In patients admitted with acute myocardial infarction, there is a total occlusion of a coronary artery. Even after emergency catheterization and angioplasty, in some patients, the resumed blood flow is suboptimal and impacts on heart function. The study is aimed at examining whether nitroprusside, an anti-hypertension medication, given directly into the coronary artery, can improve the blood flow after the removal of the obstruction that caused the infarction.