Use of brain natriuretic Peptide and bioimpedance to guide therapy in heart failure patients.

The key management goals for the stabilization of patients admitted for acutely decompensated heart failure (ADHF) include relief of congestion and restoration of hemodynamic stability. Nevertheless, in spite of clinical improvement, many patients are discharged with hemodynamic congestion. In response to volume expansion, the heart secretes the brain natriuretic peptide (BNP) with a biological action that counter-regulates the activation of the renin-angiotensin-aldosterone system. Since BNP is released by increased volume load and wall stretch, and declines after treatment with drugs of proven efficacy, on the basis of an improvement in filling pressures the level of BNP has been proposed as a 'measure' of congestion. The BNP level of a patient who is admitted with ADHF comprises two components: a baseline, euvolemic 'dry' BNP level and a level induced by volume or pressure overload ('wet' BNP level). So, the prognostic value of BNP during hospitalization depends on the time of measurement: from the lowest on admission when congestion is present (wet BNP) to the highest on clinical and instrumental stability (dry BNP), following the achievement of normohydration, as determined by fluid volume measurement. Euvolemia can be set as the primary goal of treatment for ADHF with dry BNP concentration as a target for discharge other than improvement of symptoms, because high BNP levels predict rehospitalization and death. Discharge criteria utilizing both BNP and hydration status measurement which account for the heterogeneity of the patient population and incorporate different strategies of care should be developed. This could in the next future offer an aid in monitoring heart failure patients or actively guiding optimal titration of therapy.