航天医学与医学工程

目的 较高的运动负荷强度与严重的噪声干扰容易导致心电信号质量变差。低质量信号容易引起误报警、监护不力、评估不准确甚至诊断错误。心电信号质量的定量评估是实现自动化的心电降噪与心脏疾病诊断的基础。方法 本研究分别对心拍形态相似性、心电斜率特征进行统计分析，得到基于相似性的信号质量指数（rSQI）与基于斜率的信号质量指数（kSQI）。结果 经MIT-BIH噪声干扰数据库测试，rSQI与kSQI均随心电信噪比的降低而减小，均能够反映心电信号质量。心拍形态相似性基于心电波形的“准周期”特性，通过互相关方法计算，运算量大，但精度高，且为逐拍参数；斜率法不需要QRS波群检测，斜率计算简单且实时性高，但其灵敏性低于相似法，且为统计参数。结论 两种方法均适于心电信号质量的定量评估；斜率法的优势在于简单、计算方便，但相似法更准确、稳健。

Objective Electrocardiogram(ECG) signal quality degrades when the level of activity is high and motion artifacts are severe. Poor quality signals may result in false alarms, poor patient monitoring, imprecise measurement, and misleading diagnosis. The quantitative assessment of ECG signal quality forms the basis of automatic ECG noise reduction and heart disease diagnosis. Methods The ECG signal quality index(SQI) was obtained by statistically analyzing the heartbeat similarity and the slope character, respectively, namely rSQI and kSQI. Results Using MIT-BIH Noise Stress Test Database to test, both rSQI and kSQI decreased when the Signal Noise Ratio(SNR) decreased, which revealed the ECG signal quality. Based on the quasiperiodic property, the waveform similarity, as a beat-to-beat index, is obtained by cross correlation between two ECG cycles with high precision but heavy computation. Slope-based method dispenses with QRS detection and is very simple and real-time, but its sensitivity is lower than similarity-based method and it only get statistical data. Conclusion Both morphology similarity and slope character algorithms could provide objective estimation of ECG quality. Slope-based method is an attractive measure due to its simplicity and mathematical convenience, while similarity-based method is more accurate and robust for ECG quality assessment.