心電圖移動雜訊即時抑制之最佳化

Abstract

近年來，人們飲食習慣的改變使得心臟病已經成為現代人的一大威脅，其中缺血性心臟病更是全球致死率最高的疾病，主要是由於其缺乏早期徵兆，而臨床上最用來早期診斷出缺血性心臟病最重要的工具之一為運動心電圖，因為運動心電圖可藉由運動使心臟的需氧量變大，藉以反映出供應氧氣的能力來判斷血管是否有粥狀硬化的現象，比起一般心電圖，可診斷出更早期的缺血性心臟病。 然而，運動心電圖若受到移動雜訊的影響，會造成心電訊號振幅的改變，進而造成基線有嚴重漂移的現象，使得醫護人員無法確切的診斷疾病，且此雜訊影響的頻帶剛好與心電訊號的頻率重疊，故要將此雜訊消除且保留完整心電訊號是相當困難的事。 本研究主要目的為消除移動雜訊，並保留無失真的心電訊號，故我們將消除過程分為硬體與軟體兩部分，先藉由硬體架構將移動雜訊消除，但由於頻帶的重疊，使得在消除移動雜訊的同時，部分心電訊號跟著也被消除而失真，因此，我們透過軟體擷取出原始心電訊號中的P波、QRS波和T波，並以硬體處理後之心電訊號的基線和原始訊號的波形重組成一個完整的心電訊號。 期許本系統未來可實際用來消除運動心電圖的移動雜訊，幫助醫療人員更準確的判斷出早期缺血性心臟病的徵兆，使病患能及時接受治療。

Heart disease has become a serious problem for human because of diet. According to World Health Organization, ischemic heart disease causes the highest death rate due to lack of early symptoms. Therefore, one of the most important diagnostic tools for clinic is exercise ECG. Because the oxygen demand of heart increases through exercising, exercise ECG can show the characteristics of myocardial ischemia if the oxygen supply is not enough. As a result, exercise ECG can help doctor to diagnose ischemic heart disease early. The motion artifacts, which combine with exercise ECG during measurement, cause misdiagnosis because it change amplitude of waveform and would lead to serious baseline wander. Furthermore, the motion artifacts is hard to suppress since its spectrum completely overlaps with ECG. The aim of this study is to suppress the motion artifacts and to reserve ECG without distortion. First, we propose a hardware circuit to eliminate motion artifact and get a flat baseline. However, the part of ECG also eliminate because the spectrum completely overlaps. Therefore, we extract the shape of P, QRS, and T wave from raw ECG. Finally, we reconstruct ECG by using the flat baseline and the waveform which we extract from raw ECG. We honestly hope the system we implement in this study could be helpful in early diagnosis ischemic heart disease, so that patients can be treated timely.