What are congenital heart defects?

By Cristiano Antonino On Nov 18, 2022

The term ‘congenital’ means ‘existing at birth’. Congenital defects include all those alterations in the structure or function of one or more organs that occurred before birth, at conception or during embryo-fetal life

A congenital heart defect is present when the heart or blood vessels near the heart have not developed normally before birth (the heart forms in the first four to ten weeks of pregnancy).

Congenital heart defects are among the most frequent malformations: their incidence (number of new cases in a population), calculated as the number of children with heart disease out of the total number of live births, is approximately eight cases per thousand live births (in Italy, approximately 4,000 babies are born each year with a form of congenital heart disease).

The incidence of congenital heart defects has remained essentially stable over the past 50 years, in the various case series collected

However, studies have shown that parents (and in particular mothers) affected by a congenital heart defect have a higher incidence of children who are also affected; it may be reasonable to predict a slow increase in the incidence of congenital heart anomalies over the years, thanks to newer medical and surgical therapies that can heal children with these defects, giving them the chance to grow up and have children.

Cardiac malformations can be of various types: they range from abnormalities affecting a single part of the heart (e.g. a valve) to very complex abnormalities characterised by major alterations in the cardiac architecture.

Obviously, the severity of the heart disease and its repercussions on health also vary: there are forms that do not cause an health problems and allow a normal life, and forms that are incompatible with life.

Thus, having a congenital heart disease does not necessarily mean having a serious illness; however, there are some congenital heart defects that are so complex that they can lead to the death of an infant within a few days, unless immediate medical or surgical intervention is carried out.

Classification of congenital heart defects

Congenital heart defects can be classified into severe, moderate and mild

Severe congenital forms are defined as those congenital forms that are responsible at birth or within the first few months of life for a serious condition; these, in turn, can be subdivided into ‘cyanotic’ forms (= giving a bluish discolouration to the skin) and ‘noncyanotic’ forms. The incidence of severe forms is stable over the years and is, in the various case series, around 2.5-3 per thousand live births.
Moderate forms are defined as those that require non-intensive cardiological treatment at birth or are only diagnosed after the first few months of life. The incidence of this form is also about 3 per thousand live births.
Mild forms are defined as those present in individuals without symptoms, which often resolve spontaneously; they are the largest group; the estimated frequency of these lesions varies depending on whether the diagnosis is made in neonatal or paediatric age, or in adulthood (this is the most frequent case).

What are the most frequent congenital heart defects?

Within congenital heart defects, some forms are definitely more frequent than others.

Among the most frequent forms are the interventricular defect (which accounts for 28-32% of all congenital heart diseases), the interatrial defect (approx. 9%), pervious Botallo’s duct and aortic coarctation (approx. 8%), Tetralogy of Fallot (approx. 6%), complete transposition of the great arteries (approx. 5%).

The interventricular defect, which depending on its size can be classified into severe, moderate or mild forms, is by far the most frequent heart defect (it affects around 30% of all patients with congenital heart disease): fortunately, however, 85% of cases are mild forms that tend to close spontaneously in the first year of life.

The interatrial defect and the foramen ovale pervio are fairly frequent and are among the mild forms of congenital heart defects; they can be present from birth, but are often only noticed in adulthood

Interatrial defect (800-1000 new cases each year) is a heart defect characterised by the presence of a hole in the muscular wall that normally separates the two atria (which are the two upper cavities of the heart), through which there is a passage of blood, usually from the left to the right atrium.

This abnormality does not usually cause discomfort in children, but in adulthood it can cause symptoms (fatigue, shortness of breath, alterations in the normal rhythm of the heart).

The foramen ovale pervio is present in about a quarter of the Italian population (more or less 15 million people), but it is only a health risk in certain cases, when the blood passing from the right to the left atrium carries small blood clots, which come from the legs and can block the flow of blood in small arteries.

How can a congenital heart defect be detected?

The diagnosis of congenital heart disease is mainly based on clinical, radiographic and echocardiographic examinations In recent years, the increasing popularity of echocardiography, a non-invasive diagnostic method based on ultrasound, has greatly increased the chances of diagnosing congenital heart defects early (even during intrauterine life); on the other hand, since prenatal diagnosis is now possible, recourse to pregnancy termination for more complex heart diseases has increased, thus significantly reducing their incidence in live births.

Severe forms (both cyanotic and noncyanotic) are diagnosed at birth or, thanks to ultrasound methods, even during foetal life.

Moderate forms are usually diagnosed by the cardiologist after the first few months of life.

Mild forms, which may remain asymptomatic until adulthood, are usually diagnosed after the onset of symptoms: in these cases too, echocardiographic examination is the key test; sometimes the defect may be revealed quite incidentally (e.g. by an echocardiogram performed for other reasons).

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