Congenital Heart Defects - Forms

2023 Author: Wallace Forman | [email protected]. Last modified: 2023-08-25 11:04

Congenital heart defects: common forms

The spectrum of congenital heart defects ranges from very simple heart defects that have little impact on the cardiovascular system and sometimes even regress on their own to very serious heart defects that, if left untreated, lead to early death. According to the Vienna Children's Heart Center, the most common congenital heart defect is the ventricular septal defect with a share of around 31 percent. All other forms make up well below ten percent.

A distinction is made between three large groups of congenital heart defects, depending on whether and in what type and location there is a short-circuit connection (shunt) between the body and pulmonary circulation.

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• Congenital heart defects without a shunt
• Congenital heart defects with right-left shunt
• Complex heart defects

Congenital heart defects without a shunt

In the case of congenital heart defects without a shunt, oxygen-rich and oxygen-poor blood do not mix:

• Pulmonary valve stenosis: narrowing of the pulmonary artery valve or the outlet from the right main chamber. Depending on the degree of severity, there is increased stress on the right ventricle, which has to fight against increased outlet resistance. This can lead to enlargement and thickening of the right ventricle (right ventricular hypertrophy). The pressure in the right chamber can become higher than the pressure in the system circuit.
• Aortic valve stenosis: The outlet from the heart into the main body artery (aorta) is narrowed. This means that the left ventricle has to do more work to pump oxygen-rich blood into the body. As a result, the heart muscle thickens in the long term (left hypertrophy).
• Coarctation of the aorta : Narrowing of the aorta shortly after the arteries exit to the upper half of the body (aortic isthmus). It mainly loads the left ventricle of the heart, which has to pump the oxygen-rich blood into the ascending aorta and further into the aortic arch. The backwater in front of the constriction leads to increased blood pressure in the upper half of the body. On the other hand, after the constriction, there is low blood pressure, especially in the legs.

Congenital heart defects with right-left shunt

A return flow of oxygen-rich blood forms from the left to the right heart, i.e. from the body to the pulmonary circulation. The right half of the heart is thereby increasingly stressed. Heart defects with a right-left shunt include:

Atrial septal defect (atrial septal defect, ASD)

Hole in the septum between the auricles. Before birth, there is a hole here in all people, the so-called "foramen ovale". This usually closes in the first few weeks of life. In a third of people, a small hole remains open and is called a persistent foramen ovale (PFO). Since under normal circumstances the pressure in the left heart is higher than in the right one, part of the blood flow that was supposed to supply the organism is directed back to the right heart via the defect. This portion of the blood flow subsequently circulates through the pulmonary circulation again and again without being available for the entire organism. At the beginning the children usually have no symptoms,In the long run, however, this can result in an overload of the pulmonary circulation with pulmonary hypertension and a weak heart muscle in the right heart.

Hole in the septum between the auricles. Before birth, there is a hole here in all people, the so-called "foramen ovale". This usually closes in the first few weeks of life. In a third of people, a small hole remains open and is called a persistent foramen ovale (PFO). Since under normal circumstances the pressure in the left heart is higher than in the right one, part of the blood flow that was supposed to supply the organism is directed back to the right heart via the defect. This portion of the blood flow subsequently circulates through the pulmonary circulation again and again without being available for the entire organism. At the beginning the children usually have no symptoms,In the long run, however, this can result in an overload of the pulmonary circulation with pulmonary hypertension and a weak heart muscle in the right heart. Ventricular septal defect (VSD)

Hole in the heart septum, which consists of membranous and muscular components, between the heart chambers. The defect creates a short-circuit connection, via which the oxygen-rich blood flows from the left to the right ventricle (left-right shunt). The right ventricle in particular has to pump more blood volume and blood flow to the lungs increases. In the case of very large defects, the blood pressure in the lungs is also increased; over time, cardiac muscle weakness in the right ventricle can develop. Small defects usually do not cause any symptoms of illness, larger defects burden the circulation and lead to respiratory infections and, especially in infants, to failure to thrive.

