Introduction

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Basic Cardiology

Cardiology is a medical speciality dealing with the diagnosis and treatment of diseases and disorders of the heart. The heart is a complex organ that supplies the body with the blood and oxygen it needs to function properly. The heart can be thought of as a muscle that functions as a pump. It is divided into four chambers or cavities. The upper chambers, called atria, are receiving or collecting chambers for blood returning to the heart. They empty blood into the lower chambers, called ventricles, which are the pumping chambers of the heart.

The heart is also divided into a right and left side. The right atrium receives blood from the veins in your body and empties it into the right ventricle. The right ventricle pumps the blood to your lungs to pick up oxygen. The oxygen rich blood then enters the left atrium and finally the left ventricle that is the primary pumping chamber of the heart. The left ventricle pumps blood through the aorta, the main artery in the body, to all of the body organs and tissues. Four heart valves, located between the chambers, keep blood moving from chamber to chamber in the right direction. Every time the heart pumps it produces electrical activity that can be measured. The electrocardiograph (ECG) is an image from an instrument which, when placed in contact with the chest, will register graphically the comparative duration and intensity of the heart's movements. An electrocardiograph is used in the investigation of heart disease.

History
The heart has been regarded throughout recorded history as an important organ, but the structure and function of the cardiovascular system have been misunderstood for much of that time. The Greek physician Galen in the second century AD is credited with first recognising that the heart and vessels contained blood rather than air, but he erroneously thought that blood moved from one chamber of the heart to another by seeping through perforations in the muscular divisions, and that blood flowed to the periphery through the effects of a mysterious "attractive force".

Galen's views persisted for over 1,500 years until Dr. William Harvey, through careful experimentation and deductive reasoning established the modern view of the cardiovascular system, which has since been refined, but not significantly altered.

Cardiology first became a specialised field of study when Jean Baptiste de Sénac in 1749 published a summary of contemporary knowledge of the heart. This was followed 12 years later by Leopold Auenbrugger's discovery that the condition of the heart can be estimated by the sound returned from tapping on the chest (percussion). Listening to heart sounds became a major part of medical diagnosis after René Laënnec's invention of the stethoscope in 1816. Much of the development of cardiology during the 19th century consisted of improved diagnostic methods.

An important diagnostic advance was Willem Einthoven's invention in 1903 of the electrocardiograph, which measures the heart's electrical activity. By 1915 the basic methods of diagnosis of heart disease, including fluoroscopic studies of the beating heart, were in place. Various advances in diagnostic technology opened up the possibility of surgical correction of many heart problems. Cardiology itself remains a medical, not a surgical, speciality although cardiologists work closely with surgeons in cases of heart surgery. Cardiologists provide the continuing care of heart patients, performing basic studies of heart function and supervising all aspects of therapy, including the administration of drugs to modify heart functions.

Much of the development of cardiac medicine in the second half of the 20th century has been in the field of heart surgery. Major advances in this field have included the routine repair of coronary artery disease, one of the major causes of heart attacks; the first human heart transplant, performed by Christiaan Barnard of South Africa in 1967; and the development of a permanently functioning, surgically implanted artificial heart by a research team at the University of Utah, first used in 1982.

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