Design and Implementation of Software Platform for AI-ECG Algorithm Research / 中国医疗器械杂志

A software platform for AI-ECG algorithm research is designed and implemented to better serve the research of ECG artificial intelligence classification algorithm and to solve the problem of subjects data information management. Matlab R2019b and MySQL Sever 8.0 are used to design the software platform. The software platform is divided into three modules including data management module, data receiving module and data processing module. The software platform can be used to query and set the subjects information. It has realized the functions of data receiving, signal processing and the display, analysis and storage of ECG data. The software platform is easy to operate and meets the basic needs of scientific research. It is of great significance to the research of AI-ECG algorithm.

Assessment of atrial fibrillation inducibility based on epicardial mapping signals / 生物医学工程学杂志

Atrial fibrillation (AF) is the most common arrhythmia in clinic, which can cause hemodynamic changes, heart failure and stroke, and seriously affect human life and health. As a self-promoting disease, the treatment of AF can become more and more difficult with the deterioration of the disease, and the early prediction and intervention of AF is the key to curbing the deterioration of the disease. Based on this, in this study, by controlling the dose of acetylcholine, we changed the AF vulnerability of five mongrel dogs and tried to assess it by analyzing the electrophysiology of atrial epicardium under different states of sinus rhythm. Here, indices from four aspects were proposed to study the atrial activation rule. They are the variability of atrial activation rhythm, the change of the earliest atrial activation, the change of atrial activation delay and the left-right atrial dyssynchrony. By using binary logistic regression analysis, multiple indices above were transformed into the AF inducibility, which were used to classify the signals during sinus rhythm. The sensitivity, specificity and accuracy of classification reached 85.7%, 95.8% and 91.7%, respectively. As the experimental results show, the proposed method has the ability to assess the AF vulnerability of atrium, which is of great clinical significance for the early prediction and intervention of AF.

Prediction of recurrence of paroxysmal atrial fibrillation based on RR interval / 生物医学工程学杂志

Atrial fibrillation (AF) is one of the most common arrhythmias, which does great harm to patients. Effective methods were urgently required to prevent the recurrence of AF. Four methods were used to analyze RR sequence in this paper, and differences between Pre-AF (preceding an episode of AF) and Normal period (far away from episodes of AF) were analyzed to find discriminative criterion. These methods are: power spectral analysis, approximate entropy (ApEn) and sample entropy (SpEn) analysis, recurrence analysis and time series symbolization. The RR sequence data used in this research were downloaded from the Paroxysmal Atrial Fibrillation Prediction Database. Supporting vector machine (SVM) classification was used to evaluate the methods by calculating sensitivity, specificity and accuracy rate. The results showed that the comprehensive utilization of recurrence analysis parameters reached the highest accuracy rate (95%); power spectrum analysis took second place (90%); while the results of entropy analyses and time sequence symbolization were not satisfactory, whose accuracy were both only 70%. In conclusion, the recurrence analysis and power spectrum could be adopted to evaluate the atrial chaotic state effectively, thus having certain reference value for prediction of AF recurrence.

Rhythm analysis of body surface potential mapping recordings from atrial fibrillation patients based on autocorrelation function / 生物医学工程学杂志

The study of atrial fibrillation (AF) has been known as a hot topic of clinical concern. Body surface potential mapping (BSPM), a noninvasive electrical mapping technology, has been widely used in the study of AF. This study adopted 10 AF patients' preoperative and postoperative BSPM data (each patient's data contained 128 channels), and applied the autocorrelation function method to obtain the activation interval of the BSPM signals. The activation interval results were compared with that of manual counting method and the applicability of the autocorrelation function method was verified. Furthermore, we compared the autocorrelation function method with the commonly used fast Fourier transform (FFT) method. It was found that the autocorrelation function method was more accurate. Finally, to find a simple rule to predict the recurrence of atrial fibrillation, the autocorrelation function method was used to analyze the preoperative BSPM signals of 10 patients with persistent AF. Consequently, we found that if the patient's proportion of channels with dominant frequency larger than 2.5 Hz in the anterior left region is greater than the other three regions (the anterior right region, the posterior left region, and the posterior right region), he or she might have a higher possibility of AF recurrence. This study verified the rationality of the autocorrelation function method for rhythm analysis and concluded a simple rule of AF recurrence prediction based on this method.

