Feasibility of intracardiac echocardiography for assessment of renal blood flow in humans

Abstract

Abstract Background Intracardiac echocardiography (ICE) is routinely used for guiding cardiac ablation procedures. However, the potential of ICE for measurement of renal artery (RA) blood flow (RABF) has not been fully exploited. Aims To investigate the feasibility of ICE for the assessment of RABF and to evaluate its reproducibility in humans. Methods The study included 15 patients undergoing catheter ablation of atrial fibrillation guided by ICE (age: 61±14 years, body mass index: 30±5 kg/m2, left ventricular ejection fraction: 57±6%, serum creatinine: 80±29 μmol/l). During sinus rhythm, the ICE probe was withdrawn from the right atrium to the inferior vena cava until the right RA with its ostium became visible. Blood flow in the RA was visualized by colour flow mapping. The RA diameter was measured at 10 mm from the ostium. RABF at this location was measured by pulse wave Doppler. Velocity-time integral (VTI) was delineated manually and averaged over five consecutive beats. RABF was calculated by the formula: RABF = (RA radius)2 x π x VTI x heart rate. To assess reproducibility of the method, the ICE probe was repositioned in the right atrium and the measurement of RABF was repeated by the same operator. Results The right RA was visualized in all 15 patients. No procedure-related clinical complications occurred. The mean RA radius was 2.5±0.4 mm. In all cases, the angle of incidence during the measurement of VTI was <5°. The mean RABF was 403±163 and 399±156 ml/min during the first and the second measurement, respectively (p=0.7 by a paired t-test, coefficient of variation 5,3±3,8%; see Figure for Bland-Altman plot). Conclusions This study demonstrated that measurement of RABF by ICE is feasible and has reasonable intra-observer reproducibility. The method can be used to study RABF during various interventions and hemodynamic conditions. Figure 1. Intra-individual reproducibility Funding Acknowledgement Type of funding source: None