OP.7A.07] FEASIBILITY AND REPRODUCIBILITY OF INTRARENAL MEASUREMENTS OF PRESSURE AND FLOW

Abstract

Objective: Efficacy of catheter-based percutaneous transluminal renal angioplasty with stent placement (PTRAS) has been called into question. Selection of renal arteries suitable for intervention is currently based on anatomical grading of the stenosis by angiography. In the coronary circulation, functional measurements are successfully used in conjunction with angiography to discriminate between solitary coronary lesions and diffuse microvascular disease. It is conceivable that functional measurements may better predict therapeutic efficacy of PTRAS, but the feasibility and reproducibility of these pressure and flow measurements have not yet been assessed.Design and method: Prospective clinical study to assess the feasibility and reproducibility of intrarenal pressure and flow measurements at rest and during maximal hyperemia in stable patients aged 18–75 and eGFR > 45 ml/min/1.73m2 with an indication for renal or coronary angiography. Proximal (i.e., aortic) and distal (i.e., intrarenal) pressures and distal flow velocities were measured both under baseline and hyperemia. To test for reproducibility of the measurements, pharmacologically induced hyperemia was induced twice within the same patient, using intrarenal dopamine 30 μgram/kg. Results: We conducted intrarenal pressure and flow measurements in 25 patients (see Figure 1 for example). After searching for the optimal dosage and technical settings, 16 measurements were successful. Baseline characteristics are depicted in table 1. Mean renal flow reserve (RFR) was 2.33 (range, 1.08–4.23) in measurement 1 and 2.13 (range, 0.84–3.83) in measurement 2 (intraclass correlation coefficient (ICC) 0.87 (CI, 0.68–0.96). Mean renal fractional flow reserve (rFFR) was 0.96 (range, 0.57–1.00) vs. 0.96 (range, 0.50–1.00) with ICC 0.98 (0.94–0.99). Mean flow velocity increase was 36.1 cm/s (range, 2.3–88.7) vs. 34.0 cm/s (range, −4.4–86.2). Bland-Altman plots for APVmax and RFR show an acceptable discrepancy between the measurements and limits of agreement with consistent variability at increasing means. Conclusions: Performance of simultaneous pressure and flow measurements appears feasible and reproducible in patients with an indication for renal or coronary angiography.