Analysis of the Rhythm of Atrial Epicardial Mapping Data Based on Dominant Frequency / 中国医疗器械杂志

If heart function is normal, the atrial cells are excited in a stable rhythm. But this would change during atrial fibrillation. In this paper, after comparing with the method of characteristic point, we use the dominant frequency method to analyze the activation pattern under sinus and atrial fibrillation rhythm in different parts of atria based on epicardial mapping system. It is found that the activation rhythm changes a lot in different parts of atria, and the automaticity of atrial cells change obviously in somewhere. The result shows that dominant frequency method is very suitable for the analysis of atrial fibrillation signal. What's more, we also roughly discuss the role of this method in exploring the driving sources during atrial fibrillation.

The correlation analysis of the epicardial signals by Shannon entropy / 中国医疗器械杂志

This paper applied the Shannon Entropy based on the cross correlation to analyze the epicardial signals from anterior wall of the canine atria. The result demonstrated that during sinus rhythm, the stability level of the correlation among signals from anterior right atria is much higher than the signals from anterior left atria. All the signals from the anterior wall descended when the rhythm changed from sinus rhythm to atrial fibrillation(AF). However, there were some regions still having a stable correlation during AF. The results will be helpful to enhance understanding of the correlation characteristic of AF.

Implementation of 3D heart modeling based on an improved region rowing method / 中国医疗器械杂志

Image segmentation is a key step for image processing. This study developed an improved region growing algorithm to extract the outline of the heart for 3D-modeling which based on the acquisition of canine cardiac CT images from animal experiment. In this paper the method was also compared with the classic algorithm of threshold segmentation. The result showed that the method can be used for the 3D display technology of cardiac electrical activity in clinical electrophysiology mapping.

Design of portable 12-lead digital ECG with low power consumption / 中国医疗器械杂志

The design of portable and low power consumption 12-lead ECG is based on the digital signal processor TMS320C5515 and the analog front end ADS1298. The ADS1298 collects the ECG signals and deliver them to TMS320C5515. The preprocessed ECG signals are displayed real-time on a LCD and can be stored without compression for a long time. The ECG signals can also be sent to an up computer by a USB connector so that ECG data can be analyzed offline. The system has small volume, high precision and low power consumption.

The analysis of atrial cells conductivity based on epicardial mapping data of dog / 中国医疗器械杂志

This paper discusses the law of atrial electrical activity propagation (the timing of signal and the conduction velocity) under the sinus rhythm before and after AF caused by high-frequency electrical stimulation. The paper analyzes how different doses of acetylcholine affect the conductivity of the atrial cells of dogs. This result can also help the diagnoses and treatment of human's AF.

The development for real-time sampling and display in epicardial mapping system / 中国医疗器械杂志

In order to realize real-time sampling and display in 128-channeled Epicardial Mapping System whose sampling frequency is 2 kHz per channel, the article introduces a mapping software and preliminarily validates its practicability. The software is designed in MFC, using multiple-thread technology and buffering and pumping values method.

An adaptive filtering algorithm applied to inhibit the interference from the ventricular during atrial epicardial mapping experiment / 中国医疗器械杂志

This paper introduces an adaptive filtering algorithm based on the LMS principle to inhibit the ventricular interference in the atrial epicardial mapping experiments.

A method of real-time sampling and smooth scrolling in epicardial mapping system / 生物医学工程学杂志

In order to control real-time sampling and achieve smooth scroll wave in the epicardial mapping system, which has 128 channels and a sampling rate of 2kHz/channel, we have designed a user interface using Direct-Draw in cooperation with multiple-thread technology and extracting method. This method has proven to be feasible in animal experiment.