Persistent ductus arteriosus botalli (PDA)

The ductus arteriosus (syn. Ductus Botalli) is a small vessel that connects the aorta with the pulmonary artery in the unborn child and which normally closes after birth. If this is not the case, one speaks of an open (persistent) PDA. This is especially true in premature babies. With a large PDA, a lot of blood flows from the aorta into the pulmonary artery. The blood supply to the lungs is increased and the body is less well supplied despite the increased work of the heart. There is an increased strain on the right heart. With some congenital heart defects, an open ductus arteriosus is life-saving because it can be used to mix blood between the body and the pulmonary circulation. It can be kept open after birth by infusing the drug prostaglandin.

The ductus arteriosus (syn. Ductus Botalli) is a small vessel that connects the aorta with the pulmonary artery in the unborn child and which normally closes after birth. If this is not the case, one speaks of an open (persistent) PDA. This is particularly the case with premature babies. With a large PDA, a lot of blood flows from the aorta into the pulmonary artery. The blood supply to the lungs is increased and the body is less well supplied despite the increased work of the heart. There is an increased strain on the right heart. With some congenital heart defects, an open ductus arteriosus is life-saving because it can be used to mix blood between the body and the pulmonary circulation. It can be kept open after birth by infusing the drug prostaglandin. AV canal (atrioventricular septal defect, AVSD)

Malformation of the septum between the atria and ventricles and the AV valves (atrioventricular valves - valves between the atria and ventricles). All of these structures are formed by fusing the so-called "endocardial pillows". If there is no or inadequate fusion, a hole is created in the lower part of the atrial septum and another hole in the upper part of the ventricular septum. Instead of two AV valves, a common AV valve usually has five leaflets. Children with trisomy 21 are particularly often affected. The holes in the heart septum create short-circuit connections from the left heart to the right one (left-right shunt). The common AV valve is often leaky (AV valve insufficiency), which further complicates cardiac function. If the proportion of the ventricular defect is very large,the pressure in the pulmonary circulation increases and the right heart is more stressed.

Note For more information about the heart, see Anatomy and Function of the Heart.

Complex heart defects

The very complicated heart defects are often accompanied by an undersaturation of the blood with oxygen. The patients have a blue color on their lips, fingers and toes (“blue babies”). This so-called cyanosis results from the admixture of oxygen-poor blood in the body arteries and occurs with various heart defects. These newborns require treatment within the first days of life and therefore have a great advantage if the diagnosis was made before birth (fetal ultrasound / organ screening) and the birth takes place in a specialized center.

• Transposition of the large arteries: The large vessels (aorta and pulmonary artery) are swapped: The aorta arises from the right ventricle, so the body only receives the oxygen-poor blood. The pulmonary artery arises from the left ventricle and brings the already oxygen-rich blood back to the lungs.
• Hypoplastic Left Heart Syndrome (HLHS): The entire left half of the heart is underdeveloped and inoperable. The heart valves can be narrowed (stenotic) or completely closed (atretic). The blood accumulates in the left atrium when it can no longer flow into the right atrium via the foramen ovale, which is closed after birth. The right main chamber not only pumps its blood into the lungs, but also into the circulatory system via the ductus arteriosus. If the ductus arteriosus closes, the body's circulation hardly receives any blood and the baby suffers a circulatory shock. If the mistake is not recognized early, the child dies within a short time.

• Fallot Tetralogy (TOF): This heart defect includes the following four changes in the heart:

  • large ventricular septal defect (VSD) = hole in the ventricular septum;
  • Narrow (stenosis) of the outflow path of the right ventricle below the pulmonary artery and / or a narrowing of the pulmonary artery valve;
  • enlarged aorta that “rides” over the ventricular septum defect;
  • thickened muscles of the right ventricle (right heart hypertrophy).

  A so-called right-hand aortic arch is found in up to a third of those affected. The narrower the outflow path of the right ventricle, the more intensely blue the child becomes, as more oxygen-poor blood flows from the right ventricle directly into the main body artery (right-left shunt). The narrowness of the right outflow pathway generally increases in the first months of life. Blue rash (cyanosis) can be seen most clearly on the lips.