Silicone rubber trileaflet valve assessment using cardiovascular magnetic resonance imaging

Hydrodynamic valve performance is usually evaluated by effective orifice area (EOA), geometric orifice area (GOA) and transvalvular pressure gradients (PG). Magnetic resonance imaging (MRI) is a very efficient tool for assessing these parameters. In this study, we evaluated a silicone rubber trileaflet valve using MRI. EOA, GOA and PG were evaluated under steady (12 l/min - 20 l/min) and pulsatile (5 l/min) flow conditions using continuity equation, planimetry and simplified Bernoulli´s equation respectively; the contraction coefficient (Cc) and Reynolds number (Re) were also evaluated as hydrodynamic parameters. The highest EOAs were 0.75 cm² for steady flow conditions and 0.98 cm² for pulsatile flow. For pulsatile flow conditions greater GOA by planimetry was 1.43 cm². For both flow conditions the highest PGs were > 40 mmHg. Cc was on range from 0.8 to 0.86 under steady flow conditions and 0.68 for pulsatile flow at peak sytole. The Re was much greater than 2200 for all flow conditions. This study allowed the non invasive evaluation of a silicone rubber trileaflet valve under steady and pulsatile conditions with MRI in order to understand valve opening.