Inspired by +Jessica Berman's dedication to raising awareness about the condition.
The term "congenital defect" is just a fancy way of indicating the presence of a structural or functional abnormality in the body that has been there since birth. Since Tetralogy of Fallot deals with the heart it is specified as a congenital heart defect.
Its name comes from the French physician Arthur Fallot (pronounced like fallow in fallow deer) who was one of various doctors who described the condition between the 17th and 19th century.
It is popularly referred to as the "blue baby syndrome", in which the infant or child affected is noted to have a bluish or purplish tinge to the lips or nails. In his famed report "La Maladie bleu" or the blue sickness, Dr. Fallot described four features that characterized the condition:
courtesy: www.sts.org
1. Pulmonary Stenosis
2. Ventricular septal defect.
3. Overriding aorta
4. Right ventricular hypertrophy
Now, in order to understand what these defects are and how they function in producing the symptoms that may alert you as a family member,or family friend, it is important to first understand how the heart works normally, so refresh or make a new memory with my second blog entry about Understanding Your Heart...
Let's begin.
Remember " ...the right half our heart is in charge of pumping blood to and from our lungs in a process known as pulmonary circulation, whereas the left half of the heart pumps blood to everywhere else in our body, including itself in what is called the systemic circulation."
However, the normal pumping process is high-jacked due to the four defects I mentioned two small paragraphs above. To give a wider view, I'll explain the pulmonary stenosis and ventricular septal defect together. Firstly, lets get the definition of pulmonary stenosis out of the way.
Pulmonary stenosis, refers to the narrowing in or around the pulmonary artery. Stenosis is a medical term meaning "the abnormal narrowing of a passage in the body" . From a inside perspective, stenosis of the valves of the pulmonary artery looks like this:
courtesy: standfordchildren.org
The blood that enters the right ventricle is blood that is on its way to the lungs in search to be re-filled by oxygen, however due to narrowing in or around the pulmonary artery the blood is unable to flow as it would if the artery was its normal size.
courtesy: www.marvistavet.com
The added problem to the pulmonary stenosis defect is the fact that, right in the vecinity there is a hole in the wall that should separate the lower chambers of the heart from one another...
The muscular wall between the ventricles is known as the interventricular or ventricular septum.
The ventricular septal defect, is quite literally a hole in between the lower chambers of the heart (ventricles). It can be singular or multiple.
courtesy: 1.bp.blogspot.com
What does this mean as far as the circulation is concerned?
Let me use the analogy of the bus system.
Now, from the blog entry Understanding Your Heart... we learnt that on the right side of the heart we had tired commuters who represented our blood low on oxygen, ready to go home or to the lungs to rest and re-fill on oxygen, but in order to get there there was a particular route they had to take. This was from the Vena Cava, to the Right Atrium, the Right Ventricle and then on to the lungs.
Here I'll add a new bit of info, the final road to the lungs would be through the pulmonary artery. So we now have Vena Cava, Right Atrium, the Right Ventricle, the Pulmonary Artery and then the lungs.
In the case of Fallot's Tetralogy, there are two problems with the final route.
In the case of Fallot's Tetralogy, there are two problems with the final route.
First, there is a road block of sorts. This is the Pulmonary Stenosis Defect (PS), and secondly, in true Antiguan and Barbudan style, there is a massive pothole. This is the Ventricular Septal Defect (VSD). Pardon my doodling :)
What happens next is logical, the bus driver that is, the blood flow, needs to find a new route, and it does, because the aorta, whose correct position in a normal heart is near to the left ventricle (to ensure that oxygen-fresh filled blood is directed to the body), is out of place. This is known as the Overriding Aorta.
In Fallot's Tetralogy, the aorta is near to the ventricular septal defect. This gives the blood flow an alternative route out, to the wrong destination.
The problem is that this easy route is dangerous to the body, because the tired commuters, or oxygen-poor blood are one their way back to work without getting the oxygen needed to be efficient in the body's work.
It is because of this children an infants becaome cyanosed, the blood deficient in oxygen has entered into the systemic circulation without having first gone to the lungs for oxygen renewal.
The heart now has a dilemma, its pumping blood but to the wrong places, and the pathway it needs to function is not as wide as it normally should be, its solution to this?
Pump harder....
This is what causes the last defect in the Tetralogy of Fallot, the Right Ventricular Hypertrophy. This basically means the right lower chamber of the heart, becomes bigger in size as the heart tries to overcome the narrow opening of the pulmonary artery by trying to force more of the oxygen poor blood in at a higher pressure.
courtesy: cias.rit.edu
There it is. The four physical defects of the heart in Tetralogy of Fallot, and how each functions. In the next part I'll give signs and symptoms to look out for in babies and children.
Remember to revise Understanding Your Heart... to see how a normal heart works.
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Check out JJ's Congenital Heart Defect Awareness for Antigua and Barbuda on Facebook.
Stay #wadadlian strong.
Blessings to you and yours,
© January 2015
