Surgical Procedures in Congenital Heart Disease

What Are Congenital Heart Defects?

Congenital heart diseases are a group of diseases that are characterized by defects associated with the structure and function of the heart and are present from birth. These diseases can be detected at any phase of life in an individual- before birth, at birth, or anytime throughout life. The various types of defects include -

• Septal Defects - Commonly referred to as 'hole in the heart', these defects are associated with openings between the right and left sections of the heart.

• Heart Valve Defects - Structural and functional defects in the heart valves characterize these defects. Heart valves are muscular structures present in the heart and help in efficient blood flow in the right direction throughout the heart. They are four in number: mitral, tricuspid, pulmonary, and aortic valves.

• Defects Associated With the Blood Vessels Supplying the Heart - The heart receives inefficient oxygen and blood when defects are associated with the blood vessels supplying the heart.

Such diseases constitute a very common birth defect, with 1 in every 100 live births. There are numerous types of congenital heart diseases, and the treatment also varies based on the type of congenital heart disease.

What Are the Causes of Congenital Heart Defects?

Congenital heart defects usually occur when certain factors impede the normal development of the fetal heart (within the first ten weeks of pregnancy). The various causes of congenital heart defects include -

• Maternal diabetes.

• Alcohol consumption during pregnancy.

• Rubella infection (also known as german measles) during the first ten weeks of pregnancy.

• Smoking during pregnancy.

• Genetic conditions.

• Consumption of certain medications (for example, Isotretinoin, Diazepam, Retinoids, etc.).

• Use of recreational drugs during pregnancy.

• Exposure to second-hand smoke during pregnancy.

What Are the Various Types of Congenital Heart Defects?

There are several types of congenital heart diseases. They include the following-

1. Acynotic Congenital Heart Defects:

This term is used to refer to heart defects that do not hamper oxygen supply. Such defects are usually of the following types:

• Hole in the Heart - This defect is characterized by a hole in the muscular walls of the heart. For example - atrial septal defect, ventricular septal defect, and patent ductus arteriosus.

• Defects Associated With the Aorta - These defects lead to abnormal blood flow in the entire body. For example- aorta coarctation, transposition of the great vessels, etc.

2. Cyanotic Congenital Heart Defects:

Such heart defects lead to inadequate oxygen supply. They include the following defects:

• Left Heart Obstructive Lesions - Lead to decreased systemic blood flow (blood flow in the entire body). For example, hypoplastic left heart syndrome, and interrupted aortic arch.

• Right Heart Obstructive Lesions - Lead to reduced pulmonary blood flow (between the lungs and heart). For example, tetralogy of Fallot, pulmonary atresia, and tricuspid atresia.

• Mixing Lesions - There is a mixing between the pulmonary and systemic blood flow. For example truncus arteriosus.

What Symptoms Are Associated With Congenital Heart Defects?

Symptoms associated with congenital heart defects can vary and be seen at birth or anytime after birth. The various symptoms include -

• Shortness of breath.

• Heart murmurs (heard during physical examination).

• Bluish skin discoloration due to inadequate oxygen delivery in the body.

• Weak pulse.

• Fatigue or unexplained tiredness.

• Excessive sleepiness.

• Irregular heartbeats.

How Are Congenital Heart Defects Diagnosed?

Numerous tests can be employed to determine congenital heart defects in newborns, adults, or children. They include -

Prior Birth -

• Fetal Echocardiogram: Also known as fetal echo, it is a diagnostic test performed between weeks 18 and 22 of pregnancy. Ranging from half an hour to two hours, this procedure involves using sound waves to generate visuals of the heart. These visuals help in detecting structural abnormalities in the fetal heart.

After Birth-

• Pulse Oximeter: It is a device attached to the newborn's fingers or toes and helps measure oxygen saturation (the amount of oxygen in the infant's body). If the oxygen saturation is less, it warrants further testing.

• Physical Examination: With the help of a stethoscope, a physician will assess for abnormal heart sounds to identify heart malfunction. The physician will also look for signs of heart failure. A few signs of heart failure are-

• Swelling in the lower limbs, especially at the ankles.

