Viscoelasticity measurement of heart wall in in vivo

By measuring the spatial distribution of the minute vibrations in the heart wall from the chest wall using ultrasound, we find that some impulses propagate along the heart wall in healthy human subjects just after closure of the aortic valve for the first time. Their amplitude is found to be on the order of several tens of micrometers, and up to 100 Hz. Their propagation speed shows frequency dispersion, which agrees with the theoretical characteristics of the Lamb wave. The instantaneous viscoelasticity of the wall is then noninvasively determined. These findings have a novel potential for myocardial tissue characterization in clinical diagnosis.