Congenital Heart Disease in Children

CHD is an abnormality of the structure of the heart that exists at birth. It occurs when the heart or major blood vessels fail to develop or mature normally during the pregnancy.

The list below describes some terms commonly used in CHD:

• Stenosis – narrowing
• Atresia – absence of
• Atrium and Ventricle - there are four chambers in the heart; both right and left having two each, one sitting above the other. The top chamber is called an atrium while the bottom chamber is called the ventricle.
• Mitral valve – this is the opening between the top and bottom chambers in the left side of the heart and acts as one-way valve.
• Tricuspid valve – this is the opening between the top and bottom chambers in the right side of the heart and acts as one-way valve.
• Aortic valve – this is the opening that connects the left ventricle of the heart with the aorta, which is the major blood vessel that delivers oxygenated blood to the rest of the body. It acts as one-way valve.
• Pulmonary valve – the valve in the opening that connects the right side of the heart to the vessels that delivers the used, oxygen depleted blood to the lungs. It acts as one-way valve.
• Septum – the wall that divides the right and left sides of the heart; the wall that divides both the atria is called the atrial septum and the wall that divides both the ventricles is called the ventricular septum.

There are many different types of CHD that fall into four common categories of congenital defects:

This occurs when either abnormally formed heart valves or major blood vessels block the flow of blood into or out of the heart such as:

• Congenital aortic stenosis
• Mitral valve stenosis
• Pulmonary valve atresia/stenosis
• Absent pulmonary valve syndrome
• Coarctation of aorta
• Interrupted aortic arch

In a normal heart, the heart is made up of four chambers, two on either side, left and right. In simple terms, the left and right side of the heart are kept separated. The right side of the heart is responsible for receiving "used" blood (blood with reduced oxygen, which is blue) from the rest of the body and delivering it to the lungs. The left side of the heart is responsible for oxygen-rich blood (red blood) from the lungs and sending it out to the rest of the body.

However, in left to right shunt types of CHD, the blood flows from left side of heart into right side of heart. This is due to abnormal connection between right and left side of the heart. This results in the right side becoming overloaded with an "extra volume" of blood. When this happens, it results in too much blood flowing into the lungs.

Conditions where this occurs are as follows:

• Patent ductus arteriosus (PDA)
• Septal defects such as:
  • Atrial septal defect (ASD)
  • Ventricular septal defect (VSD)
  • Atrio-Ventricular defect (AVSD)
  • Aorto-pulmonary window

In right to left shunts, the blood now flows from the right side of the heart to the left. This is also due to abnormal connection between the right and left side of the heart. It results in a decreased flow of blood into the lungs, which means that the amount of “used”, or oxygen depleted blood pumped into the lungs to be re-oxygenated reduces. This condition is also called “cyanotic heart disease” as this condition causes a bluish colour of the skin (usually in the tip of fingers and toes) and mucous membranes (lips) due to low oxygen levels in the blood.

Conditions where this occurs are as follows:

• Teralogy of Fallot (TOF) which comprises four abnormalities:
  • VSD
  • Over-riding of the aorta
  • Pulmonary stenosis
  • Right ventricular hypertrophy
• Pulmonary atresia with intact VSD
• Pulmonary atresia with VSD
• Tricuspid atresia
• Ebstein's anomaly

These defects have more than one defect and are also known as “mixing defects”.

• Double outlet right ventricle
• Univentricular heart
• Total anomalous pulmonary venous connection
• Truncus arteriosus
• Hypoplastic left heart syndrome
• Transposition of Great Arteries (TGA)

Medical and surgical treatments now offer these children an opportunity to grow and mature into adult life, an option that was not available in the past.

The presenting features of CHD depend on the age of your child and the type of defect present.

Common presenting features include:

• Failure to thrive (inability to grow) in small infants/newborns
• Cyanosis
  • Generalised duskiness in mild form
  • Blueness in nail-beds/lips in severe form
• Decrease in exercise tolerance
• Breathlessness/dizziness/fainting episodes

If the condition is not corrected in a timely manner, damage to the heart and/or lungs may be beyond repair and consequently limit the lifespan of your child.

Accurate diagnosis is necessary for the doctor to give appropriate treatment.

Antenatal (before a child is born) diagnosis is when a foetal cardiologist detects CHD during regular check-ups before the child is born. If this is the case, the plan of management and appropriate treatment can be fully discussed and agreed upon with the parents before labour.

After the child is born, when diagnosis is made soon after birth due to abnormalities detected in routine tests e.g.

