Congenital Heart Defects (CHD): A Complete Guide

According to the American Cardiac Association studies, 9 out of every 1000 newborns have congenital heart defects.

Data obtained from the Global Burden of Disease study from 2017 revealed that congenital heart defect is more common in developing nations and less common in developed nations. Heart problems are typically present in 0.8 % to 1.2 % of live births worldwide.

Understanding CHD

Congenital is an adjective used to describe something that exists from birth. Therefore, congenital heart disease describes a heart abnormality, which is present from birth that interferes with how a heart normally functions.

It could manifest as a structural or functional anomaly in a baby's heart that could impair the body's overall blood flow.

Types of congenital heart defects

There are generally three different types of congenital heart defects:

Heart valve defects - These occur when a heart valve becomes too narrow (e.g., aortic coarctation) or closes (e.g., bicuspid aorta). This causes an inability of the heart to pump blood correctly. In certain cases, the valve cannot close completely, enabling the blood to flow backward (e.g., aortic regurgitation).

Heart wall defects - The left and right heart chambers are divided by a natural wall. A defect would affect the development of the wall, resulting in the mixing of pure and impure blood. It might also result in blood flowing back into the heart or accumulating in other parts of the body where it isn't supposed to. As a result, the heart would have to work harder, causing the blood pressure to rise.

Blood vessel defects - When this occurs, the blood vessels that transport blood to and from the heart may not operate effectively, resulting in a number of heart issues.

Common congenital heart defects

Atrial Septal Defect (ASD)
This condition may be described as "a hole in the heart" in simpler terms. This hole develops within the two upper chambers of the heart, known as the atria and would affect the flow of blood through the heart.
Atrioventricular Septal Defect
This condition where holes present between the left and ventricles of the heart due to a congenital defect. These holes are also referred to as atrioventricular canals.
Bicuspid aortic valve
Typically, an aortic valve would have three cusps. In certain cases, however, babies may be born with an underdeveloped or closed cusp. This would mean the aortic valve would only have two functional cusps, disrupting the normal blood flow.
Coarctation of the Aorta
In this condition, the main artery of the heart, the aorta becomes constricted or narrowed.
Congenital mitral valve anomalies
The valve between the left atrium and left ventricle of the heart is called the mitral valve (atrioventricular valve). Birth defects that affect the valve include a leaky mitral valve (mitral valve regurgitation) or a narrowing of the valve (mitral valve coarctation).
Double-outlet Right Ventricle
This condition is present from birth. The aorta normally links to the left ventricle (the heart chamber that pumps oxygenated blood to other parts of the body). In this condition, however, the aorta is misplaced and is instead linked to the right ventricle.
d-Transposition of the Great Arteries
This defect occurs when the aorta and main pulmonary artery trade places (transposed).
Ebstein Anomaly
This is a rare congenital heart disease where the heart valve does not develop correctly. The tricuspid heart valve's leaflets develop malformations and do not function well as a result. This may then cause blood to leak from the valve and flow backwards.
Eisenmenger syndrome
This congenital defect results in abnormal blood flow to the heart and lungs. It causes the blood vessels in the lungs to narrow and stiffen, causing the pressure in the arteries of the lungs to rise.
Hypoplastic Left Heart Syndrome
This heart defect is quite complicated as it includes a number of defects of the heart's left chambers. The aorta and left ventricle are underdeveloped in this condition and the septum is unable to fully mature and close. Therefore, the blood is not pumped to other parts of the body in sufficient amounts. The condition could be fatal if it is not treated immediately
Interrupted Aortic Arch
Interrupted aortic arch occurs when a portion of an infant's aorta is missing. This condition necessitates immediate surgery following birth due to the heart's inability to deliver blood from the aorta to other parts of the body.
Pulmonary Atresia
This is a condition where the pulmonary valve is absent. This leads to difficulties in the blood reaching the lungs and receiving oxygen for the body.
Pulmonary valve stenosis
The function of the pulmonary valve is to regulate the blood flow from the right side of the heart to the lungs. A defect would cause the valve to be narrower than usual and would make the right side of the heart work harder.
Single Ventricle
This heart defect is severe and could be fatal within the few weeks following birth. A single ventricle is a defect in which only one ventricle (lower heart chamber) develops normally.
Tetralogy of Fallot
This is a rare condition, which consists of a number of defects, including:
- The presence of a hole between both ventricles
- The narrowing of the pulmonary valve
- The thickening of the muscles of the right ventricle
- The incorrect positioning of the aorta
Total Anomalous Pulmonary Venous Return (TAPVR)
Oxygenated blood is transported to the heart from the lungs through four veins. TAPVR arises when the four veins are incorrectly linked, allowing blood to leak or enter the wrong chambers.
Tricuspid Atresia
Heart-lung-heart-body is the heart's typical blood cycle. Infants who suffer from tricuspid atresia lack the valve that regulates this flow. As a result, the blood would not flow normally.
Truncus Arteriosus
The condition develops when the two main arteries do not develop correctly and are instead fused into a single vessel.
Ventricular Septal Defect (VSD)
The wall separating a heart's two lower chambers is called the ventricular septum. When this wall develops a hole, more blood is forced into the right ventricle, resulting in VSD. This would then lead to congestion in the lungs.
Vascular rings
This is a disorder where the coronary arteries, which provide oxygen-rich blood to the heart, become inflamed.
Long QT syndrome (LQTS)
LQTS is a condition that affects the heart rhythm, causing rapid, erratic heartbeats. The condition can be fatal.
Partial anomalous pulmonary venous return (PAPVR)
This heart defect causes the incorrect attachment of the pulmonary (lung) blood vessels in the heart.
Patent ductus arteriosus (PDA)
This condition develops due to an unclosed hole in the aorta. Every newborn has a ductus arteriosus at birth, but it closes after a few days. It might, however, stay open in some situations involving premature births. Closure may then be required, necessitating medication or catheterisation.
Patent foramen ovale
This is a condition where a hole in the heart does not close following birth. A foramen ovale is present in the right and left top chambers as a baby grows in the womb. However, a patent foramen ovale develops when it does not close as it normally should.
Wolff-Parkinson-White (WPW) syndrome
This condition causes tachycardia (fast heart rate). This is caused by an additional channelling pathway between the upper and lower heart chambers.

