Shearwave dispersion ultrasound vibrometry applied to in vivo myocardium

Diastolic properties of the myocardium are important for normal cardiac function and may contribute to the condition of heart failure. Measuring the viscoelastic properties of the left ventricular myocardium is difficult in vivo using noninvasive methods. In this study, we used a mechanical actuator to create harmonic, propagating mechanical waves in the myocardial tissue in vivo. The motion was measured using ultrasound imaging techniques. The wave propagation velocities were measured over the 50-350 Hz frequency range. The dispersion curves were fit with an asymmetrical Lamb wave model to obtain estimates of the shear elasticity and viscosity of the myocardial tissue. The method was applied to estimate viscoelastic properties of the myocardium during diastole and systole.