• Abnormal (or low) oxygen saturation measurements
• Presence of heart murmurs during physical examination

Tests commonly used in the diagnosis of CHD include:

• Electrocardiogram (ECG)
• 2-D echocardiogram (ECHO)
• Cardiac catheterisation
• Cardiac magnetic resonance imaging (CMRI)

In some cases, CHD may be life-threatening and must be surgically corrected

• Hours after birth e.g. in total anomalous pulmonary venous drainage
• Within a few days e.g. in transposition of great arteries

In other cases, the operation can be carried out after a few months or years. In other instances, it is better to repair the defect(s) in stages , for example: putting in a temporary shunt to redirect the blood flow so that your child can grow bigger and stronger before carrying out a definitive procedure e.g. Tetralogy of Fallot.

The following are some of the common paediatric heart surgical procedures.

• The chest cavity and the heart need to be opened in order to repair the defect.
• This requires a "cardiopulmonary bypass (CPB)" machine during the surgery to oxygenate and circulate the blood without using the heart or lungs allowing the safe performance of the open heart surgery.

Examples of conditions requiring open heart surgery:

Septal Defects

• Atrial Septal Defect

• Ventricular Septal Defect

• Atrio-Ventricular Septal Defect

Defects causing obstruction to blood flow

• Pulmonary Stenosis

• Aortic Stenosis

• Tetralogy of Fallot

Defects involving the Great Arteries

• Transposition of Great Arteries

Surgery: Arterial Switch Operation

Other Complex Lesions

• Hypoplastic Left Heart Syndrome

Surgery: Norwood Stage I Surgery

For this surgery, the CPB machine is not used and the heart is visualised without having the heart opened.

Examples of conditions requiring closed heart surgery include:

• Patent Ductus Aeteriosus (PDA)

• Coarctation of aorta

• Blalock Taussig Shunt

• Your paediatric cardiologist will refer you and your child to a paediatric cardiac surgeon who will discuss the planned surgical procedure with you.
• Depending on the urgency of the surgery, the discussion will either take place in an outpatient clinic or in the ward.
• Once the date for surgery is fixed, your child will be admitted a day prior to the planned procedure for pre-operative preparation such as:
  • Taking blood for routine tests
  • Chest X-ray
  • ECG
• The tests rule out any active infection or any other minor conditions that were not detected in previous investigations.
• As a parent, you will need to prepare yourself psychologically. Discuss of any concerns that you may have with your child’s surgeon.
• Should you prefer, you can request for a tour of the paediatric intensive care unit to be arranged prior to surgery.

What happens during the surgery?

• You will be allowed to accompany your child into the area in the operating theatre where the anaesthetist will prepare your child to receive general anaesthesia.
• Your child will be injected with, or inhale an anaesthetic agent to put him/her to sleep.
• Once your child falls asleep, you will be asked to leave the operating theatre.
• The anaesthetist will then insert a breathing tube (endotracheal tube) and put in various drips such as the central venous catheter, arterial cannula, and intravenous cannula.
• The time taken for the surgery will depend on the complexity of the procedure. It could last from an hour to as long as 6 hours.
• Once the procedure is successfully performed, you will be notified by one of the healthcare professionals.
• The surgeon will usually speak to you after the operation.

The surgical team (paediatric cardiac surgeon and anaesthetist) will discuss the surgery at length with you. This includes the possible risks and benefits of the surgery.

If surgery has been recommended for your child, this means that the doctors have good reason to believe that the benefits of the surgical intervention outweigh its risks.

The major risks include:

• Risk to life
• Neurological abnormality
• Arrhythmia (irregular heartbeat) that may sometimes require insertion of a permanent pacemaker
• Abnormality of the kidney function that may require temporary dialysis or very rarely, permanent dialysis
• Bleeding during or after the surgery
• Infection of the wounds

As a parent, you will be well informed of the risks and benefits of the surgery in advance so that you can make a decision with the help of the doctors.

Prior to your child’s discharge, he/she should be:

• Pain free
• Walking/running around
• Eating and drinking well
• Having good bowel movements

• After discharge, your child will be required to see both the cardiologist and the surgeon for review.
• At the first review, which is within two weeks of the discharge, your child will be examined thoroughly including a wound review. His/her medications will also be reviewed and may be changed depending on how he/she is doing.
• For good cosmetic results, absorbable stitches are usually used for the large wounds. However, for the smaller wounds (e.g. the site where the chest drains were inserted after the surgery), non-absorbable sutures are used and these will be removed during the first review.
• Your child will receive follow-up reviews by a paediatric cardiologist at regular intervals (usually 2 weeks, 6 weeks, 3 months, 6 months, 12 months and annually after discharge from the hospital), and necessary investigations will be carried out during these appointments.

The surgical wound may get infected after discharge from the hospital.

You should contact the ward/doctors/nursing staff to make an appointment for an earlier review if you:

• Notice any ooze or redness from the surgical wound
• Have concerns regarding your child’s recovery at home

The review can be arranged as soon as possible so that you can be reassured, and any potential problems picked up well in advance.