Abstract 3013: Clinical Utility of Doppler Ultrasound Imaging for Screening of In-Stent Restenosis of Renal Arteries
Background: Non-invasive screening for renal artery in-stent restenosis (ISR) is frequently performed using doppler ultrasound (D-US). Due to the the lack of defined doppler-velocity criteria for stented renal arteries most centers rely on doppler-velocity parameters established for non-stented vessels, in order to screen patients for ISR. Since stents change the biomechanical properties of arteries, our hypothesis was that flow velocities will be increased in the absence of flow-limiting lesions.
Purpose: To assess the clinical value of D-US for screening of renal artery ISR and to identify the most accurate velocity parameter that identifies or excludes significant ISR lesions.
Methods: We included consecutive patients (N=50) with history of renal artery stenting, who underwent renal angiography following abnormal D-US. Significant ISR was defined as >50% luminal narrowing as measured by quantitative angiography (Heartlab Cardiac Solutions). Doppler velocity information, including peak-systolic velocity (PSV), end-diastolic velocity (EDV) and reno-aortic ratio (RAR) was correlated with quantitative angiography measurements. Linear regression and Pearson correlation was performed using the SAS statistical package.
Results: Patients with abnormal D-US (>60% by established parameters for non-stented vessels) underwent renal angiography to rule out ISR. Fifty stented renal arteries, with 17 to 81% angiographic stenosis, were included. There was a linear and statistically significant positive correlation (p<0.001) between PSV and RAR by D-US and percent stenosis by quantitative angiography. PSV ≥300cm/sec was the most sensitive, specific and accurate parameter to identify significant ISR.
Conclusion: The utility and reliability of doppler ultrasound to screen for renal artery ISR is demonstrated. A peak systolic velocity of ≥300cm/sec has the best sensitivity, specificity, PPV, NPV and accuracy to detect significant ISR (>50%).