Single Ventricle

What is the heart defect called Single Ventricle ?

While the normal heart has two ventricles, in some birth defects, one of these ventricles may be absent or poorly developed. This condition is called Single Ventricle or Univentricular heart.

The ventricular structure may resemble the normal left ventricle or the normal right ventricle. Sometimes, it resembles neither, and this is called Indeterminate ventricle morphology.

In a single ventricle heart, there are two normal atria – right and left. These open into the ventricle through an atrio-ventricular (AV) valve. There might be
two AV valves, both opening into the ventricle – a condition called Double Inlet Ventricle – or one AV valve only, with the other one being absent (Atresia)

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Tricuspid Atresia – TA

Tricuspid atresia and the Fontan principle are rather complex congenital heart defects. So if you can’t figure out the condition even after reading this article, please understand that this anomaly is so complex that even cardiologists have trouble understanding its repair.

So if you don’t, console yourself that you are in distinguished company!

What is tricuspid atresia ?

Triscupid Atresia is a condition where the Tricuspid Valve, which guards the junction between the right atrium and the right ventricle, is either absent or is imperforate – that is, it does not have an opening to allow blood flow across it. There are many ways the valve can be imperforate – the leaflets of the valve may be formed but tightly stuck to each other, or may not be formed at all, with muscle tissue of the heart forming a wall where the valve should have been.

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Pulmonary Stenosis – PS

Pulmonary Stenosis (PS) is one of the simpler abnormalities of the heart. But even this requires some basic knowledge about the structure of the heart.

What is Pulmonary Stenosis ?

The word “pulmonary” denotes “to do with the lungs”.

The pulmonary valve is located between the right ventricle and the pulmonary artery. It regulates blood flow into the lungs, and prevents blood from leaking back into the right ventricle.

Sometimes, this pulmonary valve is extremely narrow, and blocks the smooth flow of blood into the lungs. This condition is called Pulmonary Stenosis – or PS, in short.

At other times, the pulmonary valve itself is normal, but there is an obstruction to blood flow from the right ventricle at other levels. For instance, there may be abnormal bundles of muscle below the pulmonary valve which obstruct flow. This is called “sub-valvular” pulmonary stenosis.

Or occasionally, there may be a narrowing of the pulmonary artery or its branches above the pulmonary valve. This is called “supra-valvular” pulmonary stenosis.

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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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Hypoplastic Left Heart Syndrome – HLHS

The “Hypoplastic Left Heart Syndrome” – or more conveniently, “HLHS” – is a unique defect of the heart in many ways. Until a decade ago, the diagnosis was a virtual death sentence. Today, the revolution in cardiac surgical thinking and technique has changed the situation radically.

Whereas survival beyond the first few months of life was previously unheard of, many centers are today reporting encouraging results. And it is bound to improve further as more knowledge is gained from the early experience.

What is the HLHS ?

The heart has two upper and two lower chambers – one of each is right sided and the other left sided. The left sided chambers, with their blood vessels and valves are sometimes referred to as the LEFT HEART. ( This does not mean that the person has TWO hearts! )

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Ebstein’s Anomaly

What is Ebstein’s anomaly ?

It was in 1866 that Ebstein first described the heart defect that bears his name. The defect includes the following components:

  • Displacement of the tricuspid valve (that lies between the right atrium and right ventricle) leaflets downwards from it’s normal position.
  • Abnormalities of the right ventricle
  • “Atrialization” of a portion of the right ventricle
  • An inter-atrial septal defect (ASD)

What happens in Ebstein’s anomaly ?

The primary problem is displacement of the tricuspid valve down from the normal position, which in turn results in the abnormal valve becoming leaky. This valve leak, combined with right ventricle muscle abnormalities, causes heart enlargement with heart failure, along with a “shunt” of blood from the right atrium, across the ASD, into the left side of the heart and circulation.

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