Heart abnormality with left-right shunt (acyanotic)
With a left-right shunt an increased pulmonary perfusion to the detriment of the systemic circulation system is the result. Shunts from the oxygen-rich side to the oxygen-poor side are not usually accompanied by a cyanosis.
Persisting ductus arteriosus (PDA)
The ductus arteriosus connects the pulmonary artery with the aorta. Prenatal it is a vital structure to have. After birth, in the first days of life, though, the ductus arteriosus is closed by the active contractions of its smooth muscles, followed by an intima proliferation. The sealing of the ductus is triggered by the postnatal pO2 increase due to the breathing of the newborn.
A persisting ductus arteriosus (PDA) is spoken of when the normal, postnatal closure fails to take place (ca. 9% of all cardiac abnormalities). In hemodynamic terms, the quantity of blood flow due to a PDA depends on the diameter and length of the ductus arteriosus. In addition, the size of this left-right shunt varies with the pulmonary resistance. Since in the first 3-8 weeks after birth this resistance decreases continuously, a cardiac insufficiency may occur.
Atrial septum defect (ASD)
Prenatally an ASD is of no hemodynamic importance because the foramen ovale is already open normally and directs the blood from the inferior vena cava to the left side of the heart. Only after birth does it have hemodynamic consequences in that a left-right shunt arises due to the different pressures in the two atria. Its incidence amounts to 11%.
The ASD leads to a left-right shunt and to an overload for the right ventricle with recirculation through the lungs.
Ventricle septum defect (VSD)
Ventricular septum defects are encountered relatively frequently (28% of all congenital cardiac abnormalities). They can occur by themselves but also combined with other defects.
Prenatally, even a large defect is not disadvantageous because roughly the same pressure is present in both ventricles. Postnatally, the severity of the VSD depends on its size and the resistance relationships in the pulmonary and systemic circulation systems. Small defects lead to no detriment and especially those in the muscular septum sometimes close spontaneously.
, according to the clinical picture, of the diagnostic possibilities as well as the therapy.
Atrioventricular septum defect
Here a part of the atrium as well as a part of the ventricular septum are missing. This probably results from an abnormal fusion of the dorsal and ventral av-cushions in the early embryonic development (stages 16 - 18). The clinic adjudges according to the size of the defect. It should also be mentioned that this is the most frequently occurring cardiac abnormality in patients with Down syndrome.