OPEN HEART SURGERY- It depends on various factors and type of heart surgery done. I fell in 13 year old oHS fat can be taken in moderate levels. Many people do not understand what is open-heart surgery and generalise the term open-heart surgery to all heart surgery. Any surgical procedure opening the heart and exposing one or more of its chambers, most often to repair valve disease or correct congenital heart malformations is termed as OPEN HEART SURGERY. Invention of the heart-lung machine (see artificial heart), which allows the heart to be stopped during surgery, made it possible. Most common heart surgery done is CABG (Cardiac Artillery Bypass Grafting. For a 13 year old it will not be CABG and most probably it will be valve replacement surgery only. For patients who had this surgery there is no hard and strict restictions on consuming Fat. Fat is very much concerned for the CABG patients as their arteries get blocked with Cholestral derived out of fat and they get heart attack. Bypass grafting is done to avoid flow of blood through the blocked portion and make easy flow of blood by a alternate route. For patients who had CABG the doctor will probably recommend that a low fat, no added salt diet after discharge. This may reduce your risk of a heart attack in the future and of your risk for requiring angioplasty or surgery again. In general also it is better to reduce intake or avoid consuming fat.You have to try to control your weight and eat less saturated fat and cholesterol.