Ok, so what's heart failure? 

Heart failure is when the heart is not meeting the cardiac output it's supposed to pump out. What could cause the the decreased cardiac output? 2 things: decreased Heart Rate or decreased Stroke Volume. Remember that Starling equation? CO = HR x SV? That's the one. 

Acute heart failure: So, in acute situation, when the the heart suddenly acutely slows down. It could cause cariogenic shock. So, what do you do?  You would want some meds that mimic the normal physiology of cardiac output to make the heart work: therefore you'd want some beta adrenergic drugs or drugs that predominantly work on the beta adrenergic receptors. What are these 2 drugs? Dobutamine & Milrinone.

Well, to say that drugs that mimic the heart's adaptation mechanisms is partially correct and wrong too. Depending on how bad the oxygenation is, you may want to add Nitrates. Now remember, in adaptation mechanisms, the heart increases preload by retaining sodium and water. Ordinarily, this would do it. However, if too much sodium & water, you may have pulmonary HTN, therefore you may have diffulty breathing. Thus, you'll need to vasodilate => nitrates (only when oxygenation is not working).

~Wonder Me