Noninvasive measurement of left ventricular myocardial elasticity

We examined Advani and Lee's equation (ALeq) and a dimension analysis-derived equation (DAeq), both of which treat vibration of the elastic spherical shell and are able to estimate elasticity of the shell noninvasively when the sizes and eigen-frequency are provided. We confirmed that ALeq was numerically identical to DAeq and that both equations gave the precise elasticity of the silicone shell. Then we estimated left ventricular (LV) myocardial elasticity noninvasively at the moment of the first heart sound emission (1HS) in 25 healthy subjects and 14 hypertrophic cardiomyopathy (HCM) patients, based on the LV eigen-frequency detected by an intraesophageal miniature vibration sensor. HCM patients had a higher mean value of LV myocardial elasticity at 1HS than healthy subjects [102.3 +/- 33.4 vs. 70.7 +/- 24.4 kPa, P < 0.01 (Pa = N/m2 = 10 dyn/cm2)]. We thereby demonstrated the possibility of a noninvasive estimate of myocardial elasticity.