All about paediatric congenital heart disease

Paediatric congenital heart disease (CHD) refers to a range of heart defects that are present at birth. They affect the structure and function of a child's heart. These defects can vary from mild conditions that may resolve over time to severe abnormalities requiring immediate medical intervention.

Here to provide an in-depth look at this condition is leading paediatric cardiology consultant Dr Florian Moenkemeyer.

What is paediatric congenital heart disease?

Understanding congenital heart defects

Congenital means present at birth. Congenital heart disease describes a problem with the heart's structure and function due to abnormal heart development that happens before birth. These defects can affect the heart’s walls, valves, blood vessels, or a combination of these structures.

The normal heart

The heart is a pump and consists of four chambers. There are two: Collecting chambers and two pumping chambers.

The right collecting chamber takes the used blood from the body and forwards it into the right pumping chamber, which then pumps the blood into the lungs to take up oxygen. From the lungs the now oxygenated blood flows back to the left collecting chamber and into the left pumping chamber, from where it is pumped back into the body so the organs can use the oxygen. There is usually a solid wall of tissue between the walls of the upper 2 and the lower 2 chambers.

The heart generates an electric impulse that travels through the muscle to tell them how to squeeze in an organised fashion.

Congenital heart defects can occur anywhere in the heart but there are some common sites and patterns of abnormality.

Common heart defects requiring intervention

Patent Ductus Arteriosus (PDA): The ductus arteriosus is a vessel that creates a bypass to the lungs prior to birth as the oxygen at the time comes from the mother’s placenta and the blood flow in the foetus is different to that of the newborn.  This vessel usually closes after birth, but if it remains open it is called a patent ductus arteriosus and might increase the blood flow to the lungs. This can result in elaborate and harder breathing which requires more energy, that is not available to grow and thrive. An echocardiogram will allow to make the diagnosis and help to decide if a closure should be performed. In most cases this can be done with a little device, that is deployed in the vessel via a small catheter entered through the large groin vessels and avoiding surgery. Some cases will require a surgeon, who will tie the vessel off after opening the chest from the side.

Atrial Septal Defect (ASD): The term ASD describes a hole in the wall between the collecting chambers of the heart. Whilst all humans have a small hole in this wall in utero, which usually closes after birth an ASD describes an incomplete formation of the wall. Not every ASD requires closure, but larger ones might over time result in too much blood flow into the lungs resulting in compromise of the cardiovascular performance. In many cases the ASD can be closed with a so-called interventional procedure. In this “keyhole” intervention a small device can be advanced via a larger groin vessel into the heart and then expanded to close the hole between the collecting chambers. If this is not possible the defect can be surgically closed.

Ventricular Septal Defect (VSD): A ventricular septal defect is a hole in the wall that separates the lower right and left heart pumping chambers (ventricles).

In patients with VSD, oxygen-rich blood passes from the left ventricle and mixes with oxygen-poor blood in the right ventricle. The larger the hole, the more symptoms it can cause. If there is significant flow of blood across the hole some infants may develop difficulty with growth and breathing. Symptoms due to the VSDs may be able to be managed with medication and high calorie feeding regimes. Many VSDs will become smaller on their own and even close spontaneously over time.

If an infant has significant difficulties with growth or breathing, despite medical therapy, then surgical closure can be performed with excellent results.  In some instances, the defect can be amenable to a catheter or “keyhole” based procedure. The need for surgical or interventional closure is based on the type and size of defect as well as clinical symptoms seen in the baby or child.

Atrioventricular Septal Defect (AVSD): This is a common complex heart problem in people with Downs síndrome, but it can also be present without this genetic diagnosis. Essentially, it results in a deficiency to develop parts of the wall between the collecting chambers, pumping chambers and also affecting the main heart valves on both sides of the heart. In the majority of cases this requires a surgery in infancy to close the holes and improve the valve function.

Tetralogy of fallot (TOF): This is a complex structural abnormality involving the right side of the heart with four specific features. During development the main body artery is shifted to the right causing a hole in the heart (VSD), narrowing of the lung artery and thickening of the right pump muscle. Children with Tetralogy of Fallot require surgical intervention typically between 3 and 6 months of age. For most, a full repair surgery is performed as one operation. But in rare instances, a child may require a series of operations.

• Coarctation of the aorta (CoA): A narrowing of the aorta in the region of the ductus arteriosus (PDA), which bypasses the lung during foetal development. After birth the normal physiological adaptation processes result in closure of the PDA, which can lead to severe narrowing of the aorta and the left pumping chamber will have to work very hard to overcome this narrowing. Once identified the Newborn can receive a drug to keep the PDA open until safe surgery can be undertaken with excellent results. Frequently the narrowing can be associated with underdevelopment of longer segments of the aorta, abnormalities and a small aortic valve and even underdevelopment of structures of the left pumping chamber.

