hello, my father has under gone by pass surgery five months before.after that he has recover well.soon he has to change his work place to another city.he was a bit exhausted while shifting and being settled in new place.last week he had breathing problem and cough.he went to doctor and took x-ray . he was told that their is some water in lungs and his heart is 40% working.i want to know the reason for water in lungs and what is this 40% working of heart?