The Normal and Congenitally Abnormal Heart

The Normal Heart

The heart is a muscle pump divided into 2 sides the right and left. Each side has two chambers, one which collects blood (atrium) at low pressure and one which pumps blood out of the heart (ventricle) and operates at high pressure.

Each atrium receives blood from veins (right atrium - superior and inferior vena cava; left atrium - pulmonary veins from the lungs).

Each side of the heart has two valves one between each atrium and ventricle (right side - tricuspid valve; left side - mitral valve), and one at the exit of each ventricle (right side - pulmonary valve; left side - aortic valve) where the blood is pumped out to the arteries (right side - pulmonary artery; left side - aorta). The right side of the heart receives blue blood (low oxygen) from the body and pumps it to the lungs to collect oxygen. The blood returns to the left side of the heart via the pulmonary veins and is pumped by the left ventricle into the aorta so blood rich with oxygen can reach the body.

The Congenitally Abnormal Heart

In the Congenitally Abnormal Heart one or more parts of the heart structure differs from normal. Congenital simply means present from the time of birth. There are many different abnormalities that may affect the valves, heart chambers, arteries, or any combination of these. An abnormality is not necessarily serious each baby or child is different and there are variations of severity even within abnormalities which have the same name. Some abnormalities never need medical intervention.

A common distinction between congenital abnormalities are those in which the oxygen level reaching the body is normal (acyanotic) and, more rarely, those where the blue and pink blood mix, lowering the level of oxygen reaching the body (cyanotic). When a baby has cyanotic heart disease, although the level of oxygen may be lower than normal, the baby is well adapted to this because oxygen levels are low while the baby is being carried during pregnancy. As long as the oxygen level is in a "safe" zone, the baby will remain well. Abnormalities described in documents available on the Heart Centre for Children web site include:

•  Septal defects
•  Valve abnormalities
•  Tetralogy of Fallot
•  Transposition of the Great Arteries
•  Single ventricles and the Fontan circulation

Disclaimer: This information is intended as a general guide only and not to provide specific information for individual patient care. Any questions about your own situation should be directed to your medical practitioner, or cardiac specialist, or you can contact us and ask to speak to a Clinical Nurse Consultant.