Congenital Heart Disease in Children

Congenital means inborn or existing at birth.

Congenital heart disease or defect (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.

Terminology

The list below describes some terms commonly used in CHD:

• Stenosis - narrowing
• Atresia - absence of
• Atrium and Ventricle - there are 4 chambers in the heart; both right and left having 2 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 - act as one way valve
• Tricuspid valve - this is the opening between the top and bottom chambers in the right side of the heart - act 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 - act as one way valve
• Pulmonary valve - the valve in the opening the connects the right side of the heart to the vessels that deliver the used, oxygen depleted blood to the lungs - act 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:

1. Obstruction to blood flow

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

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

2. Left to right shunt

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-blue blood) from the rest of the body and delivers it to the lungs. The left side of the heart is responsible for oxygen-rich blood - red blood from the lungs to send 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 "extra volume" of blood. When this happens, it results in too much blood flowing into the lungs.

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

3. Right to left shunts

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” 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.

• Tetralogy of Fallot (TOF)
  • TOF has 4 abnormalities which are:
    • 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

4. Complex cyanotic defects

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 once.

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

• Antenatal (before a child is born) diagnosis when a fetal cardiologist detects CHD during regular check-ups before the child is born.
  • If this is the case, plan of management and appropriate treatment can be fully discussed and planned 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
• Other defects may only be diagnosed later on in the child's life.

Common tests used for diagnosis of CHD:

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

How does it affect my child’s health?

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 could get beyond repair and consequently limit the life span of your child.

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, whilst in at times it is to repair the defect(s) in stages e.g.

• 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

Surgery for Paediatric Congenital Heart Diseases

• Overview
• How do I prepare my child for surgery?
• What happens during the surgery?
• What are the potential risk or complications?
• What happens after the surgery?
• Home care
• When should I call the doctor?

1. Overview

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

1.1. Open heart surgery

• 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:

1.1.1. Septal Defects

• Atrial Septal Defect

  

• Ventricular Septal Defect

  

• Atrio-Ventricular Septal Defect

  

1.1.2. Defects Causing Obstruction to blood flow

• Pulmonary Stenosis

  

• Aortic Stenosis

  

  

• Tetralogy of Fallot

  

1.1.3. Defects involving the Great Arteries

• Transposition of Great Arteries Surgery: Arterial Switch Operation

  

1.1.4. Other Complex Lesions

• Hypoplastic Left Heart Syndrome Surgery : Norwood Stage I Surgery

  

  

1.2. Closed heart surgery

• In this type of surgery the CPB machine is not used and the heart is visualised without having the heart opened.

Examples of condition for Closed Heart Surgery:

• Patent Ductus Aeteriosus (PDA)

  

• Coarctation of aorta

  

• Blalock Taussig Shunt

  

2. How do I prepare my child for surgery

• Your paediatric cardiologist will refer you and your child to a paediatric cardiac surgeon who will discuss with you the planned surgical procedure.
• Depending on the urgency of the surgery, the discussion will either take place in an out-patient 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 would need to prepare yourself psychologically. Discuss with your child’s surgeon of any concerns that you may have.
• Should you prefer, you can request for a tour of the paediatrics intensive care unit to be arranged prior to surgery.

2.1.What happens during the surgery?

• You will be allowed to accompany your child into the area in the operating theatre where the anaesthetic doctor will prepare your child to receive general anaesthesia.
• You child will be injected with or inhale in 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 – central venous cathether, arterial cannula, intravenous cannula.
• The time taken for the surgery would 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 health professionals.
• The surgeon will usually speak to you after the operation.

2.2. What are the potential risks or complications?

• The surgical team (paediatric cardiac surgeon and anaesthetist) will discuss the surgery in 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 and 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.

2.3. What happens after the surgery?

• Your child will be transferred to the paediatric intensive care unit (PICU) after the operation.
• There will be many tubes connected to your child for various purposes, so do not be alarmed.
• Your child will usually be under deep sedation (asleep) usually for up to 24 hours or longer after surgery, depending on the complexity of the surgery and the age of the child.
• It is important to cooperate with the paediatric ICU staff who are well trained, caring and friendly.
• Usually a nurse will be assigned to look after your child solely during his/her stay in ICU.
• As every patient is different, the staff will discuss your child’s hourly/daily progress and treatment plans.
• Your child may be kept in the ICU for about 2 days depending on his/her recovery progress.
• When your child is stable, he/she will then be transferred to a high dependency unit (HDU) for further close monitoring for another 1-2 days until he/she is stable enough to be transferred to the general paediatric ward.
• At this stage, most of the tubes and drips will be removed from your child’s body.
• Most of the recovery will be taken place in the general ward:
  • He/she will be encouraged to move about and will be guided by a physiotherapist.
  • Depending on the recovery progress, you can expect a period of 5-7 days in the general ward before your child is discharged from the hospital.
• A thorough physical examination and various investigations will be carried out prior to discharge. These tests are:
  • Blood Tests
  • ECG
  • Chest X-ray
  • 2-D ECHO
• During your child’s recovery period, the parents are encouraged to get as much rest as possible. Once the child is discharged from the hospital, you will be solely looking after child at home. This can be physically demanding and mentally challenging.

2.4. Home care

• 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 and his/her medications will be reviewed and may be changed depending of 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.

3. When should you call the doctor?

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

• Pain free
• Walking/running around
• Eating and drinking well
• Good Bowel Movements.

However, the surgical wound may get infected after discharge from the hospital.

You should contact the ward/doctors/nursing staffs 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.