Hypoplastic Left Heart Syndrome – HLHS

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! )


Ebstein’s Anomaly

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.


Double Outlet Right Ventricle – DORV

Double Outlet Right Ventricle DORV

What is Double Outlet Right Ventricle (DORV) ?

Some of the defects I have described are “simple”, some are a little “complex” – but DORV is something else.

It is a common term that actually describes a wide spectrum of heart disease, ranging from something similar to a Ventricular Septal Defect (VSD), through Tetralogy of Fallot (ToF) to Transposition of the Great Arteries (TGA).

It is sometimes like one, at other times like another, and occasionally a mixture of some of them. So if at first you are baffled, don’t worry. I too was, and figured it out only after a long hard struggle.

What is Double Outlet Right Ventricle ?

Normally, a ventricle has just ONE outlet. For the left ventricle, this is the aorta. For the right ventricle it is the pulmonary artery. In DORV, both of these “outlet” blood vessels – aorta and pulmonary artery – arise from the RIGHT VENTRICLE, either totally or to a great extent.


Coarctation of the Aorta – CoA

Coarctation of the Aorta - CoA

You have read something of congenital heart defects inside the heart. Now let us consider a defect that is outside the heart itself, in one of the great arteries of the body – the aorta.

What is COARCTATION of the aorta ?

Coarctation of the aorta (CoA) is an area of localized narrowing of the large artery called the aorta. (“Coarctatio” – Latin : a drawing or pressing together). The narrowing may be caused by a “shelf” of tissue inside the blood vessel which reduces its area. Alternately, it may be caused by under-development of a portion of the aorta itself, which causes a longer area of reduced diameter.

Where does CoA occur ?

The narrowing that occurs in CoA is most commonly seen at a portion called the ISTHMUS.

But what is the isthmus ?


Ventricular Septal Defect – VSD

Ventricular Septal Defect VSD

What is a Ventricular Septal Defect?

Ventricular septal defects – also called VSD – are similar to ASD.

A VSD is a “hole” in the wall between the two lower chambers of the heart – the ventricles.

VSD may be small, medium-sized or large, and may be single or multiple. It may occur in different parts of the ventricular septum, and may sometimes be found along with other heart defects.

What happens when there is a VSD ?

The wall between ventricles is meant to separate blood passing through each. This is to prevent mixing of “impure” blood from the veins with “pure” blood going to the arteries. When the wall is “broken”, mixing occurs.

However, only “pure” blood flows from the left ventricle into the right; no flow is seen from the right ventricle into the left side across the VSD and so “impure” venous blood does not reach the arteries. This is because pressure in the left ventricle is much higher than the right, and fluids always flow from places of high to lower pressure.

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