Cyanotic Congenital Birth Defects
Types of Cyanotic Congenital Defects
Tetralogy of Fallot
Tetralogy of Fallot, or TOF, is the most common forms of complex congenital heart defects that causes cyanosis, also known as "a blue baby". It accounts for approximately 10% of all congenital heart disease.
Tetralogy of Fallot is comprised of four different components. The first component is a ventricular septal defect (VSD). The second component is pulmonary stenosis (PS). The third component is right ventricular hypertrophy, which is an increase in the size of the right ventricle. The final component is an overriding aorta (Ao), which means that the aorta lies directly over the ventricular septal defect.
The ventricular septal defect is usually large. Blood flows from the right ventricle through this VSD into the left ventricle. This occurs because of the resistance of blood flow through the pulmonary valve. Once the blood flows into the left ventricle, it is ejected into the aorta and delivers de-oxygenated blood into the body. Because there is de-oxygenated blood being delivered to the body, these babies may appear cyanotic, or "blue". Cyanosis may increase in severity with crying, agitation or bowel movements.
Open heart surgery is needed to correct this defect.
Transposition of the Great Vessels
In this congenital heart defect, the aorta (the main artery that carries blood to the body) originates from the right ventricle and the pulmonary artery from the left ventricle, resulting in two separate circulations.
In this condition, the arteries are reversed and the aorta carries blood from the right ventricle. In order for the infant to survive, they must have some communication between the right and the left sides of the heart to allow oxygen rich blood to reach the body. This mixing of blood is possible through any of the following: ASD, VSD, PDA. Even though there is mixing of oxygenated and de-oxygenated blood, it is often not adequate to sustain life for an extended period of time. Babies with transposition are extremely blue at birth.
The most common surgical procedure to correct this defect is called an arterial switch operation. That is, the major arteries are "switched". The aorta is connected to the left ventricle. This allows oxygen rich blood to be pumped to the body. The pulmonary artery is connected to the right ventricle. This allows low oxygen blood to go to the lungs where it can be oxygenated. Other surgical defects may also be needed to correct the communication between the left and right sides of the heart.
This is the second most common congenital heart disease encountered in early infancy.
Total Anomalous Pulmonary Venous Return
In total anomalous pulmonary venous connection, the pulmonary veins drain into the right atrium instead of the left atrium. In order for the infant to survive, they must have communication between the right and left sides of the heart. This communication is needed to allow oxygenated blood to reach the body. This disruption in communication is always an Atrial Septal Defect (ASD), although a Ventricular Septal Defect (VSD) may be present as well. Because the oxygenated blood is so dilute, the infant may appear blue or "cyanotic".
There are three main types of Total Anomalous Pulmonary Venus Return. The different types depend on where the pulmonary veins drain. They are referred to as supracardiac, intracardiac, and infracardiac. There may also be a mixed type, in which two or more types may coexist.
In order for the infant to survive, open heart surgery is needed in early infancy. The surgery involves removal of the pulmonary veins from the right atrium and anastomosis to the left atrium. The ASD is also closed, along with the division of any abnormal connections that may be present.
In Truncus Arteriousus, only one artery originates from the heart. This originating artery forms both the aorta and the pulmonary artery. The truncus arises above a Ventricular Septal Defect that is almost always associated with this defect.
The truncus receives low oxygen blood from the right ventricle and oxygen rich blood from the left ventricle. This mix of high and low oxygen blood is sent out to the body and the lungs.
Open heart surgery in infancy is needed to correct this defect. The surgery involves closure of the Ventricular Septal Defect and removal of the pulmonary arteries from the truncus. The pulmonary arteries are then connected to the right ventricle with a prosthetic tube. This prosthetic tube usually needs to be replaced as the infant grows.
Tricuspid atresia means that the tricuspid valve in the heart didn't develop normally. As a result, the right ventricle may also not develop, and hence there is usually only a single ventricle.
Because there is no tricuspid valve, blue blood returning to the heart from the body cannot enter the right ventricle. This blue blood then shunts across an atrial septal defect to the left atrium, and mixes with the red blood returning from the lungs. The mixture of blue and red in the left atrium enters the single ventricle, and from there is ejected into both the aorta and the pulmonary artery.
Hypoplastic Left Heart Syndrome
Hypoplastic left heart syndrome, or HLHS, means that the entire left side of the heart did not develop normally. Therefore, the mitral and aortic valves are tiny or absent, as are the the left ventricle and the first part of the aorta.
HLHS is not a survivable lesion without major open heart surgery. There are two types of heart surgeries that will help this condition: cardiac transplantation and staged palliation. In cardiac transplantation, the entire heart is replaced by a donated heart. Staged palliation is a little more complexed. Your doctor should advise you about the risks and benefits to each of these two options.
For HLHS, staged palliation involves three operations. They are Norwood operation, Bidirectional Glenn Operation and Fontan Operation. The Norwood operation is performed immediately after birth, and converts the right ventricle into the main, or systemic ventricle. The bidirectional Glenn operation is done next, and diverts half of the blood returning from the body to the lungs. It is typically done at about six months of age. The Fontan operation is the last stage of the staged palliation, and diverts all of the blood returning from the body to the lungs. It is typically done around 2 years of age. The timing of these operations is variable, and depends on many clinical and social factors.
Staged palliation for HLHS is one of the great achievements of congenital heart surgery in the 90's. In what used to be a uniformly fatal disease, consider the following: Survival following a Norwood operation is around 80%, following a bidirectional Glenn operation around 100%, and following a Fontan operation around 95%. Overall, survival at 5 years of age is around 70 - 75%. Most patients who get through the three stages do quite well: Very few are on medications, almost all have normal growth and development, and very few have any exercise or other kinds of limitations.
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