What is Tetralogy of Fallot?

I had awaited the arrival of my first baby for nine months. My husband and I had been picking out names, buying clothes, decorating the nursery, filling our house with gadgets, contraptions and toys we had no idea how to work. We had been dreaming and hoping and anxiously waiting for this new addition. When our daughter was born, she was absolutely breathtaking! We were amazed at her head of black curls and steel blue eyes. She was alert and we couldn't take our eyes off her. For three days in the hospital, we marveled at every movement, sound, and action she made. On the day of discharge however, we noticed that tests were being run. Not only were tests being run but they were long tests and I felt that something was not right. After bringing my daughter back from tests and telling us we could get her dressed, the nurse also told us that the doctor had heard a heart murmur at birth. These normally clear up but our babies had not. They had made an appointment for us at the local children's hospital with a pediatric cardiologist the following morning. I was stunned. I was frightened. I was confused. This baby seemed so perfect and now we were being referred to the children's hospital, the hospital only serious problems were referred to. I cried all the way home, definately NOT the homecoming I had planned. I cried all night and most of the way to the hospital the next morning. After a half day of tests I had never heard of and X-rays and waiting and not knowing why we were there or what was going on our cardiologist explained that our baby had Tetralogy of Fallot, a congenital heart defect. I sat stunned and felt as though the cardiologist was speaking a different language. EKG's, enlarged heart ventrical, ventricular septal defect, pulmonary stenosis, aorta positioned above septal defect....I didn't understand a word. Those of you who have been in that chair at the pediatric cardiologist understand how confusing it can be. While the terms remain the same, hearing them frequently makes them more accessible over time. From the "laymoms" point of view, this is an unofficial definition of Tetralogy.

What is Tetralogy of Fallot?

Tetralogy of Fallot is a congenital heart defect. Congenital is a term that means existing at the time of birth. Tetralogy of Fallot is characterized by four features. Those features are:

1. Ventricular Septal Defect. This is the medical term for a hole between the ventricles of the heart. The hole is large and is between the bottom ventricles of the heart. This hole allows unoxygenated blood to cross over into the oxygenated blood ventricle. The unoxygenated blood is then pumped throughout the body with the oxygenated blood. This increase in unoxygenated blood causes cyanosis or blue spells or episodes when too much of the blood is unoxygenated.
2. Pulmonary Stenosis. This medical term means that there are obstructions in the path the blood flows from the right ventricle to the lungs. The obstruction usually takes place below the pulmonary valve. This particular malformation is the major cause for all the malformations. The other malformations seem to be compensatory means to give the heart some functionality with the stenosis. Pulmonary stenosis can be severe or mild. The degree of the stenosis will determine the severity and symptoms present in the individual with Tetralogy of Fallot.
3. Overriding Aorta. This malformation is the aorta (the major artery carrying blood from the heart to the body) positioned directly over the ventricular septal defect. This means the aorta is not restricted to the left ventricle alone but has biventricular connections (right and left ventricle connections). Like the stenosis, the degree of the biventricular connections can be mild (5%) to severe (95%).
4. Right Ventricular Hypertrophy. This means the right ventricle or side of the heart is enlarged. Because the right side of the heart has obstructed blood flow from the stenosis, the right side of the heart develops thicker muscles, thus enlarging the right side of the heart. This malformation appears boot shaped in X-rays.

What are the symptoms of Tetralogy?

Tet babies, as they are often referred as, have low blood oxygen saturation. This "low" saturation varies according to the severity of the defect. Generally 95% or above is considered normal. Oxygen saturation (often called "sat" levels) below 90% is generally considered low. These sat levels often drop lower when babies with Tetralogy of Fallot cry or exert. The exertion causes the heart muscle to work harder, thus pushing more unoxygenated blood through the ventricular defect.

Tet babies may also have cyanosis. Cyanosis is a term used to describe the blue appearance of oxygen depleted skin. Babies with severe forms of Tetralogy may appear slightly blue at all times. These babies are sometimes called "Blue Babies". Not all babies with Tetralogy will appear blue however. Some babies only appear blue when exerting themselves during crying spells or physical strain. Others may appear blue only on outer extremities such as fingers and toes or on lips and eyelids. And still others may not have cyanosis at all. Those without cyanosis are called "pink tet".

Other symptoms include heart murmurs which may range from almost imperceptible to very loud, difficulty feeding, failure to gain weight, retarded growth and physical development, and clubbing of the fingers and toes.

Tet spells are characterized by a sudden marked increase in cyanosis, increased heart rate, and syncope. Sudden and severe tet spells can result in hypoxic brain injury causing retardation or developmental learning delays or even death.

Diagnosis

Tetralogy of Fallot is diagnosed by a chest X-ray, which shows the boot shape of the right ventricle of the heart. The most common form of diagnosis is an echocardiogram (sometimes called an Echo). This is similar to an ulstrasound but is done on the heart. The patient lies still while jelly is put on the wand. The professional performing the exam can then capture images of the heart and its functions. No radiation is used adn the procedure is painless to the patient.

For information on treatments see my next hub, coming soon!