Holter monitoring of patients with CHF shows 90% have premature ventricular contractions and non-sustained ventricular tachycardia (rapid beating) show up in 60% of patients (according to Stevenson WG, et al 1994) and atrial fibrillation in approximately 20% of patients (according to Smith TW, et al 1997). The occurrence of arrhythmias may be associated with a decrease in ventricular performance, which may worsen the symptoms of acutely decompensated CHF and complicate patient management. The ventricle is the heart's pumping chamber that pumps the oxygen-poor blood returning from the body into the arteries of the lungs, where the blood picks up oxygen. In atrial fibrillation the heart's two small upper chambers (the atria) quiver instead of beating effectively. Therefore, it is imperative that new therapies developed for the treatment of decompensated CHF not be associated with the development or an increase of arrhythmias. Natrecor® has been studied as an IV treatment for decompensated CHF in over 500 patients. As interstitial fluid (in the lung tissues) accumulates in advanced CHF cases, the pulmonary capillary wedge pressure (PCWP) increases. However administration of a continuous IV infusion of Natrecor® resulted in dose-related decreases in PCWP, right atrial pressure, and systemic vascular resistance, and an increase in cardiac index which is a measurement of the volume of blood pumped by the heart, (according to Marcus LS, Hart D, Packer M, et al 1996; Abraham WT at al 1998; and Mills RM et al 1999 ). Beneficial improved blood flow throughout the body associated with a decrease in the systolic blood pressure - heart rate index (the double product), suggests that Natrecor® improves cardiac performance while not increasing estimated myocardial oxygen consumption.