Application Study Of Noninvasive Photoelectric Detection On Myocardial Infarction

Myocardial infarction(MI)is an acute and critical disease caused by myocardial ischemia and results in an irreversible loss of cardiac function.The mortality and the morbidity of rural areas in China are increasing,which has become one of the most important diseases causing death and disability globally.Detection of cardiac markers,electrocardiogram,coronary angiography and other means of clinical MI diagnosis still have some shortcomings,such as not timely,insensitive,high-cost and high-risk.Therefore,the study of rapid,non-invasive and reliable MI detection technology and indicators has great significance in clinical application.Based on non-invasive photoelectric detection technology,a new frequency domain analysis method,Linear Amplitude Spectrum(LAS),is proposed to analyze heart rate variability(HRV)in MI patients.By LAS algorithm,HRV indicators of LF and HF are acquired by ECG and photoplethysmography(PPG)of MI patients to evaluate cardiac sympathetic/vagal activity intensity,which is applied in antidiastole of MI patients and healthy people.In addition,Monte-Carlo’s mathematical method was used to simulate the photons migration in thoracic tissues to explore the feasibility of direct detection of abnormal myocardial blood supply by non-invasive photoelectric technology.The results demonstate that 1)the formula of LAS was deduced and proved,and the property was verified by simulating HRV signals,and LAS’s indicators of LF and HF at high and low frequencies in HRV analysis of LF and HF were determined;2)The resting basal state experiment of 35 healthy people confirmed the superiority of LAS’s indicators,and the excellent performance of LAS was tested by the music auditory stimulation experiment.3)A 200 cases randomized controlled study between MI and normal people found that HRV parameters based on ECG of MI patients were all lower than those of normal group for the first time that revealed that the cardiac autonomic nervous activity of MI patients decreased comprehensively.4)A randomized controlled trial was conducted in 30 MI patients and 48 healthy people.The indexes of LF and HF in MI patients were significantly lower than those in the control group by ECG and PPG.The results were consistent with those of the above trial.It was verified that there was a strong linear correlation of cardiac cycle time interval collected by ECG and PPG,which demonstrated that photoelectric detection for HRV could replace ECG under certain conditions.5)Monte-Carlo mathematical method was used to simulate photons migration in human thoracic tissues.It is the first time to quantify and visualize the distribution of photons in thoracic tissue in theory,confirming that photons can reach the myocardium and be detected on the body surface.Based on non-invasive photoelectric detection technology,this study carries out innovative and applied research work on new HRV analysis methods and new HRV indicators reflecting MI cardiac autonomic nervous activity through ECG and PPG.Non-invasive,fast and reliable methods and indicators have been proposed for MI clinical examination.In addition,the feasibility of direct detection of cardiac hemodynamic changes is verified by photon transport simulation in heart tissue,which provides a new research idea for non-invasive,direct and in vivo real-time monitoring and evaluation of myocardial blood supply.