Evaluation of left atrial wall elasticity using acoustic microscopy

Left atrial wall elasticity is one of the important factors regulating left atrial stiffness and functions. The authors evaluated left atrial wall ela sticity by measuring the sound speed through the left atrial wall, based on the hypothesis that high elasticity tissues will yield larger sound speed values through the tissue, and examined age-associated changes in left atri al wall elasticity. Left atrium specimens were obtained from 30 normal subj ects (age, 15-95 years) at autopsy. An acoustic microscope, operating at 45 0 MHz, was used to measure the sound speed in the endocardium and the myoca rdium of the left atrium. The sound speeds in endocardium and myocardium de monstrated significant correlation with age (r = 0.74, p < 0.0001 and r = 0 .47, p < 0.01, respectively), These findings indicate that left atrial wall elasticity increased with advancing age. These changes may lead to deterio ration of left atrial compliance and eventual left atrial failure in older subjects.