Experimental Investigation of Left Ventricular Flow Patterns After Percutaneous Edge-to-Edge Mitral Valve Repair.

Mitral valve percutaneous edge-to-edge repair (PEtER) is a viable solution in high-risk patients with severe symptomatic mitral regurgitation. However, the generated double-orifice configuration poses challenges for the evaluation of the hemodynamic performance of the mitral valve and may alter flow patterns in the left ventricle (LV) during diastole. This in vitro study aims to evaluate the hemodynamic modifications following a simulated PEtER. A custom-made mitral valve was developed, and two configurations were tested: (i) a single-orifice valve with mitral regurgitation and (ii) a double-orifice mitral valve configuration following PEtER. The hemodynamic performance of the valve was evaluated using Doppler echocardiography and catheterization, while the flow patterns in the LV were investigated using particle image velocimetry (PIV). The tests were run at a stroke volume of 65 mL and a heart rate of 70 bpm. PEtER was found to significantly reduce the regurgitant volume (15 vs. 34 mL). There was a good agreement between Doppler and catheter transmitral pressure gradients (peak gradient: 9 vs. 7 mm Hg; mean gradient: 4 vs. 3 mm Hg) as well as an excellent agreement between maximal velocity measured by Doppler and PIV (1.60 vs. 1.58 m/s). Vortex development in the LV during diastole was significantly different after repair. PEtER significantly increased the amplitude of Reynolds and viscous shear stresses, as well as the number of high shear regions in the LV, potentially promoting thromboembolism events.