Study of Electrical Bioimpedance in Heart Failure.

Heart failure (HF) is a clinical syndrome presenting currently a high prevalence, morbidity and mortality. The lack of sensitivity of symptoms and signs used to make the diagnosis of the exacerbation of HF, and the knowledge in recent years about the relevance to detect congestion before consulting a specialist or go to the emergency department, support the need of more aggressive management of these patients. Bioimpedance monitoring devices for bioimpedance can provide useful data for the detection of congestion onset and help the decision-making in treatment. Because patients with heart failure suffer alterations in body composition, mainly due to the amount of extracellular water, the bioimpedance can objectify these variations. In heart failure, bioimpedance has been tested in two studies with small samples of patients estimating total body water. In other studies , the monitoring of intrathoracic impedance has been performed by measurement systems implanted in cardiac defibrillators or in cardiac resynchronization devices. They have proven to be useful for early detection of decompensation in these patients and to detect changes in impedance before the patient begins the clinical manifestations. Furthermore, it has been correlated the detection of decompensation by these devices with significant increases in NT- proBNP (diagnostic and prognostic marker for HF). The purpose of our study is to observe these changes in impedance from the patient's skin surface and non-invasively.