The purpose of this study is to assess a dose titration scheme, of a new drug (BAY58-2667) given intravenously, to evaluate if this is safe and can help to improve the well-being, symptoms (e.g. breathing) and outcome of decompensated heart failure. Patients living with chronic heart failure have a risk of increased number of hospitalisations because of worsening of their condition (decompensated heart failure). The current treatment of acute heart failure consists of oxygen and medical treatment with vasodilators and positive inotropic agents (drugs, which should strengthen the pump function of the heart) which have their limitations. Therefore there is a need for new drugs in treatment of acute heat failure.