what happens when your heart beats low at 37?

Have you already consulted your physician about this problem? If not do so as soon as possible. While you are most likely fine, it is always best to check.

It is unlikely that Warfarin is the cause of your pericardial effusion. It could be a late complication of surgery or it could have another cause altogether. Pericardial effusion can produce shortness of breath as can heart failure. I am not your doc, but could I send you a bill? I really would ...

It is up to you, but not necessary.

After bypass surgery risk of angina reduces and patient can live longer. You need to switch on to healthy lifestyle to make your heart stronger. There is no option for healthy diet and regular exercise.