Located in the middle of the chest behind the breastbone, between the lungs, the heart rests in a moistened chamber called the pericardial cavity which is surrounded by the ribcage. The diaphragm, a tough layer of muscle, lies below. As a result, the heart is well protected. To monitor the heart , scientists can use x-ray or scanning technology to get a picture. To really explore the heart, scientists have to perform surgery.
Heart surgery is very risky because the heart's pumping action is so critical for survival.
If the heart stops pumping, the body cannot survive. Before beginning heart surgery, doctors connect the patient to a machine that pumps the blood for the heart. Only then is it safe for the doctor to stop the heart in order to operate.