Pinheiro N, Couceiro R, Henriques J, Muehlsteff J, Quintal I, Goncalves L, Carvalho P
Annu Int Conf IEEE Eng Med Biol Soc. 2016 Aug;2016:2945-2949. doi: 10.1109/EMBC.2016.7591347.
Heart rate variability (HRV) represents one of the most promising markers of the autonomic nervous system (ANS) regulation. However, it requires the acquisition of the ECG signal in order to reliably detect the RR intervals, which is not always easily and comfortably available in personal health applications. Additionally, due to progress in single spot optical sensors, photoplethysmography (PPG) is an interesting alternative for heartbeat interval measurements, since it is a more convenient and a less intrusive measurement technique. Driven by the technological advances in such sensors, wrist-worn devices are becoming a commodity, and the interest in the assessment of HRV indexes from the PPG analysis (pulse rate variability - PRV) is rising. In this study, we investigate the hypothesis of using PRV features as surrogates for HRV indexes, in three different contexts: healthy subjects at rest, healthy subjects after physical exercise and subjects with cardiovascular diseases (CVD). Additionally, we also evaluate which are the characteristic points better suited for PRV analysis in these contexts, i.e. the PPG waveform characteristic points leading to the PRV features that present the best estimates of HRV (correlation and error analysis). The achieved results suggest that the PRV can be often used as an alternative for HRV analysis in healthy subjects, with significant correlations above 82%, for both time and frequency features. Contrarily, in the post-exercise and CVD subjects, time and (most importantly) frequency domain features shall be used with caution (mean correlations ranging from 68% to 88%).
心率变异性（HRV）是自主神经系统（ANS）调节中最具前景的指标之一。然而，为了可靠地检测RR间期，需要采集心电图信号，而在个人健康应用中，这并不总是能轻松且舒适地实现。此外，由于单点光学传感器的发展，光电容积脉搏波描记法（PPG）成为心跳间期测量的一种有趣替代方法，因为它是一种更便捷且侵入性更小的测量技术。受此类传感器技术进步的推动，腕戴式设备正成为一种商品，并且通过PPG分析评估HRV指标（脉率变异性 - PRV）的兴趣也在增加。在本研究中，我们在三种不同情况下研究使用PRV特征作为HRV指标替代物的假设：静息状态下的健康受试者、体育锻炼后的健康受试者以及患有心血管疾病（CVD）的受试者。此外，我们还评估在这些情况下哪些特征点更适合PRV分析，即导致PRV特征且能对HRV进行最佳估计（相关性和误差分析）的PPG波形特征点。所取得的结果表明，在健康受试者中，PRV通常可作为HRV分析的替代方法，时间和频率特征的显著相关性均高于82%。相反，在运动后和患有CVD的受试者中，应谨慎使用时间和（最重要的）频域特征（平均相关性在68%至88%之间）。
