建構多功能心電圖模擬器

Construction of multi-function ECG simulator

林偉淳(Wei-Chun Lin)

指導教授 ： 徐良育

中原大學/工學院/生物醫學工程研究所/碩士(2011年)

https://doi.org/10.6840/cycu201101119

摘要

本研究之目的即利用微處理器發展一套多功能心電圖訊號模
擬器，可重複播放所需的訊號以提供研究與教學之用，本模擬器除了
能夠量測標準導程之心電圖、由使用者輸入不同心率之正常心電圖及
P-R interval 和Q-T interval 在不同心率之變化外，也能模擬藉由改變
心率變異度(heart rate variability)的頻域參數，如：低頻及高頻的比值
(LF/HF)、低頻中心(0.04-0.15Hz)、高頻中心(0.15-0.4Hz)，輸出具有心
率變異(R-R interval 變化)之心電圖。
在心率變異頻譜圖模擬部份，因考慮到處理器的速度以及運算限
制，本研究使用離散序列方式來取代運算量龐大的連續方法，再將離
散以及連續方法的結果做比較。離散序列主要是由數個sin 波組成，
sin 波組成的結果即為時域序列，並由此時域序列取得R-R 間期。而
連續方法則是須將連續頻譜做快速傅立葉反轉換算出時域序列。再取
得R-R 間期。利用上述兩種方法取得之R-R 間期建構的ECG 訊號再
進一步做一般的心率變異度頻譜分析，包括了R 波檢測、重新取樣、
快速傅立葉轉換(FFT)，並做比較。此外，也會將MSP430 計算出的
R-R 間期與Matlab 計算的R-R 間期做比較。

結果與驗證顯示，在離散以及連續兩種方式的頻譜比較，高、低
頻中心沒有差異，LF/HF 比值經t-test 比較兩者是沒有顯著差異
(P>0.05)。在MSP430 與Matlab 計算的R-R 間期的比較則有統計上顯
著差異(P<0.05)。影響誤差主要原因有二，一、MSP430 無法做浮點數
運算；二、MSP430 的sin 波是使用建表的方式，若增加頻率會有誤
差，這些誤差日後需再以修正。本研究結果證明，使用離散方式建構
之心電圖取代連續方式是可行的，模擬器亦可任意改變心率變異頻譜
參數來模擬不同R-R 間期之心電圖。

關鍵字

心電圖模擬器 ； 心率變異度 ； 心電圖

並列摘要

Abstract
The purpose of this study is to develop a multi-functional ECG simulator using micro-processor, it can product ECG signal to be used for research and teaching. The simulator can not only measure ECG、display the normal-ECG by entering different heart rate, the P-R interval and Q-T interval can vary with different heart rate, but also can simulate the ECG with heart rate variability(HRV), by changing the parameters of HRV, such as low-frequency and high frequency ratio (LF/HF), low frequency center(0.04-0.15Hz), high frequency center (0.15-0.4Hz).
In the simulation of the spectrum of heart rate variability, due to the limitation of speed and computing capability of microprocessor, discrete sequences were used to replace the continuous method. Results of these two method were then compared. The discrete sequence is composed of several sine-wave, the combination result of these sine waves is a time
domain sequence that, R-R intervals can be obtained from. On the other hand, the continuous methods need to inverse fast Fourier transform to obtain the time domain sequence then all R-R interval can be obtained. The ECG signals onstructed using these R-R interval were then subject to the regular procedure for heart rate variability spectrum analysis to compare the R-R interval of those two methods. The procedure includes the R-wave detection, re-sampling, fast Fourier transform(FFT). In addition, the R-R interval calculated by MSP430 were compared with those calculated using MATLAB.
The results demonstrate that these is no different in low and high frequency center between continuous and discrete methods. The LF/HF ratio shows no significant different (P>0.05). However, there is significant different (P<0.05) in R-R interval obtained by MSP430 and MATLAB.
There are two major reasons contribute to this error, one is the MSP430 can’t compute floating point; another reason is the sin wave of MSP430 are constructed by table, increase the frequency of simulated sine wave introduce larger error, those error need to improve in the future. The outcome proves that the continuous method can be replaced by the discrete methods, and the simulator can change the parameter of heart rate variability to simulate ECG with different R-R interval.

並列關鍵字

Heart Rate Variability ； Electrocardiogram ； ECG simulator

參考文獻

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