Heart abnormality with right-left shunt (cyanotic)
In cardiac abnormalities with right-left shunts oxygen-poor blood gets from the right half of the heart into the left side and thus into the systemic circulatory system. In most of the defects with right-left shunts the physiologic shunts present before birth remain functional because no reversal of pressure happens following birth.
Fallot's tetralogy, described in 1888, is met with in roughly 8% of all congenital cardiac abnormalities. It comprises the following defects:
- Pulmonary stenosis (PS)
- Ventricle septum defect (VSD)
- Overriding aorta
- Right ventricular hypertrophy
Pulmonary valve atresia
This cardiac abnormality is very rare and accounts for only 1-3%. In this affliction the pulmonary valve is atretic and there is no exit from the right ventricle. Thus all of the blood regurgitates into the left atrium via the foramen ovale and the lungs get perfused retrogradely via a very wide ductus arteriosus.
With an incidence of 3% tricuspidal atresia also belongs to the rare cardiac abnormalities. Through atresia of the tricuspidal valve a connection between the right atrium and the right ventricle is missing. Since this abnormality is mostly combined with a VSD, its effects depend on the size of the VSD.