Cardiac bypass surgery necessitates incision of the pericardium, which exposes the heart and facilitates surgical maneuvers. Cardiac bypass surgery is commonly used clinically to treat inadequate blood supply due to narrowing of one or more coronary arteries. Cardiac bypass surgery improves the blood supply to the heart muscle, relieves myocardial ischemia, and relieves angina. The pericardium covers the surface of the heart and has a protective effect on the heart. Therefore, during heart bypass surgery the pericardium is cut to expose the heart directly. It is only after the pericardium is cut that the exposed coronary vessels can be isolated, and then a channel can be created proximal and distal to the narrowed area of the coronary vessels to normalize the blood supply. Prior to surgery, it is recommended that you fully communicate with your doctor about the specifics.