Implantable Sensors for Cardiac Function Monitoring

As heart diseases represent the leading causes of death in the world and the rapidly aging population tends to increase the prevalence of these pathologies, implantable sensors for the continuous monitoring of cardiac function are receiving considerable interest and investment. This article provides an overview of important aspects and challenges dealing with implantable sensor systems for cardiac function monitoring, and it discusses past and recent developments in this area. Part one is a general introduction on design principles for the development of implantable systems, including considerations about the human body's interaction with the implanted device; the appropriate choice of materials, coatings, and packaging techniques (biocompatibility/biostability); and concerns about miniaturization and low-power consumption requirements. Subsequent sections discuss various applications of implantable sensors for cardiac function monitoring, starting from the initial experience of rate-responsive sensors for cardiac pacing up to focus on sensors, most intensely investigated in the last decade, for monitoring cardiac function alterations secondary to heart failure. A final section is provided about future directions and emerging technologies on implantable sensors for cardiovascular applications. The major challenge for the fulfillment of a successful implantable sensor for cardiac function monitoring deals with demonstrating its clinical effectiveness, along with ensuring its long-term stability and reliability. To date, many sensors have been investigated, but few of them truly meet these goals and demonstrate their appropriate clinical roles.