Noninvasive measurement of left ventricular end-diastolic pressure and myocardial elasticity by analysis of small vibration on heart wall

Left ventricular (LV) pressure, especially LV end-diastolic pressure, is a significant parameter for the clinical diagnosis of heart diseases. And the elastic modulous of the LV wall has an important role in LV function. In this paper, we noninvasively estimate the LV end-diastolic pressure and the elastic modulus of the LV wall. If we obtain the instantaneous mode-2 eigenfrequency of a small vibration and the average radius and thickness of LV, we can noninvasively estimate the LV end-diastolic pressure and the elastic modulous of the LV wail by combing the Mirsky's method, which evaluates the elastic stiffness of the left ventricle, and our proposed method, which evaluates the LV myocardial elasticity. We transcutaneously measure small vibration signals on the LV wall by ultrasound and calculate the LV instantaneous mode-2 eigenfrequency which is determined from time- frequency distribution by applying the short time Fourier tranform (STFT) to the small vibration on the LV wall. We estimate the LV end-diastolic pressure for four patient, (a) 60-year-old, male, mitral incompetence, (b) 57-year- old, male, dilated cardiomyopathy and myocardial ischemia (inferior), (c) 61- year-old, female, dilated cardiomyopathy, (d) 44-year-old, male, dilated cardiomyopathy. The estimated LV pressure, p(t), is compared with the actual pressure, p(t), which is simultaneously measured by the cardiac catheterization. As a result, we confirmed that we can estimate the LV end- diastolic pressure by bias error, -1.6 mmHg, and the standard deviation, 3.2 mmHg. At the same time, the elastic modulus of the, LV wall is estimated from the chest surface by ultrasound. The results of four patients are, (a) 97 kPa, (b) 36 kPa, (c) 115 kPa, (d) 90 kPa, respectively. And the LV elastic modulous of (e) 25-year-old, male, normal is 26 kPa. The elastic modulus of the LV wall of four patients are higher than that of normal. Although there are several assumptions of our proposed method, we can demonstrate the possibility of noninvasive estimating the LV end-diastolic pressure and elastic modulus of LV wall.