Abstract: Deep learning has been widely applied in the field of electrocardiogram (ECG) signal analysis due to its powerful data representation capability. However, supervised methods require a large amount of labeled data, and ECG data annotation is typically time-consuming and costly. Additionally, supervised methods are limited by the finite data types in the training set, resulting in limited generalization performance. Therefore, how to leverage massive unlabeled ECG signals for data mining and universal feature representation has become an urgent problem to be addressed. Self-supervised learning (SSL) is an effective approach to address the issue of missing annotated ECG data and improve the transfer ability of the model by learning generalized features from unlabeled data using pre-defined proxy tasks. However, existing surveys on self-supervised learning mostly focus on the domains of images or temporal signals, and there is a relative lack of comprehensive reviews on self-supervised learning in the ECG domain. To fill this gap, this paper provides a comprehensive review of advanced self-supervised learning methods used in the field of ECG. Firstly, a systematic summary and classification of self-supervised learning methods for ECG are presented, starting from two learning paradigms—contrastive and predictive. The basic principles of different categories of methods are elaborated, and the characteristics of each method are analyzed in detail, highlighting the advantages and limitations of each approach. Subsequently, a summary is provided for the commonly used datasets and application scenarios in ECG self-supervised learning, along with a review of data augmentation methods frequently applied in the ECG domain, offering a systematic reference for subsequent research. Finally, an in-depth discussion is presented on the current challenges of self-supervised learning within the ECG field, and future directions for the development of ECG self-supervised learning are explored, providing guidance for subsequent research in the field.

Key words: electrocardiogram (ECG), feature representation, deep learning, self-supervised learning

摘要： 深度学习因其强大的数据表征能力已被广泛应用于心电（ECG）信号分析领域，但有监督方法的训练过程需要大量标签，而心电数据标注通常是耗时且成本高昂的。且有监督方法受限于训练集中有限的数据类型，泛化性能有限。因此，如何利用海量无标记心电信号进行数据挖掘和通用特征表示已成为亟待解决的问题。自监督学习（SSL）通过预先设置的代理任务从无标签数据中学习泛化特征来提升模型的特征表示能力，是一种解决心电数据标注缺失问题和提升模型迁移能力的有效途径。然而，现有的自监督学习综述大都专注于图像或时序信号领域，针对心电领域的自监督学习综述相对缺乏。为了填补这一空白，全面回顾了用于心电领域的先进的自监督学习方法。首先，从对比式和预测式两种学习范式出发对心电自监督学习方法进行了系统的总结与分类，阐述了不同类别方法的基本原理，细致分析了各个方法的特点，指出了各个方法的优势以及局限性。然后，归纳汇总了心电自监督学习中常用的数据集以及应用场景，总结了常用于心电领域的数据增强方法，为后续研究提供了系统性的总结参考。最后，深入讨论了当前自监督学习在心电领域中的挑战，并对未来心电自监督学习的发展方向进行了展望，为后续心电领域的自监督学习研究提供了指导。

关键词: 心电（ECG）, 特征表示, 深度学习, 自监督学习