Ventricular Septal Defect (‘hole in the heart’) - By Jasmine Fox

During my AS biology lessons at school I took particular interest in the biological basis of the heart, and particularly the basis of Coronary Heart Disease, so I wanted to learn further about other illnesses in relation to the heart and its function. Having heard about babies being born with 'a hole in their heart' yet leading a normal life, I was curious to find out how this was possible. So I spent time researching further to produce a presentation about them for our school's medical society.

I discovered that they are called 'Ventricular Septal Defects', VSDs and that they're the most common congenital heart defect, being found in 2-6/1000 babies at birth. A simple description of them would be an opening in the ventricular septum (between the left and right ventricles); they vary in size and are found in different places along the ventricular septum. 

So I decided to approach the defect from the start by looking at its cause. I found that in the first few weeks after conception the heart divides from the large tube into sections, which produces the walls and chambers. But, if a problem occurs in this process, a hole can be created. There is, however, mostly no clear cause for this problem arising. On the other hand there are risk factors that increase the tendency to develop a VSD; one example of this is genetic syndromes. But there are also other risk factors:
•The mother having the rubella infection during pregnancy, this can spread into the foetus' circulatory system, damaging the foetus' blood vessels and heart.
•The mother having uncontrolled diabetes, which affect the foetus' blood sugar levels, causing damage.
•The mother taking drugs, drinking alcohol, smoking or being exposed to radiation are all also risk factors for causing harm to the foetus.

Next I looked for information about the pathway of the defect and why it causes problems. In normal heart function the left ventricle has to contract stronger than the left as it has to pump blood all around the body (not just to the lungs), this produces a high pressure in left ventricle, causing some oxygen enriched blood to flow into the right ventricle from the left, through the hole in the septum. In the right ventricle this oxygenated blood to mix with oxygen poor blood, then returning to the lungs. This creates extra noise, which is detected as a heart mumour by the doctor using a stethoscope. The heart mumour will be detected during the first few weeks of life in a routine check-up, as holosytolic/ pansytolic, and is best heard over the third and fourth intercostal spaces, and along the sternal border. The paediatrician who hears the mumour will refer the baby to a paediatric cardiologist, who will carry out many tests to gain more information about the VSD:

•A chest X-Ray, which takes a picture of the heart and surrounding tissues.
• An electrocardiogram which records the electrical activity of the heart. Which mirrors the size of the shunt, and the degree of pulmonary hypertension (how much the blood pressure is raised. 

--A medium VSD is indicated by a broad notched P wave (due to a left atrial overload), as well as deep Q as well as tall R and T waves in V5 and V6 (showing left ventricular overload).
--A large VSD can be shown by right axis deviation (indicating right ventricular hypertrophy, thickening of the right ventricular walls, as it has to contract harder to pump and increase volume of blood - both oxygenated and deoxygenated).
•An echocardiogram, which is the primary tool of VSD diagnosis. This shows the sound waves, which produces an image of the heart, allowing the specialist to visualize the blood flow through the heart chambers, so the irregular flow of blood between the ventricles can be seen.

Following this I researched further into the symptoms that arose from a baby having a VSD, and learned how small sized VSDs in fact don't typically cause symptoms, and that they don't cause many issues, and even have little effect on exercise, ultimately perhaps close on their own. 
This is very different, however, for moderately sized or large VSDs, causing noticeable symptoms, such as: babies breathing faster; babies being tired, sweating, crying during feeding attempts; they may also gain weight at a slower rate. These symptoms indicate that the hole is probably too large to close by itself and cardiac surgery is required within the first three months. Surgery for Ventricular Septal Defects can be done in many ways:

1. The surgeon makes an incision in the chest wall, and directly stitches over the hole.
2. The surgeon sews a patch of manmade surgical material over it, the heart tissue then heals over the patch and stitches. Therefore, after 6 months the hole is completely covered with tissue.
3. A catheter (a small, thin, flexible tube) is inserted into a blood vessel in the leg (which connects to the heart), and the tube is then guided to the heart. A special implant of two disks of flexible wire mesh is transported through the catheter and is positioned into the hole, being flattened against the septum on both sides, closing and sealing the VSD. 

To me the idea that we can be born with holes (however small) in our tissues and our body, whilst so young, is able to fix these, in a relatively short amount of time, I find fascinating. And find is especially pleasing that we are now able to seal the slightly larger holes, with less risk to the baby than previously existed, and heightened by the idea that most babies used to die who had VSDs when no surgery was available, whereas now the death rate is very low.

These continuous advances in medicine are one reason for why I want to go on to study it at university, and as a doctor have the chance, and ability, to carry out these very specific and technological operations. I would love the opportunity to learn new techniques and knowledge about many diseases researched every day, and be able to save many lives through my everyday work. 

I hope that from reading this you have gained a greater knowledge of the defect and are as enthusiastic as I am, and the other members of Queen's medical society are for finding out more. I will try to answer any questions that you leave as comments.
Thank you for reading my article.

Jasmine Fox