
Where is TRAS most commonly located?
Most commonly at the site of the arterial anastomosis, then in the proximal segment of the artery; diffuse lesions can occur at any part of the graft artery.
What is pseudo-TRAS?
Stenosis of the iliac artery proximal to the renal graft origin, mimicking transplant artery stenosis.
What are the normal velocities in the renal artery for reference?
Renal artery PSV 90–120 cm/s, distal segments 70–90 cm/s, sinus 30–50 cm/s, parenchyma 10–20 cm/s; EDV not more than 1/3 of PSV.
Are there specific PSV and AT thresholds for TRAS in the fragments?
No, specific numerical thresholds for PSV and AT specifically for transplant artery stenosis are not provided in the sources [to clarify]; qualitative assessment and the 3:1 ratio are used.