Device Sensing

Abstract

Device therapy for the management of cardiac arrhythmias has evolved from asynchronous pacing in postsurgical heart block and Stokes-Adams attacks1 to the use of implantable cardioverter defibrillator (ICDs)2 and cardiac resynchronization therapy for the prevention of sudden cardiac death and the treatment of heart failure.3 Algorithms have been developed to optimize pacemaker response during arrhythmias and minimize pacing if indicated by cardiac physiology. Over the last several decades, technological advances and a better understanding of cardiac physiology allowed the development and miniaturization of devices that not only monitor and react to the electric signals from intracardiac electrograms but also use physiological signals to optimize pacing function and monitor disease state. It has become a reality to store this information in modern devices and transmit it to a clinical center, even on a daily basis if needed, by use of a transtelephonic or Internet-based route. As current and emerging indications for device therapy have targeted increasingly larger patient populations,4 we are now able to use implantable devices to monitor patients at risk of adverse cardiac events. Emerging technologies aim to provide continuous hemodynamic information to aid the management of chronic heart failure. Technologies under clinical investigation include impedance-based monitoring of fluid status, hemodynamic assessment based on pulmonary artery pressure and its derivatives, or direct left atrial pressure monitoring. A promising possibility is that the information obtained from monitors may be used to predict and avoid adverse clinical outcomes earlier than changes in clinical parameters would otherwise indicate, which would allow physicians an opportunity for earlier intervention. In the present review, we will discuss currently used sensors in cardiac devices and draw attention to some of the future applications of device sensors.