Cardiology is a medical specialty and a branch of internal medicine concerned with disorders of the heart. It deals with the diagnosis and treatment of such conditions as congenital heart defects, coronary artery disease, electrophysiology, heart failure and valvular heart disease. Subspecialties of the cardiology field include cardiac electrophysiology, echocardiography, interventional cardiology and nuclear cardiology.

The basic functioning of the cardiovascular system includes the way the heart processes oxygen and nutrients in the blood, which is called coronary circulation. The circulation system consists of coronary arteries and coronary veins.

There are a range of disorders of the cardiovascular system that are treated and studied under the field of cardiology. Among them are acute coronary syndrome, which encompasses the broad range of myocardial infarction symptoms. Angina pectoris, coronary heart disease and restenosis are other common disorders. Broader categories of disorders in the field of cardiology include cardiac arrest; disorders of the myocardium, or the muscle of the heart, which include varieties of cardiomyopathy; disorders of the pericardium, or the outer lining of the heart, which include types of pericarditis; disorders of the heart valves, including the aortic valve, the mitral valve, the pulmonary valve and the tricuspid valve; congenital heart defects, which range from atrial septal defect to ventricular septal defect; diseases of the blood vessels, or vascular diseases, which includes aneurysm,varicose veins, vasculitis and diseases of other blood vessels.

Several devices are used in cardiology, including various types of balloons and defibrillators, a pacemaker, and a stethoscope. Artificial hearts also are used and studied in the field of cardiology.