Heart monitoring systems—A review

• We classified portable heart monitoring systems in two manners, on-site and off-site.
• Off-site heart monitoring systems have been introduced in five modules.
• A detailed review of recent advancements in each module has been provided.
• Phonocardiography, electrocardiography, photoplethysmography and seismocardiography are discussed for long term heart monitoring.
• Smart phones based heart monitoring system and their challenges have been discussed.

To diagnose health status of the heart, heart monitoring systems use heart signals produced during each cardiac cycle. Many types of signals are acquired to analyze heart functionality and hence several heart monitoring systems such as phonocardiography, electrocardiography, photoplethysmography and seismocardiography are used in practice. Recently, focus on the at-home monitoring of the heart is increasing for long term monitoring, which minimizes risks associated with the patients diagnosed with cardiovascular diseases. It leads to increasing research interest in portable systems having features such as signal transmission capability, unobtrusiveness, and low power consumption. In this paper we intend to provide a detailed review of recent advancements of such heart monitoring systems. We introduce the heart monitoring system in five modules: (1) body sensors, (2) signal conditioning, (3) analog to digital converter (ADC) and compression, (4) wireless transmission, and (5) analysis and classification. In each module, we provide a brief introduction about the function of the module, recent developments, and their limitation and challenges.