The formation of the heart is a very complex process - errors can occur at every step in its development. They lead to congenital disorders that, due to an incidence of 1 in 1000 newborns, belong to the most frequent birth defects. Chromosomal aberrations are also very frequently associated with heart abnormalities. In the future, it will probably be possible to trace even more congenital malformations back to genetic predispositions when the processes that lead to heart formation are better understood at the molecular level.
In the clinic 4 very frequent heart abnormalities dominate. They make up more than half of the ones that are encountered. They are:
- VSD = ventricular septal defect (28%)
- ASD = atrial septal defect (11%)
- Pulmonary stenosis (9%)
- PDA= persisting ductus arteriosus (9%)
One can also subdivide congenital heart abnormalities according to location and hemodynamic effects. In case of an incomplete separation of the lungs and somatic circulation systems a shunt is formed. With each cardiac contraction the blood goes over from one circulation system to the other according to the different blood pressures in the two systems.
Cardiac abnormalities can thus be subdivided into the following three groupings:
- Anomalies without shunt
- Anomalies with left-right shunt (normally without cyanosis)
- Anomalies with right-left shunt (with cyanosis --> mixed blood)
Besides auscultation (with the stethoscope) echocardiography is the most frequently applied diagnostic method for clinical examinations.
Cardiac catheter examinations are indicated in complex cardiac abnormalities and before operations.