Congenitally Corrected Transposition of Great Arteries

It's time for the big one. Congenitally Corrected Transposition of the Great Arteries (ccTGA, LTGA).

In normal, healthy heart there are 4 chambers. Two upper chambers called atria and two lower chambers called ventricles. There is a Right Atrium (RA) that empties to the Right Ventricle (RV), allowing oxygen depleted blood coming back from the body to be delivered to lungs through Pulmonary Artery (PA) arising from the Right Ventricle (RV). Then, through the Pulmonary Veins blood comes back to the Left Atrium (LA) that empties to the Left Ventricle (LV) through the Mitral Valve and then the oxygenated blood goes out to the body through Aorta (AO) arising from the Right Ventricle (RV).

In case of Congenitally Corrected Transposition of the Great Arteries (ccTGA or also called LTGA for Levo Transposition of the Great Arteries) there is an atrioventricular discordance and ventriculoarterial discordance (AV and VA discordance), meaning the Right Atrium (RA) empties to morphological Left Ventricle (LV) through Mitral Valve, from which arises Pulmonary Artery (PA) providing deoxygenated blood (blue) to the lungs. Then the oxygenated (red) blood comes back through Pulmonary Veins to the Left Atrium (LA) and through Tricuspid Valve empties to morphological Right Ventricle (RV) from which Aorta (AO) arises distributing blood to the body.

As you see, both ventricles are switched performing roles they have not been designed for, but due to both main arteries (Pulmonary Artery and Aorta) arising from incorrect ventricles, the correct blood flow through incorrect path is provided.

Here's a nice picture showing both, normal and ccTGA heart described above:

The data shows that about 20% of children born with LTGA is also born with heart on the right side of the body (not left). This is called dextrocardia.

Treatment:

If this is the only defect, surgery may not be required and children with LTGA may potentially live long, normal lives without the need for surgical correction.
They remain under regular care of their cardiologist though, who needs to monitor the heart's condition, since the Right Ventricle (RV), being designed to work under much lower pressure, is now pumping blood to the body, working under approximately 3 times higher pressure. This poses a risk of blood regurgitation through the Tricuspid Valve, weakening of the heart and Complete Heart Block (CHB), in which the contractions of upper and lower chambers are not in synchrony and there may be a need for a pacemaker.
The risk of CHB increases 1%-2% each year.

In case a corrective surgery is needed (due to other defects, or to simply correct the defect and increase chance for long healthy life) a Double Switch (DS) surgery may be performed.

There are different variations of Double Switch; Mustard or Senning.

In Abi's case it was Senning procedure.

You can check out the description of Abi's surgery, including DS and VSD closure here:
Part 1
Part 2

Art

Ebstein's Malformation of the Tricuspid Valve

Today I would like to talk about Ebstein's Malformation of the Tricuspid Valve. One of the defects Abi was born with and which hasn't been corrected yet.

We pray she will never need this corrected and will live full and long life without this every affecting her again.

Ok, so what is Ebstein's Malformation of the Tricuspid Valve?

Tricuspid valve is the inlet valve of the right ventircle that is built of 3 cusps (leaflets), hence the name tricuspid.

This valve lets low-oxygenated blood from right atrium in to the right ventricle (right lower heart chamber). When this valve opens, the blood flows into the ventricle. Then the valve closes, creating a perfect seal and blood is pumped out from the ventricle to lungs through pulmonary valve and pulmonary artery.

When the tricuspid valve is malformed or displaced it means it's located lower than usually and does not seal the ventricle properly, and then we talk about Ebstein's Malformation. In this case, the valve does not seal properly and low oxygenated blood leaks back to the right atrium.

This causes atrium enlargement and leads to congestive heart failure (you will find the symptoms listed at the beginning of the Pulmonary Stenosis post from last week), and build up of fluid in the lungs.

Ebstein's Malformation often is accompanied by ASD (Atrial Septal Defect, a whole between right and left atria, upper heart chambers). This causes the blue, oxygen depleted blood and the red, oxygenated blood to mix. This leads to poor oxygenation, low oxygen levels in the body.