• Transposition of the great arteries (TGA): In TGA the 2 main arteries to the lungs and to the body are incorrectly connected to the pumping chambers resulting in a so-called parallel circulation. In some newborn babies this requires an urgent intervention directly after birth. Fortunately, we are nowadays able to diagnose this condition in the majority of cases in the routine antenatal scans and can intervene early after birth if required. Once stable circulation is achieved surgery can take place in the neonatal age. The surgeons will ‘switch’ the two arteries into the correct position usually with excellent results and a very good prognosis for the baby.

What causes congenital heart disease?

Congenital heart defects and their exact causes are unknown. However, certain factors may increase the risk of a child being born with a heart defect:

• Genetic factors: Family history of congenital heart defects or genetic conditions. An example of this is Downs Syndrome (Trisomy 21) where up-to 50% of patients have some form of heart disease.
• Environmental factors: Maternal illnesses (e.g., rubella), certain medications, alcohol, or drug use during pregnancy.
• Chromosomal abnormalities: Changes in the number or structure of chromosomes.

What are the symptoms of paediatric congenital heart disease?

Symptoms of congenital heart disease in children can vary widely depending on the type and severity of the defect. Common signs and symptoms include:

• Cyanosis: A bluish tint to the skin, lips, and fingernails due to low oxygen levels in the blood.
• Rapid breathing: Difficulty breathing or breathlessness, particularly during feeding or physical activity.
• Poor feeding: Difficulty in feeding or poor weight gain in infants.
• Fatigue: Excessive tiredness or lethargy, especially during physical exertion.
• Heart murmurs: Unusual sounds heard during a heartbeat, often detected during routine check-ups.

How is congenital heart disease diagnosed?

Often, congenital heart disease diagnosed either during pregnancy or shortly after birth. Diagnostic methods include:

Echocardiogram: An echocardiogram is a special test that takes pictures of the heart using sound waves. During the test, a small device is placed on the chest, and it sends out harmless sound waves that bounce off the heart. To get better pictures a special gel is used between the probe and the chest. The sound waves create pictures of the heart's parts, like its chambers, valves, and blood vessels in real time creating moving images. This allows the Cardiologist to investigate how the heart is working and how blood is moving inside. It can show how the heart is built or how its valves work. Nowadays a majority of congenital heart abnormalities is already diagnosed in pregnancy once the routine ultrasound scan raises a suspicion followed by a foetal echocardiogram.

12 lead ECG (Electrocardiogram): This a valuable investigation to look at the electrical pathways of the heart. The test involves placing 12 stickers or electrodes on the chest and analysing how the electrical impulses spread through the heart.

​

Heart monitor: This may be fitted to look at the heart rate and rhythm over a longer period. This way it might be possible to catch intermittent and short-lived episodes and initiate treatment if required.

Exercise test: If there are exercise associated symptoms, a treadmill or bike exercise test may be undertaken, with real-time ECG monitoring to assess the heart under physical stress. Sometimes the doctors might decide to measure the contents of the air breathing in and out during the exercise test to gather even more information about the body’s ability to perform and use it’s energy. This is done by wearing a mask and breathing into a machine during the exercise test.

What treatment options are available for congenital heart disease?

Treatment for congenital heart disease depends on the specific defect and its severity. Options include:

Non-surgical treatments

• Medications: To help the heart work more efficiently, prevent blood clots, or manage symptoms.
• Cardiac catheterisation: Procedures performed using a catheter to repair certain heart defects without the need for open-heart surgery.

Surgical treatments

• Open-heart surgery: To repair or correct structural defects within the heart. For most operations the heart needs to be stopped for the procedure to allow access for the surgeons to the structures inside the heart. A heart and lung machine (Cardiopulmonary bypass, CPB) takes over the function of the lung and heart temporarily until the surgeons have finished the operation. Less frequently certain surgical interventions can be done without the need for cardiopulmonary bypass.
• Heart transplant: In cases of severe heart defects that cannot be repaired.

Long-term management

• Regular follow-ups: Monitoring by a paediatric cardiologist to manage and assess the child’s heart condition.
• Lifestyle modifications: Encouraging a healthy diet, regular exercise, and avoiding smoking.

Cardiac conditions not affecting the structure of the heart

A smaller group of heart problems in children develop after birth and are due to problems with the heart muscle itself, acquired infection in childhood or due to electrical irregularities that interfere with the way the heart contracts, as it pumps blood around the body.

Cardiomyopathies: These are abnormalities of the structure and function of the heart muscle itself. Fortunately they are quite rare, but they can run in families and are inherited. For some of them the genetic abnormalities have been identified, but in the majority of cases the cause is unknown.

Sometimes cardiomyopathies can result from factors haveing a negative influence on the heart muscle like infections or certain drugs and enviromental factors.

Rhythm abnormalities: The heart produces an electrical impulse, that travels through it and tells all the muscle cells in which order to contract. Sometimes short circuits can develop that result in much faster heart rates than normal. Fortunately, there are several protective mechanisms in the heart to protect the pumping chambers form beating so excessively fast, that the circulation fails. However, it is not healthy to keep the heart working faster than normal for a long period of time. Once identified, treatment can be offered to interrupt the fast heart rate and if it happens frequently medication can prevent further episodes. For many of these electrical disturbances, a test to assess the heart’s electrical system can be performed once the patient is big enough to allow this safely. Small catheters are used to enter the heart through the groin vessels and the area of abnormal electricity is identified. The short circuit is then interrupted with a little burn or freeze of the tissue. 

