Renal Artery Stenosis Diagnosis Criteria

Jul 25, 2024

Renal Artery Stenosis and Diagnosis Criteria

Key Concepts:

Importance of Color Doppler and Spectral Doppler

  • Velocity criteria: Use 180 cm/s as a benchmark.
  • If turbulence is found in the main renal arterial segment, place a spectral Doppler on that area.

Renal to Aortic Ratio (RAR)

  • Why RAR is needed?
    • Unlike peripheral or carotid arteries, renal artery stenosis often occurs at the origin, especially in elderly patients.
    • No proximal renal artery segment is usually available for comparing flow velocity.
  • Procedure: Compare PSV
    • Compare the Proximal Segment Velocity (PSV) of the aorta to the PSV at the stenotic segment of the renal artery.

Interpretation in Elderly Patients

  • Low Cardiac Output Consideration
    • Elderly patients may have heart disease leading to lower overall cardiac output.
    • Example: Aortic PSV could be 35-40 cm/s.
    • Renal artery PSV at the stenosis area may be 140 cm/s.
  • Ratio Standards
    • Even if renal artery PSV doesn't meet the 180 cm/s criteria, a ratio >3.5 between renal artery PSV and aortic PSV still indicates stenosis.

Summary

  • Summary: Use a combination of absolute velocity and relative velocity (RAR) for accurate diagnosis of renal artery stenosis.