Extravascular and Intravascular Continuous Blood Pressure Measurements by Ultrasound

• Main Authors: Shang-Ju Lee, 李尚儒
• Other Authors: 李百祺
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/ss2pq9

碩士 === 國立臺灣大學 === 生醫電子與資訊學研究所 === 107 === Cardiovascular disease (CVD) has been the second leading cause of death in Taiwan in recent years. One of the most crucial issues of CVD is coronary atherosclerosis. When atherosclerosis causes significant stenosis or rupture of atherosclerotic plaque, acute thrombosis may occur and further increase the cardiovascular risk. The blood pressure can be measured extravascularly for cardiovascular disease assessment. In addition, the changes in intravascular blood pressure can also provide an assessment of the condition of arterial plaque. To this end, the primary purpose of this study is to develop extravascular and intravascular methods for continuous blood pressure measurements. In the extravascular experiments, ultrafast imaging was applied and a phase tracking method was developed to estimate the pulse wave velocity (PWV). Finally, the continuous blood pressure waveform can be estimated after considering the PWV and the elasticity properties of the blood vessel. The proposed method was tested both in vitro and in vivo. On human carotid arteries, it was demonstrated that the error was within 3 mmHg compared with that obtained from a commercial instrument. For the intravascular experiments, both numerical simulations and phantom experiments using intravascular ultrasound (IVUS) were performed. Results showed a positive correlation between the flow velocity and the signal decorrelation rate. After linear regression, the fitted velocity can be used to estimate the flow velocity and then the flow reserve fraction (FFR) based on the calculation of the pressure loss of a fluid flowing through different cross-sectional areas in the blood vessel. The error of pressure in this particular experiment was below 5mmHg. The intravascular and extravascular blood pressure measurements we proposed are limited by the hypothesis of pressure equations, unlike clinical used directly measuring instruments, there are many limitations and still need to been proved the feasibility in clinical application through a large number of human experiments.