This study is for patients who are currently hospitalized with heart failure, a condition where the heart muscle is weakened and cannot pump blood effectively, and have low blood pressure. This study involves an investigational, not yet approved by the US Food and Drug Administration (FDA) intravenous (given into a vein) medication that is being studied to see if it can help increase blood pressure. The study involves a screening visit, randomization which is where either the study medication or placebo is assigned randomly, medication or placebo infusion for 24 hours, visits at day 2,3 and 4 and then a final visit at day 30.

This study is being done to find out if we can better monitor subjects with heart failure with the use of a wearable device (called SimpleSense garment) that can monitor multiple factors of heart failure that affect the body such as heart rate, activity, heart rhythm, and respiratory rate. Participants will wear the SimpleSense garment for 90 days for at least 12 hours daily. Participation in the study will include two research clinic visits and 2 phone calls over 4 months. Participants will be compensated for time and travel.

Risks of this study include loss of confidentiality, blood draw and skin irritation from wearing the garment.

The purpose of this registry is to observe outcomes of heart transplant recipients who are managed with HeartCare. This is done by collecting information about the participant's heart transplant such as test results, biopsy results, and outcomes, storing that information in a database, and using that information for research. HeartCare is a combination of two tests from one blood draw. One test, AlloMap®, is a well-established test for heart transplant recipients. The other test, AlloSure-Heart, is a new test that directly measures injury of the transplanted heart. HeartCare provides the results of both tests for a noninvasive assessment at time of testing. The registry will be active for up to 5 years after enrollment.