I have compiled a post that I hope can explain how Leo’s heart works and what will be taking place in the surgery he will be having soon. This is what we’ve learned about his heart defects so far, but I’m sure we’ll learn even more in the next couple of months!

What is CCTGA? The best explanation I found is from a friend’s blog:

Congenitally corrected transposition of the great arteries (CCTGA), also known as levo-Transposition of the Great Arteries (l-TGA) is when “the blood from the right atrium flows into a left ventricle, which then goes into the main pulmonary artery (MPA), through the lungs, to the left atrium, down into a right ventricle, and out to the body. The blood flow through the heart goes to to where it needs to go, but the ventricles are ‘inverted’, which means that structuarally you have the wrong ‘types’ of ventricles doing the wrong type of work. The pressure on the right side of the heart is low, and a normal right ventricle is designed for low pressure work.

Certainly, the inverted left ventricle, as designed for high pressure work, can handle it. However, the right ventricle on the high pressure left side is not architecturally ready for its long term work to pump blood out to the body. Over time, the left-sided morphologic right ventricle gets thicker, as all muscles do when dealing with higher resistance, but it also dilates. WIth further dilation, it leads to a volume load that stretches the tricuspid valve, causing it to leak. As it leaks, it adds more of a volume load onto the ventricle. Also, as the ventricle dilates, it compresses the right-sided left ventricle, which makes it hard for the heart to pump to the lungs as well. All of this leads to congestive heart failure and poor cardiac output to the body.”

What is a VSD?:

As you can see in the photo above right, a ventricular septal defect (VSD) is a hole in the wall (or septum) that is between the two lower chambers (or ventricles) of the heart. It is also one of the most common heart defects.

“In babies with a ventricular septal defect, blood often flows from the left ventricle through the ventricular septal defect to the right ventricle and into the lungs. This extra blood being pumped into the lungs forces the heart and lungs to work harder. Over time, if not repaired, this defect can increase the risk for other complications, including heart failure, high blood pressure in the lungs (called pulmonary hypertension), irregular heart rhythms (called arrhythmia), or stroke” (CDC).

What is Complete Heart Block?

“There are three types of heart block, depending on the extent of disruption of the electrical impulses: first degree, second degree, and third degree. Also known as complete heart block, third degree is the most severe and represents complete interruption of electrical communication between the atria and ventricles” (CC).

“Complete heart block occurs when the electrical signal can’t pass normally from the atria, the heart’s upper chambers, to the ventricles, or lower chambers” (UCSF).

Leo’s 1st Surgery:

Leo received his 1st surgery on November 30, 2012, only three days after he was born. This surgery was needed to address his heart block, as his heart rate dropped to around 50 bpm. The cardiac surgeon gave Leo a pacemaker, but also put a band around his pulmonary artery to help with the pressures in his heart.

What is an Epicardial Dual-Chamber Pacemaker?

“A pacemaker is a small device that’s placed in the chest or abdomen to help control abnormal heart rhythms. This device uses electrical pulses to prompt the heart to beat at a normal rate” (NHLBI).

An epicardial pacemaker lead is stitched to the outside of the heart muscle, versus an endocardial or transvenous pacemaker in which the leads/wires are inserted through the veins.

A dual chamber pacemaker has 1 lead in the atria (top chamber) and 1 lead in the ventricle (bottom chamber).

“The pacemaker has two parts: the leads and a pulse generator. The pulse generator houses the battery and a tiny computer, and resides just under the skin of the chest. The leads are wires that are threaded through the veins [or on the outside of the heart] into the heart and implanted into the heart muscle. They send impulses from the pulse generator to the heart muscle, as well as sense the heart’s electrical activity” (WMD).

What is a Pulmonary Artery Band (PA Band)?:

The PA band is a constrictive band placed around the pulmonary artery. It reduces the diameter of the pulmonary artery thus restricting the amount of blood pumped into the lungs.

It also prepares and trains the left ventricle for patients with CCTGA who are needing the Double Switch Procedure in the future, by “creating a greater pressure load nearing that of systemic pressure to the naïve LV” (CDN).

Leo’s 2nd Surgery:

Sometime this August, Leo will be having open heart surgery to have several cardiac procedures done. First, the surgeons will remove the PA band. Then he’ll have to close the VSDs. Next they’ll switch the great arteries (aorta and pulmonary artery) to the respective ventricles (arterial switch). Lastly, they redirect the pure and impure blood to the respective normal ventricles by creating a baffle/tunnel (atrial switch or the Mustard procedure).

What happens during a VSD closure?:

“Closing a large VSD by open-heart surgery usually is done in infancy or childhood even in patients with few symptoms, to prevent complications later. Usually a patch of fabric or pericardium (the normal lining around the outside of the heart) is sewn over the VSD to close it completely. Later this patch is covered by the normal heart lining tissue and becomes a permanent part of the heart” (H).

What is the Double Switch Procedure?:

Is an arterial and atrial switch. Here’s a diagram of what happens during the arterial switch:

The atrial “switch”, or Mustard procedure, “employs a baffle [or a tunnel] to direct oxygenated pulmonary venous return into the right atrium and thence into the right ventricle which is the pumping ventricle for the aorta and the systemic circulation”.

“It is an extensive surgery within the atria to create the baffles, which leads to lots of scarring. These scars set up the heart for dysfunction of the sinus node, as well as other tachyarrhythmia (abnormal fast heart beats), such as atrial flutter and fibrillation. The scarring can also lead to obstruction of inflow from the systemic or pulmonary veins. Long term outcome is unknown as the double switch has not been performed consistently well until the 1990s, meaining that good long-term follow-up data is not abundant” (Abi).

So there you have it! That’s just a little glimpse of what is going on inside of Leo’s little heart. Hoping that this will help you know how to pray for the upcoming surgery. It’s pretty complicated, and there are lots of statistics and research papers on the outcome of this surgery, but we know that we can place our fears and anxieties in the One who knows how it will turn out.