What is Tetralogy of Fallot?

When our daughter was born, I did not know how common congenital heart defects are, but I now know that 1 out of every 110 babies in the United States is born with a heart defect of some kind. The cause of congenital heart defects is unknown, and in most cases, the heart has already formed improperly before pregnancy is discovered. 

Our daughter was diagnosed with of tetralogy of fallot with pulmonary atresia and atrial septal defect.  It took me weeks to be able to remember those terms without looking at the sheet of paper the doctors had given my husband and me that described her condition. Thankfully, the doctors treating her were all excellent at explaining the situation in terms that we could understand and follow.

To better understand tetralogy of fallot, one must first understand some of the basics of how a healthy heart functions:

  • A healthy heart has four chambers:
    • Right atrium which is where oxygen-poor blood is received into the heart from the body
    • Right ventricle which pumps blood from the heart to the lungs
    • Left atrium which receives blood from the lungs
    • Left ventricle which pumps blood from the heart out to the rest of the body

The atriums are the top chambers and the ventricles are the bottom chambers.

  • The pulmonary artery carries blood from the heart to the lungs. It starts at the bottom of the right ventricle and then splits into two branches which go to the left and right lungs. The pulmonary artery sits in the right ventricular outflow tract.

Tetralogy of fallot is actually a combination of four different defects that are found together in the same patient. In most cases, patients will have three of the four defects, and only in rare cases will a patient have all four. Those defects are:

  1. Ventricular Septal Defect (VSD) – this is a hole in the wall that separates the right and left ventricles
  2. Pulmonary Infundibular stenosis – An obstruction or narrowing of the right ventricular outflow tract
  3. Overriding aorta – In most cases, this means that the aortic valve develops in a way so that it is connected to both ventricles rather than only to the left ventricle as it should be. In about 25% of patients, there will be a right-sided aortic arch, which means that it formed to the right of the pulmonary artery instead of to the left as in a normal, healthy heart.
  4. Right ventricular hypertrophy – this means that the muscle surrounding the lower right chamber becomes overly thickened because of the added work load from trying to maintain a supply of blood to the body

Normally the left side of the heart only pumps oxygenated blood to the body and the right side only pumps deoxygenated blood to the lungs, but with a VSD, blood passes from the right side of the heart into the left side resulting in oxygen-poor blood being sent out to the body.

Atrial septal defect (ASD) is similar to the ventricular septal defect, only it is a hole in the wall between the left and right atriums.

Quite simply, for us tetralogy of fallot with pulmonary atresia and atrial septal defect meant that our daughter’s heart had two holes (ASD & VSD), was missing part of the main pulmonary artery (thankfully her right ventricular outflow tract was normal), and the right branch of the pulmonary artery was narrow. She also had a slight right aortic arch, but did not have the overriding aorta. This combination meant that the amount of blood leaving her heart and reaching her lungs was reduced, and the blood leaving her lungs (oxygenated) and the blood heading to her lungs (deoxygenated) was mixing inside her heart. Then the poorly oxygenated blood was being sent back out to the rest of her body, resulting in her turning blue from head to toe.

All too often, babies born with this problem do not present any signs during their short stay in the newborn nursery, and therefore they get sent home. This results in weeks or months passing before the problem is diagnosed, and in that time, irreparable damage can occur to the brain and internal organs due to prolonged oxygen deprivation. Thanks to one very observant nurse, the problem with our daughter was detected only an hour after birth, so there was no long term damage done to her body from oxygen deprivation.

When our daughter was 11 days old, she underwent her first open heart surgery. Her surgeon performed a “full repair” to correct the tetralogy of fallot by inserting an artificial conduit to act as her pulmonary artery, patching over the VSD, and partially stitching up the ASD. He also corrected her right-sided aortic arch. The ASD was intentionally left partially open to act as a “pop off valve” until the blood started flowing the proper way through her heart. As time goes on, and back pressures cease to be a concern, the hole should finish closing itself off.

The terminology “full repair” is a bit on the deceptive side. While the problems have be addressed and our daughter’s heart has been “fixed” she is not cured.  There is no cure for any congenital heart defect. She will have to have additional surgeries and procedures on her heart throughout her life, and she will always have to have a cardiologist.

February 7-14, 2015 is National Congenital Heart Defect Awareness week.  The goal of this week is to raise awareness of CHDs, because most people do not know the severity of the problem.  I didn’t know until it became a part of my life.  Here are some important facts that you can pass along to help raise awareness:

  • Congenital Heart Defects are the #1 killer of children.  In fact, more children die from CHD each year than from all forms of cancer combined.  Depending on where you get your numbers from, 1 out of every 100, 110, or 125 babies born will have a CHD, and this year approximately 40,000 babies will die before their first birthday.
  • There are roughly 40 different CHDs, and the cause for the vast majority of them is unknown.  In some cases, the cause is genetic, but in most cases, the cause is unknown. 
  • There are no preventative measures that will keep CHDs from happening.
  • About 50% of children with CHD will require at least one invasive surgery in their life, but there is no cure, no permanent fix.  Once you have a CHD, you will always have it, and will require the care of a cardiologist for your entire life.
  • CHD research is extremely underfunded.  According to The Children’s Heart Foundation, only about 1% of all funds received by the major private funder of cardiovascular research goes to any pediatric research.  Without funding, research is slow going, and without research there is no hope for understanding the causes of CHD or of finding a cure.

I saw a post this morning that compared CHD to snowflakes because each child presents their own unique anatomy.  Every VSD is a different size and shape.  Every defect is just as unique as every snowflake.  I like that, it goes a long way to expressing the enormity of the problem.  Please help spread awareness in any way you can.  As we spread the word, the chances of finding a cure increases!