A 70 year old male presents with chest pain and is found to have an anterior wall myocardial infarction. Appropriate therapy is initiated, however he becomes profoundly hypotensive. His Swan-Ganz catheterization pressures are below (pressures in mmHg):
Right atrium - 20
Right ventricle – 44/19
Pulmonary artery – 46/24
Pulmonary capillary wedge pressure – 20
Cardiac index – 1.9 L/min/BSA2 (normal 2.4-4.4 L/min/BSA2)
Which of the following medications will siginficantly improve his cardiac index (cardiac output)?