- In this condition, there is a congenital heart defect involving 4 abnormalities of the heart. All tetralogy children are not alike, mainly because the size of the 4 abnormalities and their exact position, influences the amount of illness, and influences whether the child will have central cyanosis (blue lips).
- The four abnormalities (feel free to skip to causes, if you wish):
- The blood ejected from the right side of the heart (ejected from the right ventricle into the pulmonary artery and then into the lungs) passes out of the right heart through an abnormally narrow doorway, or gets to a doorway that isn't formed yet (the pulmonary valve). Another variation of the same problem is that the doorway (pulmonary valve) might be normal in size and not narrow, but the artery that takes blood away from the right side of the heart (and sends that blood to the lungs) might be the narrow part.
- There is an abnormal hole between the right and left ventricles (the bottom chambers of the right and left side of the heart) called a VSD. If blood cannot escape from the right side of the heart because the pulmonary valve isn't formed yet, it can escape through the VSD into the left side of the heart.
- Over-riding aorta: this large artery is supposed to transport blood leaving the left side of the heart, out to the head and the body.
- In TOF, the aorta might be large enough to extend a little bit onto the right side of the heart and transport some of the blood leaving the right side of the heart as well. However, this is not always the case. Sometimes, part of the aorta angles toward the right, but does not actually pick up any blood that would leave the vicinity of the pulmonary valve.
- If the pulmonary valve area isn't formed yet, blood reaches the aorta by escaping the right side of the heart through the VSD. Once the blood is in the left side of the heart, it passes into the aorta.
- Since there would be no way,
ordinarily, for blood in the aorta to pick up needed
oxygen from the lungs, in TOF there are often arteries
that leave the aorta and go to the lungs to pick up
oxygen. Veins then bring this oxygen back to the
- Thickening of the wall of the
right ventricle: this part of the right side of the heart
ejects blood through the abnormally narrow doorway, called
the pulmonary valve (or ejects blood into the abnormally
narrow pulmonary artery). Since the heart is a
muscle, the right ventricle, which is muscle, enlarges and
thickens when it exercises severely (trying to eject blood
through a narrow doorway, or into a narrow
- For simplicity's sake, many physicians state that the essential elements in TOF are the pulmonary valve/pulmonary artery narrowing, and the VSD.
- This explains the symptoms in a general way, but it is not specific to any one child.
- Non-cyanotic tetralogy: (why the
baby is not blue)
- In a simplified way of expressing this, blood has 2 opportunities to pick up oxygen from the lungs; the first time: that the right side of the heart pushes the blood to the lungs; and the second time: that blood enters the right side of the heart from the left side (namely, through the VSD hole).
- The baby with this kind of tetralogy might not be cyanotic. Also, if several arteries branch off the aorta and go to the lungs, and then bring blood back to the heart, the body gets oxygen in this unusual way (and the baby might not be cyanotic). However, most TOF babies eventually have cyanosis.
- Cyanotic tetralogy: (why the baby is blue)
- In a simplified way of saying
this, if the blood in the right side of the heart flows through an unnatural hole (VSD) into the left side of the heart, this blood bypasses the lungs and does not pick up oxygen, even though this blood is very oxygen-depleted. This might happen if there is no pulmonary valve opening.
- The baby with this kind of tetralogy is likely to be cyanotic (blue).
- Non-cyanotic tetralogy:Heart Murmur (noise in the heart)
usually present in the babies, although it may be a very soft
noise and hard-to-hear with a stethoscope. TheHeart Murmur may
be a very brief and a very soft noise, not a prominent part of each heartbeat . Therefore, doctors may not realize in the newborn nursery that this baby has TOF. Congestive heart failure may occur later, with shortness of breath and a rapid pulse.
- When physicians use the phrase "non-cyanotic tetralogy," they are almost always referring to a heart that has just 2 of the 4 abnormal components: the VSD and only a mild to moderate pulmonary valve narrowing. This is a much more common use of the phrase, "non-cyanotic tetralogy" than to actually mean babies who have all 4 components abnormal.
- Cyanotic tetralogy: the babies often do not show cyanosis until around 6 months of age, and then cyanosis becomes more severe. They act sickly, even as small babies, with shortness of breath after feedings or after exertion.
- The babies who have severe blockage of any blood flow to the lungs can only get a small part of the needed amount of oxygen into their bloodstream, and those infants are cyanotic right from birth. In older, ambulatory children with cyanotic TOF, they have a habit of squatting like a baseball catcher, which reduces the amount of blood returning from the legs to the heart. This allows the blood in the chest to have a longer time to pick up oxygen from the lungs, before the returning blood from the legs displaces it.
- These cyanotic infants or children also have many spells with fast breathing and turning more and more blue. Often, they lose consciousness during these spells. These spells are fairly dangerous because they can result in a stroke.
- Usually these cyanotic infants or children have limited ability to exercise because they become short of breath on exertion.
- This explains the diagnosis in a general way, but is not specific to any one child.
- Non-cyanotic tetralogy: this condition
may be difficult to diagnose until the child becomes cyanotic,
because there may be no clues except a very soft heart murmur ( a very soft noise in the heart ). If a
chest X-ray were done, it often would show little blood flow
to the lungs, and a particular shape to the heart. If
an electrocardiogram were done, it often would have a
particular pattern that indicates the right side of the
heart is enlarged.
- Non-cyanotic tetralogy usually refers to Congenital Heart Disease that has just 2 of the 4 components: the VSD and only a mild to moderate pulmonary valve narrowing.
- Cyanotic tetralogy: This is usually diagnosed by the cyanotic spells coupled with a chest X-ray that has little blood flow showing in the lungs, and shows a particular shape to the heart. An electrocardiogram is also helpful, because it has a particular pattern that indicates the right side of the heart is enlarged.
- This explains the treatment in a general way, but it is not specific to any one child.
- Non-cyanotic tetralogy: these infants and children (if they have all 4 components of the tetralogy) usually become cyanotic and then need surgery to correct the tetralogy.
- Antibiotics before dental surgery and before certain other procedures
- However, it was explained under symptoms and diagnosis, that non-cyanotic tetralogy usually refers to Congenital Heart Disease that has just 2 of the 4 components:
the VSD and only a mild to moderate pulmonary valve
narrowing. These children might never become
cyanotic and might have corrective surgery delayed until
they become symptomatic.
- Cyanotic tetralogy: Under the age
of 2 years, a surgical procedure is usually done to partly
correct the tetralogy until the child is old enough to
tolerate a complete corrective surgery. In some
medical centers, the entire correction is done in one
procedure instead of two, but this concept is
- When cyanotic TOF infants start to have "blue spells" the parents learn to place the baby on his belly, bring the baby's knees up toward the chest (similar to squatting), give oxygen, and keep the baby calm. These "blue spells" often need emergency medicines as well.
- Antibiotics before dental surgery and before certain other procedures
- This explains the complications in
a general way:
- Short stature and being underweight
- Anemia (low red blood cell
- Stroke (cerebrovascular accident) or brain abscess (a pus collection in the brain)
- Bacterial endocarditis (infection of a heart valve)
- Keep in mind that heart murmurs heard in the newborn nursery might turn out to be tetralogy, even if the baby does not have cyanosis. If your baby is a poor feeder or gets short of breath with feedings or exertion, this might indicate a medical problem such as Congenital Heart Disease.
- If your baby or child ever has "blue spells," bring this to your doctor's attention immediately, or call 911.
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