Hemodynamic Changes in the Right Ventricle Induced by Variations of Cardiac Output: A Possible Mechanism for Arrhythmia Occurrence in the Outflow Tract

Figure 1. Streamlines color coded with velocity magnitude along the RV at peak systolic phase (left) and mid diastolic phase (right) obtained using in vivo PC-MRI in a healthy athletic male proband at resting conditions. Red color corresponds to high velocity and the blue color represents slow velocity regions. The PC-MRI data of the healthy male volunteer is used for qualitative representation of the blood flow and as a reference for validating the in vitro flow patterns of the silicone model (see Methods section). Recirculation regions at ventricular filling are marked with arrows.

Figure 2. Time evolution of MKE averaged over the RVOT and RV (top left), temporal variation of TKE averaged over the RVOT and RV (top right), comparison of the time evolution of kinetic energies at the RVOT (bottom left) and time evolution of WSS averaged over the RVOT and RV (bottom right) obtained using in vivo PC-MRI in a healthy athletic male proband at resting conditions. Red squares correspond to the RVOT, blue circles represents the entire RV and green triangles correspond to the RVOT TKE.

Figure 3. MKE and peak MKE averaged over the RVOT for varying cardiac output levels (top left). Laminar viscous dissipation and peak laminar viscous dissipation averaged over the RVOT for varying cardiac output levels (top right). Maximum viscous shear stress and peak maximum shear stress averaged over the RVOT for varying cardiac output levels (bottom left). WSS and peak WSS averaged over the RVOT for varying cardiac output levels (bottom right). All quantities are obtained using 3D-PTV in vitro. Red circles correspond to peak values, whereas blue squares represent time averaged values.

Figure 4. Spatial distribution of WSS at peak systole for varying cardiac output levels obtained using 3D-PTV in vitro (Case I: 4.05 L/min, Case II:4.44 L/min, Case III:4.65 L/min, Case IV:5.32 L/min,). Red color corresponds to high WSS, whereas blue color represents low WSS. A substantial increase in WSS in the RVOT, particularly in the anterior RVOT (free wall, black arrow) is observed with increasing cardiac output.

Figure 5. Time evolution of WSS averaged over the RVOT for healthy, early ARVC/D and moderate ARVC/D cases (left) obtained using in vivo PC-MRI. Spatial distribution of WSS at peak systole for the healthy case (middle) and moderate ARVC/D case (right).

Figure 6. Schematic workflow for the assessment of the velocity information in the novel right heart model. A high resolution magnetic resonance imaging (MRI) heart scan of a healthy male proband has been performed. A silicone model cast was 3D printed out using the geometry obtained via MRI. The right heart model was manufactured by brushing the surface of wax positive (Elastrat GmbH, Switzerland). 3D-PTV measurements have been performed in the anatomically accurate right heart model. Streamlines color coded with velocity magnitude were obtained along the superior vena cava (SVC), inferior vena cava (IVC), right atrium (RA), RV and RVOT.

Figure 7. Comparative analysis of the in vivo and in vitro flow fields. Streamlines color coded with velocity magnitudes at the peak systolic phase in vitro (top left) and in vivo (bottom left) (higher velocity magnitudes occur in the proximity of the RVOT, whereas the velocity magnitudes are comparatively lower at the RV subtricuspid region and the apex). Dashed lines represent the investigation domain where the statistical analysis has been performed. The linear regression analysis between velocity magnitude normalized by peak velocity magnitude in vivo and in vitro (top right) and Bland-Altman analysis between velocity magnitude normalized by peak velocity magnitude in vivo and in vitro (bottom right). Filled blue circles represent a different time-point in the cardiac cycle.

Figure 8. Time evolution of the in vivo longitudinal strain normalized by peak systolic strain at RV free wall and in vitro strain normalized by peak systolic strain at the RV free wall (red color represents in vivo strain and the blue color represents in vitro strain).