Mock loop testing of On-x prosthetic mitral valve with Doppler echocardiography

Previous in vitro testing (mainly in aortic position) and clinical experience (often based on Doppler echocardiographic observations) demonstrated an excellent hemodynamic behavior of the On-X valve. However, integrative studies including simultaneous hemodynamic pressure and flow measurements and Doppler echocardiography are lacking. Using our computer-controlled mock loop system, two samples of the Mitral 27/29 and one sample of the Conform-X Mitral 25/33 are tested in mitral position. Data include transvalvular pressure gradient and flow as well as transthoracic Doppler echocardiography. The valves are tested under three pressure conditions (ventricular systolic pressure of 100, 130, and 160 mm Hg) at three different heart rates (60, 100, and 140 beats/min). In addition, ventricular pressure conditions simulating fibrillation are imposed. Both valve types show similar hydrodynamic characteristics and have an effective orifice area of 2.1 cm2 and a performance index of 0.56 for a cardiac output of 3.5 L/min. Regurgitant volumes remain below 6 ml.