Radermacher et al used Doppler ultrasonography to evaluate patients with renal arterial stenosis. They used the resistance index (RI) to identify patients unlikely to benefit from revascularization procedures. The authors are from Medizinische Hochschule Hannover.



(1) end-diastolic velocity in cm/sec

(2) maximal systolic velocity in cm/sec


resistance index =

= (1 - ((end-diastolic velocity) / (maximal systolic velocity))) * 100



• A resistance index >= 80 was associated with worsening renal function after a revascularization procedure.

• A resistance index < 80 was associated with a good chance of improved renal function and improvement in blood pressure following a revascularization procedure.


Additional factors associated with a poor outcome after a revascularization procedured:

(1) not smoking

(2) advanced renal disease (creatinine clearance < 40 mL per minute)

(3) male gender


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