Department of Electrical Engineering, Eindhoven University of Technology, 5612 AZ, Eindhoven, Netherlands. Philips Research, Eindhoven, Netherlands.
Physiol Meas. 2018 Aug 8;39(8):084001. doi: 10.1088/1361-6579/aad2c0.
Atrial fibrillation (AF) is the most commonly experienced arrhythmia and it increases the risk of stroke and heart failure. The challenge in detecting the presence of AF is the occasional and asymptomatic manifestation of the condition. Long-term monitoring can increase the sensitivity of detecting intermittent AF episodes, however it is either cumbersome or invasive and costly with electrocardiography (ECG). Photoplethysmography (PPG) is an unobtrusive measuring modality enabling heart rate monitoring, and promising results have been presented in detecting AF. However, there is still limited knowledge about the applicability of the PPG solutions in free-living conditions. The aim of this study was to compare the inter-beat interval derived features for AF detection between ECG and wrist-worn PPG in daily life.
The data consisted of 24 h ECG, PPG, and accelerometer measurements from 27 patients (eight AF, 19 non-AF). In total, seven features (Shannon entropy, root mean square of successive differences (RMSSD), normalized RMSSD, pNN40, pNN70, sample entropy, and coefficient of sample entropy (CosEn)) were compared. Body movement was measured with the accelerometer and used with three different thresholds to exclude PPG segments affected by movement.
CosEn resulted as the best performing feature from ECG with Cohens kappa 0.95. When the strictest movement threshold was applied, the same performance was obtained with PPG (kappa = 0.96). In addition, pNN40 and pNN70 reached similar results with the same threshold (kappa = 0.95 and 0.94), but were more robust with respect to movement artefacts. The coverage of PPG was 24.0%-57.6% depending on the movement threshold compared to 92.1% of ECG.
The inter-beat interval features derived from PPG are equivalent to the ones from ECG for AF detection. Movement artefacts substantially worsen PPG-based AF monitoring in free-living conditions, therefore monitoring coverage needs to be carefully selected. Wrist-worn PPG still provides a promising technology for long-term AF monitoring.
心房颤动（AF）是最常见的心律失常，它会增加中风和心力衰竭的风险。检测 AF 存在的挑战在于该病症偶尔出现且无症状。长期监测可以提高间歇性 AF 发作的检测灵敏度，但心电图（ECG）监测既繁琐又具有侵入性，且成本高昂。光体积描记法（PPG）是一种非侵入性测量方式，可实现心率监测，并且在检测 AF 方面已经取得了有前景的结果。然而，关于 PPG 解决方案在自由生活条件下的适用性，人们的了解仍然有限。本研究的目的是比较 ECG 和腕戴式 PPG 在日常生活中用于 AF 检测的间期特征。
数据包括 27 名患者（8 名 AF，19 名非 AF）的 24 小时 ECG、PPG 和加速度计测量值。总共比较了 7 种特征（香农熵、均方根差的连续差异（RMSSD）、归一化 RMSSD、pNN40、pNN70、样本熵和样本熵系数（CosEn））。使用加速度计测量身体运动，并使用三个不同的阈值来排除受运动影响的 PPG 段。
CosEn 是 ECG 中表现最好的特征，Cohen's kappa 为 0.95。当应用最严格的运动阈值时，PPG 也获得了相同的性能（kappa=0.96）。此外，pNN40 和 pNN70 在相同的阈值下达到了类似的结果（kappa=0.95 和 0.94），但对运动伪影更稳健。与 ECG 相比，PPG 的覆盖范围取决于运动阈值，在 24.0%-57.6%之间，而 PPG 的覆盖范围为 92.1%。
PPG 衍生的间期特征与 ECG 用于 AF 检测等效。运动伪影会极大地恶化自由生活条件下基于 PPG 的 AF 监测，因此需要仔细选择监测覆盖范围。腕戴式 PPG 仍然是长期 AF 监测的有前途的技术。
