Criteria

Severity[6]

  • Moderate stenosis: 50% to 70% reduction in vessel diameter

  • Severe stenosis: >70% reduction in vessel diameter

  • Total occlusion: 100% reduction in vessel diameter.

Invasive measurements

  • Catheter-measured hyperaemic peak-to-peak gradient of ≥20 mmHg or a mean gradient of ≥7-10mmHg[32][33]

  • Trans-stenotic ratio of <0.9 measured by pressure wire.[34]

Duplex ultrasound criteria[27]

  • Ultrasound diagnostic criteria for significant renal artery stenosis are:

    • Renal artery to aorta peak systolic velocity ratio >3.5 (>50% stenosis)

    • Peak systolic velocity >200 cm/sec with evidence of post-stenotic turbulence (>50% stenosis)

    • Peak systolic velocity >200 cm/sec and end-diastolic velocity >150 cm/sec (>80% renal artery stenosis)

  • Renal resistive index >0.8 was used as a criterion historically, but as resistive index is now known to be influenced by extrarenal factors such as systemic haemodynamics, it is no longer routinely used in the diagnosis of RAS.[28][29]

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