Treatment

Depending on severity the condition may be left untreated and not affect the patient in any major way. It will have to be monitored though.
If the condition is severe it may require surgical intervention, through an open heart surgery.

The cardiothoracic surgeon may be able to fix the valve, reposition the leaflets or may need to replace the valve completely with a cow's or pig's tissue valve, called bioprosthesis.




In Abi's case the valve is lowered and not fully closing causing some mild regurgitation.

Before the Double Switch surgery it was working on the systemic side, performing left ventricle's job, pumping blood to the body at a much higher pressure. This led to much more severe regurgitation and caused multiple problems.

Now, after Double Switch, it's back on the non-systemic side, working under much lower pressure. It is not leaking much, hence it's not affecting Abi in any way at the moment.

It was too risky for Abi to attempt to fix it during the Double Switch surgery, so it was left intact then and, so far, seems like it was a good move.

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Pulmonary Stenosis

Alright, time for another post. For today I picked another of Abigail's heart's complexities, namely Pulmonary Stenosis (PS).

There are several forms of this abnormality and Pulmonary Stenosis may occur in couple different places of the heart-lung circulation system.

Let's start with a short description of what Pulmonary Stenosis means. Basically it means there is an obstruction to the blood flow from right ventricle (right, lower pumping chamber) to the lungs.

Since there's an obstruction, it is harder for the right ventricle to pump the deoxygenated blood to the lungs. Heart needs to work harder, and depending on how severe the PS is, even much harder, leading to congestive heart failure.

Here are couple possible variations of Pulmonary Stenosis.

The most popular, Pulmonary Valve Stenosis occurs when the obstruction of blood flow is caused by the tricuspid valve. The tricuspid valve has 3 leaflets (3 cusps) which open fully when the hurt pumps blood to the pulmonary artery and closes, when the right ventricle relaxes, to avoid a back-flow of blood from pulmonary artery to the heart chamber.

When the tricuspid valve leaflets are fused together, or the valve is malformed and there are 2 cusps (leaflets) instead of 3 (then it's called 'bicuspid valve'), the valve does not open fully, obstructing blood flow.

Subvalvular Stenosis, is a blood flow obstruction that occurs just below the Pulmonary Valve, in the upper part of the right ventricle called the outflow tract. The outflow tract is a muscular tunnel that normally is wide open, unobstructed and participates in pumping blood to the lungs. When the outflow tract is abnormally thickened, it can cause Subvalvular Stenosis, also called subpulmonic or infundibular stenosis (infundibular from the name of the outflow tract muscle- infundibulum).

Supravalvular Pulmonic Stenosis is a narrowing of the Pulmonary Artery just above the Pulmonary Valve.

When the Pulmonary Artery narrows after it branches off to the left and right lung then we talk about Peripheral Pulmonary Artery Stenosis or Branch Pulmonary Artery Stenosis.





Symptoms

Unless the PS is very severe there will be no symptoms, other than heart murmur.

If the PS is severe, it may lead to congestive heart failure and the symptoms I listed in my previous post, Ventricular Septal Defect, but let me list them here too:

- poor feeding
- poor weight gain
- fast breathing even when the baby is fully relaxed and in deep sleep
- excessive sweating
- congestion
- cough

In a very young child it will also lead to cyanosis, blue discoloration resulting from low blood oxygenation.


Treatment

Very mild PS may not require any treatment, but the child will have to be closely monitored by pediatric cardiologist.

Severe PS may require ambulatory or surgical treatment, depending on the severity of PS, placement and overall condition of the patient.

Pulmonary Valve Stenosis can be treated by inserting a small balloon placed at the tip of a catheter through patient's groin area, to the valve and blowing it up, opening the valve. The procedure is called ballon valvuloplasty.

Ballon Valvuloplasty happens under deep sedation and usually patients are discharged from the hospital within 1 to 2 days. If the narrowing reoccurs, the procedure may be repeated, or patient referred to surgery.

Subvalvular Stenosis (obstruction below Pulmonary Valve) or Supravalvular Stenosis (obstruction above Pulmonary Valve) is usually repaired through an open heart surgery after putting the patient on a heart-lung (bypass) machine.

