Abstract 4143148: Feasibility of Volumetric Echo-PIV for Assessing Right Ventricular Blood Flow in Pulmonary Hypertension

Background: Pulmonary hypertension (PH) is a progressive condition leading to right ventricular (RV) dilatation and failure. It is hypothesized that RV remodeling can be predicted by changes in the complex three-dimensional (3D) RV blood flow. Early identification of these changes could help prevent establishing overt PH. This study tests the feasibility of volumetric Echo-PIV (V-Echo-PIV) technique that considers conservation of mass principle and RV wall dynamics to assess 3D RV blood flow field using standard clinical echocardiography equipment. Hypothesis: To assess whether V-Echo-PIV can differentiate between normal and pulmonary hypertension states without requiring high-fidelity replication of actual blood flows. Goals: Distinguishing RV blood flow in PH with or without RV dysfunction compared to the normal state. Methods: Followed by Optison™ injection, contrast echocardiography using a Philips EPIQ CV9 system and 3D matrix probe (x5-1) was performed to capture B-mode images of the RV. The V-Echo-PIV method estimated 3D RV blood flow velocities, refined by iterative correction to comply with RV geometry and mass conservation. Global flow properties such as kinetic energy and vortex impulse were calculated to distinguish between normal and pathological conditions. Results: The study compared healthy RV with the RVs from patients with pulmonary hypertension, with a normal-sized RV and with a dilated and dysfunctional RV. Evaluation of the iterative flow estimation process showed rapid convergence, confirming the robustness of the refinement approach. Blood flow visualization revealed distinct patterns during diastolic filling and systolic ejection (Fig. 1). Quantitative analysis showed reduced intensity of cycle-averaged kinetic energy, the energy dissipation, and enstrophy along with diastolic average of vortex impulse in patients compared to the control subject, indicating altered blood flow dynamics in PH (Figs. 2 and 3). Conclusions: Results show PH patients have altered flow properties even without overt RV dysfunction based on the qualitative visualization and the global metrics of blood flow. Further studies are needed to validate clinical value and ensure statistical significance. Nevertheless, this study demonstrates the potential of V-Echo-PIV, enhanced by the principles of mass conservation and RV geometry dynamics, to distinguish between normal and diseased conditions without necessitating high-fidelity replication of actual blood flows.