Abstract 3551: Correction of Acute Functional Mitral Regurgitation: Development of a New Epicardial Device
Objectives: Left ventricular remodeling with tethering of the papillary-chordal apparatus is the most important factor leading to functional mitral regurgitation (FMR). We assessed the hypothesis that an epicardial device designed to reposition the papillary muscles will reduce FMR without affecting diastolic function.
Methods: Acute FMR was induced by aortic banding in 7 sheep. Aortic, left ventricular and atrial pressures, left ventricular volumes, aortic blood flow, mitral annulus diameter and ECG were recorded. Left ventricular end diastolic and end systolic volume, stroke volume, the constant of passive left ventricular stiffness, and Tau were measured or calculated from pressure volume loops. Mitral regurgitant flow was calculated as the difference between aortic stroke volume and total left ventricular stroke volume.
Results: Application of an epicardial device reduced acute FMR from 14.4±5.4 to 7.7±5.2 mL (p<0.001) without decreasing mitral annulus diameter in diastole (p=0.075) or systole (p=0.080). Left ventricular end diastolic volume decreased from 241.5±52.5 to 227.6±46.5 mL (p=0.044) after application of the epicardial device. Passive left ventricular stiffness increased from 0.92±0.5 to 1.18±0.59 mL-1 (p=0.044). Other parameters of diastolic dysfunction were not affected by the device.
Conclusion: Acute FMR was decreased by the application of an epicardial device. Diastolic function was not adversely affected by the device. Most likely, correction of FMR by the epicardial device was achieved by repositioning of the papillary muscles. This was accomplished by application of a device that was not in contact with blood and did not require cardiopulmonary bypass.