During the surgery the obstructing muscle can be removed, or partially removed, or valve opened, if dealing with fused valve cusps.

When dealing with Peripheral Pulmonary Artery Stenosis, the narrowed artery can be patched, or alternatively a catheter ballon dilation can be performed to stretch the arteries.


Recovery

Unless the child is very sick, the recovery time after the surgery is usually couple days.


In Abi's case, we dealt with Subvalvar Pulmonary Stenosis, since her left ventricle was doing the job of the right ventricle and was on the non-systemic side, the blood was going out through a bicuspid valve. Also, to add to the complexity, her tricuspid valve was malformed (Ebstein's Malformation), which means it was located lower than it should, and it was close to the VSD, causing one of the leaflets to leap through the VSD and further obstruct blood flow to the lungs.

I hope this is a pretty clear and not too long description of Pulmonary Stenosis. There are many great resources out there, if you are interested in getting more in-depth information.

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Ventricular Septal Defect (VSD)

We would like to write couple posts on the heart defects Abi was born with, to break down the complexity of her heart and explain one by one.

Normal Heart:

Let's start with the most common heart defect among newborns, Ventricular Septal Defect, or VSD.

To simplify, heart is built of 4 chambers. The two upper chambers are called the atria (left and right atrium) and the two lower chambers are called ventricles (left and right ventricle).

What is VSD?

It is a hole between the two, lower heart chambers.

Interventricular Septum is the wall of tissue between left and right ventricle (the lower chambers), and when there is a single hole or there are multiple holes in this wall, then we talk about VSD.

There are 2 common forms of VSD:

- Muscular VSD

- Membranous VSD or peri-membranous defect

Muscular VSD means there are holes in the muscle wall all over the septum. As long as the holes are small, there is a good chance they will close on their own, or with help of medications over time, without the need for surgery.

If the holes are large or located in the RV outflow tract then the surgery may be required to prevent the VSD from affecting the nearby aortic valve.

Membranous VSD (peri-membranous defect) occurs close to the aortic and tricuspid valves and the hole does not contain muscle tissue.

In any case, when VSD is present, oxygenated blood from the left ventricle, where there's higher pressure, crosses to the right ventricle. The larger the hole the more blood crosses over.


How is VSD discovered?

Usually within the first couple days or weeks of life, a very soft heart murmur maybe heard. Since for the first couple weeks after birth pressures in lungs and right ventricle are higher, less blood crosses from the left ventricle through VSD, hence the murmur can be very soft or even completely absent.

Once the pressures in lungs and right ventricle get lower to normal, more blood will be crossing between the chambers causing more audible murmur.

For some time the baby may be asymptomatic and if the VSD is small, there's a chance it will close on its own. Usually patients are, or at least should be closely monitored.

If the VSD is large or is not closing on its own, there is a chance the baby will develop a congestive heart failure, also called over-circulation.

Since in Abi's case we already knew about VSD, the murmur was discovered early, but it was not very loud.

The following are signs of congestive heart failure, which Abi was showing as well:

- poor feeding
- poor weight gain
- fast breathing even when the baby is fully relaxed and in deep sleep
- excessive sweating
- congestion
- cough

Depending on the size of VSD the aforementioned symptoms may be more or less severe.


Treatment of VSD

If the VSD is small and there are no symptoms of Congestive Heart Failure, there may be no medical nor surgical treatment necessary and the VSD may close by itself.

If the VSD is larger, medication to strengthen heart and diuretics to help body get rid of water, may be applied. If the medication is helping with controlling over-circulation, there's still a chance VSD will close on its own and no surgical intervention will be needed.

Also increasing calories intake, by adding high calorie formula to breast milk, or using less water with formula may be advised to help the baby gain weight.


Surgery

Surgical intervention to close VSD may be necessary when there are no signs of improvement, no signs of VSD closing on its own.

It may also be recommended when the baby is not gaining weight and the Congestive Heart Failure persist, or there is a risk of a permanent damage to other organs due to VSD.


Recovery

Recovering after surgical VSD closure takes couple weeks, but it's been said the complete recovery process is 6 weeks. After closing VSD (if it was the only heart defect) the baby is considered healthy and should not have any further problems as a result of VSD

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