Amrinone: A positive inotropic cardiotonic (CARDIOTONIC AGENTS) with vasodilator properties, phosphodiesterase 3 inhibitory activity, and the ability to stimulate calcium ion influx into the cardiac cell.Aminopyridines: Pyridines substituted in any position with an amino group. May be hydrogenated, but must retain at least one double bond.Cardiotonic Agents: Agents that have a strengthening effect on the heart or that can increase cardiac output. They may be CARDIAC GLYCOSIDES; SYMPATHOMIMETICS; or other drugs. They are used after MYOCARDIAL INFARCT; CARDIAC SURGICAL PROCEDURES; in SHOCK; or in congestive heart failure (HEART FAILURE).Milrinone: A positive inotropic cardiotonic agent with vasodilator properties. It inhibits cAMP phosphodiesterase type 3 activity in myocardium and vascular smooth muscle. Milrinone is a derivative of amrinone and has 20-30 times the inotropic potency of amrinone.Rewarming: Application of heat to correct hypothermia, accidental or induced.Phosphodiesterase Inhibitors: Compounds which inhibit or antagonize the biosynthesis or actions of phosphodiesterases.