An Exploratory Study of Nesiritide in Participants With Acute Heart Failure

The purpose of this exploratory study is to assess the efficacy and safety of nesiritide in participants with acute (a quick and severe form of illness in its early stage) heart failure (when the heart inadequately pumps blood through the body) including acute exacerbation of chronic (lasting a long time) heart failure, administered intravenous (into a vein) bolus (a large amount) followed by intravenous infusion (a fluid or a medicine delivered into a vein by way of a needle).

This is an open-label (a medical research study in which participants and researchers are told which treatments the participants are receiving, "unblinded"), multi-center (when more than 1 hospital or medical school team work on a medical research study), randomized (study medication assigned by chance), stepwise, bolus plus intravenous infusion, fixed-flexible (arbitrary dose titration \[slow increase in drug dosage, guided by participant's responses\]) study. The study consists of 3 periods: Observation period (from the time of obtaining consent to the start of study treatment), Treatment period, and Follow-up period (from 24 hours after the initiation of study treatment \[discontinuation\] to 30 days after the initiation of study treatment). The participants will be randomly assigned to 1 of the following 3 treatment groups: 2+0.005 group, 1+0.01 group and 2+0.01 group. The treatment period consists of treatment with bolus injection (over 1 minute) followed by intravenous infusion (over 24 hours: Period 1 \[fixed-dose period\] of 3 hours and Period 2 \[flexible-dose period\] of 21 hours).The study will be conducted stepwise and hence, initially participants will be randomly assigned to 1 of the following 2 groups: 1+0.01 group and 2+0.005 group. Participants will receive nesiritide at an initial dose of 0.005 or 0.01 microgram per kilogram per minute (mcg/kg/min), and the dose escalation of 0.005 mcg/kg/min per dose will be conducted every 3 hours up to maximum of 0.03 mcg/kg/min in Period 2. Safety data of at least 5 participants will be assessed for each group, and after confirming the safety of 2 groups, the participants will be assigned to third group of nesiritide 2 microgram per kilogram (mcg/kg) +0.01 mcg/kg/min. Then participants will be followed up to a maximum of 30 days after the initiation of study treatment, in follow-up period. Participants will primarily be evaluated for the effect of nesiritide on hemodynamic parameters such as pulmonary capillary wedge pressure (PCWP), or if it is unmeasurable then it will be complemented with pulmonary arterial diastolic pressure (PADP). Participants' safety will also be monitored throughout the study.

Eligibility Criteria:
Inclusion Criteria:

* Participants with acute heart failure (including acute exacerbation of chronic heart failure) requiring hospitalization whose placement of right-heart catheter (flexible, tube-like tool used to take fluids out or put fluids into the body) is judged to be possible and useful for treatment
* Participants with findings of pulmonary (having to do with the lungs) congestion on a chest X-ray (an image of a site produced on photographic film by X-rays passing through the site) film taken within 12 hours before starting the treatment
* Participants with 2 systolic blood pressure (SBP: refers to blood pressure \[pressure of the blood on the arteries and other blood vessel\] when the heart beats while pumping blood) values greater than or equal to 100 millimeters of mercury (mmHg) measured at an interval of at least 15 minutes in the hemodynamic (related to blood flow) assessment in observation period
* In a hemodynamic assessment in observation period, participants with 2 pulmonary capillary wedge pressure (PCWP \[if it is not available, pulmonary arterial diastolic pressure {PADP}\]) values greater than or equal to 18 mmHg measured at an interval of at least 15 minutes and the second measurement value is within positive 20 percent (%) and negative 20% compared with the first 1

Exclusion Criteria:

* Participants with severe (very serious, life threatening) hepatic (to do with liver) impairment or renal (to do with kidney) impairment, cancer (abnormal tissue that grows and spreads in the body until it kills), or malignant (cancerous) tumor (a mass in a specific area)
* Participants who are or may be pregnant or breast-feeding
* Participants receiving non-invasive (puncture, opening or cutting of the skin) positive pressure ventilation (NIPPV) or scheduled to receive this during the study period
* Participants who received treatment with another investigational product within 4 weeks before the initiation of investigational treatment or who were enrolled in a clinical study of nesiritide in the past
* Participants who received prohibited concomitant medications within 3 hours before the initiation of investigational treatment or those who are receiving such a medication