The primary objective of this study is to compare the effects on heart rate and ventricular arrhythmias of two doses of Natrecor® to dobutamine, during the first 24 hours of treatment of decompensated CHF. The primary outcome of the study is an evaluation of: (1) average heart rate, (2) average hourly premature ventricular beats, and (3) average hourly repetitive beats, all expressed as a change from baseline, as measured by Holter monitoring (a portable device that provides continuous monitoring of the electrical activity of the heart). Additional objectives include exploring the effects of Natrecor® and dobutamine on other Holter outcomes such as couplets, triplets, and ventricular tachycardia and the evaluation of ventricular ectopy (seven or more single premature ventricular beats per minute or any run of more than two ventricular ectopic beats) by the application of specific proarrhythmic criteria. Clinical symptoms are also measured.