Assessment Of Cardiovascular Function Based On Pulse Wave Analysis Of Radial Artery

Artery stiffness is the pathophysiological basis of cardiovascular disease. Early detection and intervention of artery stiffness, therefore, is the essential way to prevent cardiovascular disease. Determination of hemodynamic parameters using PWA is a commonly used method for assessing artery stiffness. The study on the method was started very early in foreign countries and several representative indicators for assessing cardiovascular function have been proposed. For example, aoPWV obtained by two-site measurement is a gold standard of arterial stiffness, and SEVR derived from central pressure is widely accepted as a means of myocardial perfusion. Detecting devices based on these achievements have been used in large hospitals as tools for diagnosis of cardiovascular disease and assessment of treatment effect, including Complior (Artech Medical, Pantin, France), SphygmoCor (AtCor Medical, Sydney, Australia) and HEM-9010AI (Omron Healthcare Co. Ltd., Kyoto, Japan). However, the use of them is limited in the field of public health, as they are expensive and complicated to operate, in addition to the need for skilled operating techniques. Therefore, it is necessary to establish new methods and technologies for assessing artery stiffness suitable for group screening and dynamic detection of individuals. In order to meet the demand, in this thesis, the studies on assessment of cardiovascular function using PWA of radial pulse waveform are made as follows:1. Construction of evaluation index systemBased on research and development of the field, an evaluation index system is established first, according to the principles such as clear physiological significance and strong practical. Indexes for assessing arterial function (such as PTT and aoPWV) and indexes for assessing cardiac function (such as HR and SEVR) are included. All of these indexes are derived by PWA of radial pressure waveform, which are suitable for group screening and dynamic detection of individuals.2. Study on measurements of key indicators With regard to the measurements of PTT, aoPWV and SEVR in the evaluation index system, the following studies and corresponding research achievements are made, which enriches and develops the theory of wave propagation.(1) Measurement of PTTWe propose a novel noninvasive method to obtain PTT from a single radial pressure waveform. Radial pulse waveform is easily recorded using applanation tonometry, the first and second systolic peaks of which are automatically detected using PWA. The time interval between them is calculated to estimate PTT. A total of266healthy adults are included in the study, among which PTT obtained using the new method is significantly highly corrected with age. Therefore, the simple and easily obtainable PTT is suggested as a useful index of arterial stiffness.(2) Measurement of aoPWV Based on the study of PTT, a new method is proposed consequently to calculate aoPWV using PWA of radial pulse waveform. The navel is selected as the surface measurement point of the major reflection site, and aoPWV is calculated as the length between navel and suprasternal notch divided by PTT. In46young and middle-aged healthy humans, there is a strong correlation between aoPWV obtained by the method and cfPWV obtained by Complior with no significant difference. Additional, good week-to-week reproducibility is found. These results suggest that the method has potential to detect premature arterial aging for the management of primary prevention.(3) Validation of determining SEVR from radial arteryIn231individuals including healthy and hypertensive subjects, carotid and radial SEVR are obtained from the simultaneously recordings of radial and carotid pulse waveforms, and the relationship between them is investigated. Radial SEVR is significantly correlated with carotid SEVR in the study population. They have consistent independent predictors. Additional, changes in radial SEVR with aging corresponds to changes in carotid SEVR. Therefore, SEVR obtained directly from radial pressure wave could provide equivalent information to central SEVR.3. Design, implementation and validation of the prototype detection systemBased on the methods and technologies proposed in our studies, we design and implement prototype detection system, including automatic device for self-measurement of cardiovascular function (IIM-2010A; Institute of Intelligent of Machines, Hefei, China) and multi-function device for signal acquisition and analysis. Radial pulse waveform is recorded using applanation tonometry (IIM-2010A). BP measured at radial artery is used to calibrate radial tonometric pulse waveform. Feather points are detected automatically using PWA, and then used to calculate hemodynamic characteristics, which is suitable for group screening and dynamic detection of individuals. The multi-function device can record multi-channel pulse waveforms, BP of four limbs, ECG and photoelectric signals simultaneously. It provides experimental condition for future research.We compare IIM-2010A against the widely accepted devices (SphygmoCor and HEM9001AI) in57healthy subjects. A good agreement in calculating AI and SEVR and short-term reproducibility of the three devices suggest that, the new tonometric device IIM-2010A is suitable for assessing cardiovascular function, and provides a simply obtainable and low cost solution for early detection of artery stiffness.