Normal Heart Physiology
The left ventricle is the main pumping chamber providing sufficient contractile force to expel blood round the body through the arteries. The right ventricle is the pumping chamber which delivers blood to the lungs through the pulmonary artery and its tributaries, and is called the pulmonary circulation.
Normal Heart Anatomy
The heart is a series of muscular pumps. The aorta is the main artery of the body – it carries blood away from the heart and delivers it to the other organs. Blood then passes through capillary beds in the organs where exchange of oxygen, carbon dioxide and nutrients like glucose, takes place. Blood returns from the organs to the right side of the heart through the veins.
Coronary Heart Disease
Angina is caused by a blockage in one or more of the coronary arteries. The blockage is caused by atherosclerosis (furring of the arteries), which causes the artery to narrow off. Once the artery has a narrowing inside, it prevents the blood from flowing normally and therefore prevents the heart muscle getting the blood (and Oxygen) it needs. This results in a cramping like sensation or heaviness in the chest. Left untreated atherosclerosis can cause heart attacks.
Heart Valve Disorders
There are four valves in the heart; two protect the main outflow tracts – the aortic and pulmonary and two lie between the atria and the ventricles – the mitral and tricuspid. These valves are essential for the normal functioning of the heart as they only allow blood to flow in one direction only under normal circumstances. However they may be narrowed and restricted in their opening which is called stenosis, or leak and become incompetent. If the valves do not work correctly then this causes either a pressure or a volume overload on the ventricles.
Heart Failure
When the left ventricular muscle is damaged and not able to pump efficiently, then the systemic blood pressure and cardiac out put fall. This is compensated for by an increase in the heart rate in order to try to increase the cardiac output back to normal
Rhythm Disorders
Sometimes, if the conduction pathway is damaged or becomes blocked, or if an extra pathway exists, the heart’s rhythm changes. The heart may beat too quickly (tachycardia), too slowly (bradycardia) or irregularly which may affect the heart’s ability to pump blood around the body. These abnormal heartbeats are known as arrhythmias. Arrhythmias can occur in the upper chambers of the heart, the atria, or in the lower chambers of the heart, the ventricles.