Abnormal slow heart rates are very uncommon in children. Very rarely the electrical pathway from the heart’s collecting chambers to the heart’s pumping chambers can be interrupted, which is called a heart block. This can be present at birth due to a rare maternal disease with antibodies, that can travel through the placenta and damage the foetus’ electrical pathway. Sometimes certain abnormalities of the heart structure or certain infections can result in this interruption. A pacemaker can be implanted to overcome this interrupted pathway.

Pulmonary hypertension: This is when the blood pressure in the vessels that go to the lungs is too high. It can make the heart work harder and even cause the heart to struggle (a situation called heart failure).

Careful, ongoing review with a paediatric cardiologist and medication can help make a clear diagnosis and support the management needed to help the baby or child reach his or her full potential.

Common referrals for a cardiology review in childhood

Heart murmurs: Many children are referred for investigations due to a murmur. A murmur is a noise that can be heard with a stethoscope and is created by turbulent flow inside the heart. Most of the time this is not representing a problem of the heart and is called an innocent murmur. However, in some cases it can be a sign of a narrowing of one of the blood-flow pathways or a hole between the chambers of the heart. The sound that can be heard is a bit like a narrowing of a river where you can see the turbulent white-water and hear more noise.

Innocent murmurs are very common in a baby or child and are not due to congenital heart disease. These murmurs are usually generated as a consequence of the blood flowing, at speed, around tight corners and bends in a relatively smaller heart (as compared to an adult). Innocent murmurs become more apparent during times when the heart works a little harder (producing more turbulence) such as during fever or exertion or the child is anxious or upset.

When to get checked: If your family doctor (GP) or hospital doctor isn't sure whether your child's murmur is innocent, or if your child shows concerning clinical symptoms, they might send you to a heart specialist called a cardiologist. These signs could include getting tired quickly, breathing difficulties, bluish skin, or feeling dizzy or fainting. The cardiologist will be able to arrange tests to find out if a murmur could be something serious.

Chest pain: Chest pain in children is very common, most often innocent, and not usually originating from the heart.  However, if your child has severe chest pain or chest pain that is accompanied with difficult breathing, a fever, sweating, a very high heart rate or dizziness you should promptly consult with your doctor.

There are many other organs and parts, that can be responsible for pain in the chest apart from the heart. Most commonly the chest bones, it’s muscles or even problems with the food pipe are responsible for chest pain in children.

Musculoskeletal pain: Is pain arising from the ribs or chest muscles? It’s the most common cause of chest pain or chest discomfort in children and teenagers. This type of pain often has no clear cause and usually reflects changes during growth.

Musculoskeletal type pain is often ‘sharp’ and short. This type of pain is often made worse by breathing in and out – or pressing the area reported. Cardiac pain is usually different in character. It is often a dull or heavy ache that is worse during or after exercise.

Heart related chest pain: True cardiac chest pain is rare in a teenager or child. A detailed clinical history of the nature, type and frequency of the pain can often help a paediatric cardiologist work out whether the pain has an underlying cardiac cause.

The presence of other symptoms such as palpitations (an irregular or fast heart rate) or a history of fainting or collapse would prompt more detailed investigation and assessment.

A positive family history of cardiac problems or history of early or unexplained death in the family would also raise caution. A paediatric cardiologist will undertake formal paediatric cardiac assessment which will include clinical examination and detailed heart echocardiography (a heart scan) to best assess the structure and function of the heart.

Palpitations: Palpitations in children usually aren't a sign of a health problem, and most children who have them will have a normal heart. Palpitations is an umbrella term describing many symptoms with the term meaning different things to different people. Children have slender chest walls and can often become aware of their heart beating. The heart beating fast and forcefully can be perceived to be uncomfortable. Most often this is innocent and not related to a problem with the heart rhythm.

Some children can have extra cardiac beats or an irregular heart rhythm (more commonly tachycardia (fast) or less common bradycardia (slow) at times these may feel uncomfortable. In the vast majority of cases even pathological rhythm abnormalities are not life threatening as the heart has safety mechanisms preventing the heart to beat extremely fast or chaotic. 

A detailed clinical history of the nature, type and frequency of the palpitations, associated symptoms and family history can often help a paediatric cardiologist stratify the importance of any rhythm problem if present. A history of syncope or collapse would prompt more detailed investigation and assessment.

A positive family history of cardiac problems or history of early unexplained death would raise caution and might point to rather rare but more dangerous inherited heart rhythm abnormalities. Formal paediatric cardiac assessment will include top to toe clinical examination and detailed echocardiography to best assess the structure and function of the heart.

If your child requires an expert in paediatric heart disease, arrange a consultation via Dr Moenkemeyer’s Top Doctors profile.