Cardiology is a specialty of medicine that is mainly concerned with disorders of the heart and circulatory system. It also focuses on the diagnosis and treatment of congenital heart defects, heart failure, valvular heart disease, and electrophysiology. A doctor who has specialized in this field of medicine is called cardiologist, a specialty of internal medicine. Child cardiologists are known as Pediatric Cardiologists. Physicians who perform cardiac surgery are known as cardiothoracic surgeons or cardiac surgeons, a specialty of general surgery.