Assessing the risk of congenital heart disease can prove problematic. Wendy Hickman looks at the implications for protection cover
A congenital abnormality of the heart's structure, which is present at birth, originates from the stage in early pregnancy when the heart is forming.
It can affect any of the different parts or functions of the heart. These can range from mild disorders such as 'holes' between chambers of the heart, to severe disorders such as complete absence of one or more chambers or valves. In fact, some defects can be so minor that they remain undetected for many years after birth.
Defects may be due to abnormal foetal development of the heart during pregnancy and therefore the cause is usually unknown. However some defects of the heart can be associated with genetic disorders, which are more likely to occur in siblings or offspring of people that have heart defects, than in unaffected families.
Abnormal development
Other potential risk factors include taking certain medications during pregnancy, drinking alcohol, and viruses affecting the mother during pregnancy. Certain chronic illnesses such as diabetes also carry a higher risk factor to the unborn foetus but can be greatly reduced or eliminated if the condition is monitored closely during the pregnancy.
One thing that all congenital heart defects have in common is that it is unknown exactly why it develops and that it involves abnormal or incomplete development of the heart.
Some of the most common congenital defects include:
• Patent ductus arteriosus - prior to birth the ductus arteriosus is used to join the arch of the aorta to the pulmonary artery. This passageway is used to allow much of the foetus' blood to flow through from the pulmonary artery to the aorta, instead of through the lungs, because at this stage the lungs are not yet in use. The passageway should then close soon after birth to enable the blood to take the normal route from the heart to the lungs and back. If this is not the case and the passageway remains open, then medication can be taken to help close the passageway or surgery can be performed.
• Atrial septal defect - the atrial septum is the wall that separates the left and right atria, which are the upper chambers of the heart. A hole or opening in this septum means that blood is unable to flow through the heart as it should, therefore allowing too much blood to flow to the lungs. If a small hole is detected, this may close on its own and not require surgery, however larger holes may require surgery later in life.
• Fallot's tetralogy - a combination of four abnormalities consisting of a hole in the septum between the ventricles (ventricular septal defect); displacement of the aorta allowing blood to flow from the right ventricle to the aorta (aortic misplacement); a narrowing of the outflow passage from the right side of the heart (pulmonary stenosis); and a thickening of the wall of the right ventricle (right ventricular hypertrophy). As a result of the defects, some blood is stopped from getting to the lungs causing cyanosis or blueness. This may be apparent soon after birth, infancy, or later in childhood, along with other symptoms such as rapid breathing, and even loss of consciousness. Surgery is normally required to repair the defects.
• Coarctation of the aorta - is the narrowing of the aorta, which means blood can't flow normally from the heart via the aorta artery to the rest of the body. The narrowing may occur at any site although the stenosis is usually situated near the ductus arteriosus. While the diagnosis may not be made until later in life, it can be treated with surgery or dilation.
• Transposition of great vessels - is where the pulmonary artery and the aorta are switched, therefore the body is unable to get the oxygenated blood it needs to survive. The oxygenated blood is pumped back to the lungs rather than being distributed to the body and the deoxygenated blood is pumped back to the body instead of being sent back to the lungs.
Other less common congenital heart defects include:
• Hypoplastic left heart syndrome, in which the left side of the heart is underdeveloped.
• Tricuspid atresia, in which there is no tricuspid valve so blood cannot flow, as it should from the right atrium to the right ventricle.
• Pulmonary atresia, in which there is no pulmonary valve, so blood cannot flow, as it should from the right ventricle and on to the lungs.
• Atrioventricular canal defect, in which a large hole exists in the centre of the heart.
• Sub-aortic stenosis, in which there is constriction just below the aortic valve.
• Ebstein's anomaly, which is a displacement of the tricuspid valve.
Wendy Hickman is life and disability underwriter at Scottish Equitable Protect
