Monthly Archives: Apr 2003

Transposition of Great Arteries – TGA

Transposition of Great Arteries - TGA

I hope you still remember about the great arteries of the body, and the chambers of the heart from which they arise. In this article, we will discuss the condition called Transposition of the Great Arteries (TGA) in which these great vessels are inter-changed in position.

Here’s what you’ll learn about:

  • What is Transposition of the Great Arteries (TGA) ?
  • What happens in TGA ?
  • What if TGA is left untreated ?
  • When should TGA be treated ?
  • What are the treatment options ?
  • Initial stabilization
  • Palliative treatment
  • Definitive treatment
  • Arterial Switch Operation (ASO)
  • Atrial Switch Procedures
  • Some Special Circumstances

What is Transposition of the Great Arteries?

The two “great” arteries of the body are the aorta and the pulmonary artery. The aorta comes out of the left ventricle, and carries pure blood to the rest of the body. The pulmonary artery arises from the right ventricle and carries impure blood from the veins into the lungs for oxygenation.

Transposition of the Great Arteries – TGA, for short – as the name implies, means the two arteries are “transposed”. That is, the aorta arises from the right ventricle, and the pulmonary artery from the left ventricle.

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Tetralogy of Fallot – ToF

Tetralogy of Fallot - ToF

We’re now getting to a more complicated condition called the Tetralogy of Fallot – or ToF, for short. The diseases discussed until now had just one abnormality in the heart – Atrial Septal Defect (ASD) or Ventricular Septal Defect (VSD) or Patent Ductus Arteriosus (PDA).

As the name tetralogy implies, there are FOUR abnormalities combined together in this complex heart defect. ToF is also commonly called the “blue-baby” disease.

In this article, you’ll learn:

  • What are the components of ToF?
  • Why is it called “Blue Baby Disease”?
  • What exactly happens in ToF?
  • What is a “cyanotic spell”?
  • What happens if ToF is left uncorrected?
  • What are the surgical options?
  • How is a single stage intra-cardiac repair done?
  • Variations in ToF needing modified repair
  • What is an “outflow patch”?
  • When is an intracardiac repair NOT possible?
  • What are the palliative operations for ToF?
  • The Blalock-Taussig shunt
  • Other systemic-pulmonary shunt procedures
  • What is the outcome after a total correction operation?
  • What is the future course after a shunt procedure?

Basics of Tetralogy of Fallot

What are the four components of ToF ?

1. The first is a Ventricular Septal Defect – or VSD.

2. Next is a narrowing of the Pulmonary Valve, which guards the junction of the right ventricle with the pulmonary artery. This narrowing is called Pulmonary Stenosis (PS).

3. The third feature is a thickening of the wall of the right ventricle (RV). This increases the strength of the right ventricle and helps it pump blood more forcibly. This thickening is called RV Hypertrophy.

4. And the last component is an over-riding aorta.

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Patent Ductus Arteriosus – PDA

Patent Ductus Arteriosus - PDA

As you already know about the large blood vessels – the aorta and pulmonary artery – it’s easy to learn about the birth defect called Patent Ductus Arteriosus (or PDA).

What is a Patent Ductus Arteriosus?

As a child develops inside its mother’s womb, it is not able to “breathe”. So, even though the child’s lungs are well developed, they do not carry out their normal work.

The blood which flows through the right ventricle and pulmonary artery to the lungs has no function. It is “wasted” blood flow.

In an attempt to make use of this flow, nature provides man with a “shunt” or “bypass”. A small tube, or blood vessel, connects the pulmonary artery to the large artery called the aorta. This tube is the ductus arteriosus.

Through this tube, blood which enters the pulmonary artery, instead of going to the lungs, flows into the aorta. From the aorta, the blood reaches other parts of the body. It is now useful to these other parts, which get energy to do their work.

At birth, when the child draws its first breath, the lungs begin to work. Now, when blood flows into the lungs, it is mixed with oxygen and “purified”. At this time, the ductus arteriosus normally closes. At first, it closes by spasm or contraction of the muscle in its wall. Later, the tube becomes permanently blocked by a scar.

Sometimes, it does not close normally. It then remains open, and the condition is called Patent Ductus Arteriosus – or PDA.

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