A new index measured by cardiovascular magnetic resonance imaging to detect mechanical heart valve malfunction

摘要

More than two thirds of valve replacement operations performed each year used mechanical heart valve. These valves are subject to complications such: pannus and/or thrombus formation. One other potential complication is a malfunction in one of the valve leaflets. It is then important to develop parameters that will allow a non-invasive diagnosis of such valve malfunction. In the present study, we evaluated under steady low flow (1–8 L/min) and pulsatile flow (3, 5 and 7 L/min) a bileafleat mechanical heart valve with normal function, 50% and 100% of one valve leaflet malfunction. Image analysis was performed using cardiovascular magnetic resonance imaging to evaluate transvalvular pressure gradients (TPG), effective orifice area and a new index given by central/lateral velocity ratio downstream of the valve. Our results showed that the flow upstream and downstream of the defective valve is highly influenced by malfunction severity. TPG did not allow differentiating valve malfunction at low flow under steady and pulsatile conditions. However the new index given by central/lateral ratio allowed differentiating the presence of valve malfunction using a single transverse velocity measurement.