#4504 Quantitative Changes in Intracardiac Flow Parameters During Hemodialytic Sessions

Abstract

Background and Aims Hemodialysis sessions exert an acute impact on cardiac geometry and mechanics. The recent development of quantitative measurement of intracardiac fluid-dynamics and analysis of vortexes offers a new opportunity to better understand the fine changes in intracardiac hemodynamic associated with hemodialysis sessions. Vortexes rise in cardiac chambers from blood flow and they are defined as circular fluid structures with rotational movement around a central virtual axis, capable of storing kinetic energy during rotation. They must be distinguished from turbulences, in which various vortexes of different sizes coexist chaotically, resulting in a rapid dissipation of kinetic energy. Our aim was to assess the impact of a hemodialytic session on new parameters originated from intracardiac flow dynamics. Method We included 26 consecutive patients on chronic hemodialysis in clinically stable phase. They underwent echocardiography including intracardiac fluid-dynamic analysis by Color Vector Flow Mapping (Hyperdoppler) before and after a single dialysis session(Fig. 1-A). Patients with hemodynamically relevant valvular disease were excluded. A complete fluid-dynamics evaluation included the measurement of multiple parameters such as vortex area (VA); vortex length (VL); vortex depth (VD). Bland Altman Plot has been used to assess intra and inter-observer variability. Changes in fluid dynamics after dialysis sessions were tested using the Wilcoxon matched-pairs test. Results The Mean Vortex Area (VA) (p = 0.034) (Fig. 1-B), Vortex Depth (VD) (p = 0.024) (Fig. 1-C) and Vortex Length (L) (p = 0.037) (Fig. 1-D) were significantly reduced after the dialysis session. A similar trend towards the reduction of Direct Flow (DF) parameter after the session was found, which was significantly larger for patients with larger baseline left ventricular (V) end-diastolic diameter (r = 0.446; p = 0.037) (Fig. 1-E). On the other hand, mean Vortex Intensity (VI) was significantly increased after dialysis (p = 0.046) (Fig. 1-F). Among energy parameters, the intradialytic change in Kinetic Energy Fluctuation (KEF) (r = 0.4; p = 0.058) and Shear Stress Fluctuation (SSF) (r = 0.435; p = 0.038) (Fig. 1-G) were most closely correlated with intradialytic weight change. Fluid dynamic parameters had similar trends of intradialytic change, with stronger correlations among geometric parameters. Delta changes in VA were closely related to changes in VI (p<0.001) or LV (p<0.001). VI was also correlated with VL (p<0.001) and with Kinetic Energy Dissipation (KED) (p = 0.030), which was also correlated with VL (p = 0.044). KEF was correlated with KED (p = 0.001) and SSF ( = 0.022). Finally, changes in SSF were correlated with those in Flow Force Parameter (p = 0.033) and Flow Force Angle (p = 0.034), that were very closely correlated each other (p<0.001). Conclusion This is the first study assessing the impact of haemodialytic sessions on intracardiac flow dynamics. Measurement of hyperdoppler indices on haemodialysis chair was feasible and reliable in the whole population. Our results uncovered quantitative changes of echocardiographic parameters of vortex geometry and energy during haemodialysis.