Update on device technologies for monitoring heart failure

Congestive heart failure (CHF) affects more than 5 million people in the United States and is one of the most common reasons for recurrent hospitalizations. Since the majority of admissions related to CHF are secondary to progressively worsening congestion, many clinicians are quick to initiate aggressive diuresis once early signs of impending heart failure develop. These signs are based in large measure on patient-reported symptoms. Unfortunately, recent trials have shown that traditional ambulatory monitoring of heart failure using patient symptoms or body weight do not reduce episodes of decompensated heart failure requiring hospitalization. This has led to great interest in developing monitoring systems that can detect impending episodes of CHF even prior to the development of symptoms. Some of the these systems utilize existing implantable cardioverter defibrillators and cardiac resynchronization therapy devices to monitor electrophysiologic parameters including the presence of ventricular arrhythmias, heart rate variability and even transthoracic impedances. Other more recent developments have focused on more invasive hemodynamic monitoring systems that can measure pressures in the right ventricle, pulmonary arteries and the left atrium. The data on the utility of such systems is limited but encouraging. While none of these systems are currently FDA approved, they have been applied in a number of clinical trials. This paper highlights the currently available monitoring systems for heart failure and reviews the evidence supporting its use.