Initial study on the characterization of atrial fibrillation in epicardial mapping / 生物医学工程学杂志

Atrial fibrillation (AF) is a complex and dangerous arrhythmia. The treatment method is still unefficient because of its unknown mechanism. The purpose of our research is to detect the electrical activity on the atria surface and therefore find the optimal technique to characterize AF for clinical application. All kinds of maps are presented clearly and the activity of sinus or AF rhythm can be seen quite differently. The active isopotential map can display the dynamic electrical conduction of the atrium as a movie. Sequentially the vectorgraph shows the direction of depolarization at every moment. Finally statistical results are also very useful for analysis on AF. Statistics of exciting frequency and correlation area show great difference in various channels during AF. "Source" or "sink" may be estimated by interval variance statistics. This study demonstrates the flexibility of the system in AF research. The statistical results can also be adopted to clearly express the characteristics of AF.

A Method for Pretreatment and Character Extraction of Epicardial Signals Based on Template Matching / 航天医学与医学工程

Objective To explore a method for real-time pretreatment and character extraction of epicardial signals and promote the research on the electrophysiological mechanism of atrial fibrillation (AF).Methods Firstly,an analysis was made to get the properties of epicardial signals. Then,a method based on template matching was used to extract atrial activities from epicardial signals. At last,the feature points of atrial activities could be recognized.Results The correctness of recognizing feature points of sinus rhythm and AF were 99.7% and 97.0% respectively. Furthermore,only 1~2 s were cost to compute a 10-second data record with this method.Conclusion The proposed method can extract crucial information about atrium depolarization from epicardial signals and is adequate for online analysis.

Model Reseach of Effects of Defibrillation Waveform on Action Potential Duration / 航天医学与医学工程

Objective To explore the mechanism underlying the superiority of the biphasic waveform to monophasic waveform in defibrillation.Method The Luo-Rudy model was adjusted so that it could be used to study defibrillation.Based on the adjusted model the effects of different defibrillation waveforms on cell action potential duration(APD) were studied.Result Biphasic electrical field pulse extended the APD longer than that with monophasic one.Moreover,biphasic waveforms with different strengths could prolong the APD almost equally,while monophasic pulses with different strengths showed different ability to prolong the APD and the spatial distribution of the APD became dispersed.It was also found that the strength of electrical fields pulse contributed much to the change of APD while the duration showed little effect.Conclusion The clinical superiority of biphasic pulses to monophasic pulses in defibrillation is resulted from its ability to prolong the time course of the APD and more importantly,it causes even spatial distribution of the APD.

Correlation Analysis of Epicardial Depolarization Wave Based on Combined Unipolar and Bipolar Mapping Technique / 航天医学与医学工程

Objective To find a method for real-time measurement of epicardial electrical activity suitable for clinical application.Method Combined unipolar and bipolar mapping technique for recording epicardial electrical activity was applied to detect the propagation of depolarization wave over the epicardium.Epicardial signals from 4 pigs were sampled simultaneously during sinus rhythm or atrial fibrillation(AF).Result Active isopotential map showing the spread of excitation on epicardial surface was demonstrated and correlation analysis data were obtained.The difference in correlation coefficients between adjacent sites was evident during sinus rhythm(above 0.8) and AF(about(0.5).) Conclusion The result shows that combined unipolar and bipolar technique improves the electrode efficiency and the precision in epicardial mapping.Distribution of depolarization wave or the reentry pathway during complex arrhythmia may be revealed by correlation analysis.

Fitting APD Restitution with Artificial Neural Network / 航天医学与医学工程

Objective To study the complex restitution relation between the present action potential duration (APD) and its previous diastole interval (DI) and APD. Method The Luo-Rudy model was paced with different protocols to draw the coordinate curves between the present APD and its first previous DI. These curves were fit with the artificial neural network (ANN). Result Different pacing protocols caused different coordinate curves, and there was no one-to-one relation between pre-sent APD and its first previous DI. ANN fits these curves satisfactorily. Conclusion There is a complex relation between the present APD and the APDs and Dis of the first three previous beats. This relation can be modeled accurately with ANN.

The study of EEG telemetry technology / 中国医学物理学杂志

This Paper brings forward a new technology of EEG Telemetry. Using two FDM channels, the signals can be transmitted through public telephone lines: the EEG signals are transmitted by TDM technology in one channel; the parametes are transmitted to the receiver for identification of data or synchronization in the other channel synchronously. This technology can satisfy almost any routine clinic needs, and also the quahty of transmission is nearly perfect: the distortion is little; distinct noise pollution and shift of base-line do not exist, which is valuable in medical application.