In-vivo transducer to measure dynamic mitral annular forces.

Limited knowledge exists regarding the forces which act on devices implanted to the heart's mitral valve. Developing a transducer to measure the peak force magnitudes, time rates of change, and relationship with left ventricular pressure will aid in device development. A novel force transducer was developed and implanted in the mitral valve annulus of an ovine subject. In the post-cardioplegic heart, septal-lateral and transverse forces were continuously measured for cardiac cycles reaching a peak left ventricular pressure of 90 mmHg. Each force was seen to increase from ventricular diastole and found to peak at mid-systole. The mean change in septal-lateral and transverse forces throughout the cardiac cycle was 4.4±0.2 N and 1.9±0.1 N respectively. During isovolumetric contraction, the septal-lateral and transverse forces were found to increase at peak rate of 143±8 N/s and 34±9 N/s, respectively. Combined, this study provides the first quantitative assessment of septal-lateral and transverse forces within the contractile mitral annulus. The developed transducer was successful in measuring these forces whose methods may be extended to future studies. Upon additional investigation, these data may contribute to the safer development and evaluation of devices aimed to repair or replace mitral valve function.