Development of Noninvasive Ultrasonic Measurement Device for Visco-elastic Properties of Vessel Wall

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To measure noninvasively the elastic properties of in vivo human arteries including deep aorta, which had not been able to be measured hitherto, a new echo tracking device linked to cross-sectional echography was deyeloped. The accuracy of the device for pulsatile diameter change( <delta> D) was <10^(-3)> mm and for diameter(D) was around 0.5mm respectively, and was sufficient to measure the visco-elastic properties of arterial wall. The pressure strain elastic modulus (Ep) of the abdominal aorta were noninvasively measured in 61 healthy subjects(20-89 years) with this ultrasonic device from <delta> D, D and blood pressure obtained by auscultatory method. The mean Ep value was 2.1 x <10^6> dyne/ <cm^2> . Ep was significantly increased with age(p<0.001), The regression equation relating Ep to age was Ep=(-0.72+0.058 x age)x <10^6> dyne/ <cm^2> (r=0.73). In the systemic measurement of elastic properties in arterial tree from aorta to brachial and popliteal artery in 4 healthy subjects, t … More he elevation of Ep value was found in the peripheral site of the artery. In the measurement of age-matched 42 healthy subjects and 32 patients with coronary artery disease(CAD)(40-60 years), Ep was 0.99 and 1.83 x <10^6> dyne/ <cm^2> respectively. A significant sclerotic change(p<0.001) was found also in the abdominal aorta in CAD patients compared with normal subjects. A significant correlation(p<0.01) between Ep value and the value of blood total cholesterol was found in the CAD patients. Accelerating factor like a coronary risk factor was suspected to influence also the progression of aortic sclerosis. Furthermore, with the device and the additional use of catherter tip micromanometer for blood pressure measurement, visco-elastic properties of aorta in vivo were obtained in 14 subjects from the area of the hysteresis loop in the pressure-radius relationship with computer system. Coefficient of viscosity( <eta> ) 2.34 x <10^4> dyne.s/ <cm^2> , viscous loss modulus( <eta> <omega> ) 1.83 x <10^6> dyne/ <cm^2> , and phase angle( <phi> ) 0.087 radian, Ep 2.02 x <10^6> dyne/ <cm^2> were obtained. Less