Inferring ECG from PPG for Continuous Cardiac Monitoring Using Lightweight Neural Network

TL;DR

This study introduces a lightweight neural network that infers ECG signals from PPG data collected by wearables, enabling continuous cardiac monitoring without active user participation and aiding in cardiovascular disease screening.

Contribution

The paper presents a novel, diagnosis-oriented neural network model that accurately reconstructs ECG from PPG signals, facilitating long-term, passive cardiac health monitoring.

Findings

High fidelity ECG reconstruction from PPG signals

Model captures pathological features relevant to CVD screening

Effective in real-world ambulatory scenarios

Abstract

This paper presents a computational solution that enables continuous cardiac monitoring through cross-modality inference of electrocardiogram (ECG). While some smartwatches now allow users to obtain a 30-second ECG test by tapping a built-in bio-sensor, these short-term ECG tests often miss intermittent and asymptomatic abnormalities of cardiac functions. It is also infeasible to expect persistently active user participation for long-term continuous cardiac monitoring in order to capture these and other types of cardiac abnormalities. To alleviate the need for continuous user attention and active participation, we design a lightweight neural network that infers ECG from the photoplethysmogram (PPG) signal sensed at the skin surface by a wearable optical sensor. We also develop a diagnosis-oriented training strategy to enable the neural network to capture the pathological features of ECG, aiming to increase the utility of reconstructed ECG signals for screening cardiovascular diseases (CVDs). We also leverage model interpretation to obtain insights from data-driven models, for example, to reveal some associations between CVDs and ECG/PPG and to demonstrate how the neural network copes with motion artifacts in the ambulatory application. The experimental results on three datasets demonstrate the feasibility of inferring ECG from PPG, achieving a high fidelity of ECG reconstruction with only about 40K parameters.