Causes

The heart of a foetus develops during the initial eight weeks of pregnancy. If the foetus has a defect, it typically manifests itself at this critical period.

There are several causes of congenital heart defects in infants.

One cause is the alterations in the chromosomes and genes of the infant. This may be hereditary and may be inherited from either parent. The genetic condition that is most well-known and can result in a defect is Down's syndrome. Turner and Noonan's syndrome are other genetic conditions that are associated with congenital heart defects.

Risk factors

Babies may develop heart defects if the mother uses certain medications.

For instance, the use of benzodiazepines or ibuprofen is associated with a higher risk of a baby being born with a heart abnormality.

Additionally, contracting the flu during the first trimester may increase the risk of congenital heart abnormalities. Therefore, it is advised that all women get vaccinated before getting pregnant.

Signs and symptoms

Symptoms in adults

Fast breathing
Rapid pulse rate
Fatigue
Shortness of breath when exercising
Fainting when exercising
Swelling in hands, legs, feet, ankles, abdomen or other body parts
Blue discolouration of the nails, lips, etc.

Symptoms in children

It is possible for newborns with heart problems to have blue skin, lips, fingers and toes. They might struggle to breathe or feed, breathe quickly, have an irregular heartbeat or have a very low birth weight.

Congenital heart symptoms can sometimes go unnoticed until a few years after birth. However, once they occur, you may experience symptoms such as excessive exhaustion, dizziness, or swelling in your hands, feet, ankles, or legs.

Diagnosis

Foetal echocardiography, which produces ultrasound images of the developing baby's heart, can be used to diagnose some congenital heart defects during pregnancy. Additionally, your doctor may also perform a few physical examinations.

Here are some tests that might be used in the diagnosis of a heart defect in adults or newborns:

Electrocardiogram (ECG)/Stress test - it is used for the diagnosis of clogged arteries and irregular heartbeats and is performed while using a bike or a treadmill.
Chest X-Ray - This examination reveals any abnormalities in the heart's and lungs' size and shape.
Pulse oximetry - This test is used to determine the amount of oxygen present in the blood and is performed by connecting a finger to a sensor.
Echocardiogram - This test assesses the functionality of the chambers and valves of the heart in pumping blood by producing ultrasound images of the heart.
Transoesophageal echocardiogram - This test produced more detailed images of the heart. It involves inserting a flexible tube with a transducer down the throat and into the oesophagus (the tube that connects the mouth to the stomach) and is performed under sedation.
Cardiac CT scan and MRI - These tests are performed to produce images of the chest and heart so any defects can be detected.
Cardiac catheterisation - This is done to measure the heart's blood pressure and blood flow. A dye is introduced via a catheter to help reveal any blood vessel obstructions.

Treatment options

The advanced medical technology and high standards of medical science currently available make it possible to correct most congenital cardiac problems, if not all of them, if discovered early.

The type of treatment is determined by how severe the defect is. Among the treatment options available are:

Medicines
Cardiac catheterisation
Open heart surgery
Heart transplant
Implantable heart devices

Life expectancy for CHD

The survival rate of newborns with congenital cardiac disease depends on the severity of the defect, when the defect was discovered and how the defect is treated.

The Centers for Disease Control and Prevention reported that 97% of infants born with non-critical heart problems will survive to be a year old, and 95% will survive up to the age of 18.

It is predicted that 75% of infants with critical heart conditions will survive their first year and 69% will do so until they are 18 years old.

Prevention

Given that the exact causes of congenital heart defects are unknown, prevention may not be possible. However, here are some measures you can take to help lower the risk:

Visit your doctor for prenatal care on a regular basis while pregnant
Take supplements that contain folic acid
Avoid drinking alcohol or smoking (avoid inhaling second-hand smoke too)
Get vaccinated to avoid contracting a rubella infection (German measles)
Look after your blood sugar level
Manage chronic medical conditions e.g., phenylketonuria
Avoid inhaling harmful substances e.g., strong-smelling paint or cleaning products
Consult your doctor or pharmacist before taking any medications

Visit your nearest Gleneagles Hospital to learn more about our Cardiology Services

References:

Congenital heart defects in children. Available at https://www.mayoclinic.org/diseases-conditions/congenital-heart-defects-children/symptoms-causes/syc-20350074#: [Accessed on 11 May 2022]
Wu, Wei Liang, Incidence and mortality trend of congenital heart disease at the global, regional, and national level, 1990–2017, Available at https://journals.lww.com/md-journal/fulltext/2020/06050/incidence_and_mortality_trend_of_congenital_heart.68.aspx [Accessed 16 February 2022]
Types - Congenital heart disease, Available at https://www.nhs.uk/conditions/congenital-heart-disease/types/ [Accessed 16 February 2022]
About Congenital Heart Defects, Available at https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects [Accessed 16 February 2022]
Congenital Heart Disease, Available at https://www.stanfordchildrens.org/en/topic/default?id=congenital-heart-disease-90-P02346 [Accessed 16 February 2022]
Congenital heart defects in children, Available at https://www.mayoclinic.org/diseases-conditions/congenital-heart-defects-children/symptoms-causes/syc-20350074 [Accessed 16 February 2022]

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