Cardiology is a branch of internal medicine that deals with the disorders of the heart and the circulatory system. The field encompasses medical diagnosis, electrophysiology, cardiovascular medicine, and treatment and management of heart conditions such as: heart failure, cardiac arrhythmia, coronary artery disease, congenital heart defects, valvular heart disease, aortic aneurysms, rheumatic heart disease, hypertensive heart disease, cardiomyopathy, and thromboembolic disease etc. The subspecialties of the cardiology include interventional cardiology, echocardiography, cardiac electrophysiology, and nuclear cardiology. However, it should be remembered that cardiology is a medical and not surgical discipline. Physicians who specialize in cardiology are called cardiologists; they perform basic studies on heart function and supervise all aspects of therapy, including drug administration. The specialty of cardiology integrates physician, surgical, and radiological skills, all under one specialty.