Will there be fever post open heart surgery of aiotic valve replacement and bye pass surgery, if so, what should be done.?

Only transiently: If you have undergone aortic valve replacement and are running a fever this could signal potentially life-threatening complications and you should be seen both by the cardiovascular surgeon who did the procedure and by an infectious diseases expert.

Yes: Often observed cultures are useful if temperature is above 101.

Maybe: It is not uncommon to have an elevated temp following major surgery. There are several reasons why. You will be encourage to take deep breaths and use a sucking device called an incentive spirometer to keep your lung inflated. Getting out of bed and walking and increasing activity is important too. And occasionally it is caused by infection. That's why it's important to discuss with your surgeon.