• Crackles in the lungs due to fluid accumulation.

• Fluid accumulation in the neck veins, making them appear engorged.

• Chest X-Ray: It is a diagnostic test that creates a black-and-white image of the lungs, heart, blood vessels, and airways using special beams of radiation called the x-rays.

• Electrocardiogram: Also referred to as EKG and ECG, it is used to assess different heart conditions by recording the heart's electrical impulses with the help of electrodes.

• Echocardiogram: Also known as ECHO, it is a test that helps examine the heart's irregularities and associated structures with the help of ultrasound.

• Cardiac Catheterization: Also known as a traditional angiogram, it has been the gold standard test for assessing the health of a human heart. It is an invasive procedure that involves passing a thin, flexible tube (called a catheter) into the blood vessels (arteries).

• Cardiac Magnetic Resonance Imaging (MRI): With the help of magnetic and radio waves, cardiac magnetic resonance imaging (also known as cardiac- MRI), sectional images of the heart and its associated structures are generated.

How Are Congenital Heart Defects Treated?

The treatment for congenital heart defects varies and is based on the following factors-

• The age of the patient.

• Symptoms elicited.

• The severity of the condition.

• The number of heart defects.

• The type of heart defect.

The treatment for congenital heart defects is often an amalgamation of the following -

• Medications

• Open heart surgeries.

• Implantable heart or cardiac devices.

• Cardiac catheterization.

• Heart transplant (in rare cases).

What Are the Various Surgical Procedures Involved in Treating Congenital Heart Disease?

Several surgical procedures can be carried out to treat congenital heart disease, depending on the type of defect and the patient's age. They include -

Patent Ductus Arteriosus Ligation:

• Patent ductus arteriosus is a congenital heart defect characterized by the incomplete closure of the ductus arteriosus.

• The ductus arteriosus refers to a blood vessel that helps the fetus breathe. After birth, the lungs help to breathe, and the ductus arteriosus is not required. Hence, it closes.

• This disease is more common in premature babies and leads to abnormal blood flow in the heart and, subsequently, in the body.

• In most patients, the ductus arteriosus closes by itself, but if it does not, it must be closed surgically by ligating it.

• Ligation involves bringing the parts or ends of ductus arteriosus and tying them.

Coarctation of the Aorta Repair:

• Coarctation of the aorta is a defect that accounts for at least five percent of all congenital heart defects and is characterized by a very constricted and narrow section in the aorta, giving it an hourglass appearance.

• The aorta is an essential blood vessel in the body and is responsible for supplying blood and oxygen to the entire body.

• There are several ways of treating this defect. The first one includes widening the cross-section of the aorta with the help of a synthetic patch, called gore-tex.

• The second method includes surgically removing the constricted portion of the aorta and tying the normal-free ends together. This type of surgery is usually done in children.

• The fourth method involves bypassing the narrow portion of the aorta. This is done by surgically placing a tube at the wider ends of the aorta. By doing so, blood flows via the tube and bypasses the constricted part of the aorta.

Atrial Septal Defect Repair:

• An atrial septal defect is a type of congenital heart disease in which a hole is present in the atrial septum of the heart.

• The atrial septum is a muscular wall that divides the heart's upper chambers into right and left. Structural abnormalities during the development of the septum can lead to an atrial septal defect (ASD).

• An atrial septal defect creates a shunt between the heart's right and left upper chambers, leading to blood flow from left to right, resulting in less oxygen delivery in the body.

• Smaller defects having a size of fewer than five millimeters usually do not cause problems, and such defects are most often found later in life.

• One method of closing the defect is by surgically sewing it with the help of stitches.

• The method includes the hole without extensive open heart surgery. This method involves the insertion of two smaller umbrella-shaped devices on either side of the defect. These devices are attached, thereby closing the defect.

Ventricular Septal Defect Repair:

• Ventricular septal defect, often referred to as VSD, is a congenital heart defect with a hole in the ventricular septum.

• The ventricular septum is a muscular wall that divides the left and right ventricles (lower heart chambers).

• This defect results in the mixing of oxygenated blood with deoxygenated blood.

• Usually, these defects close without intervention when the baby is a year old.

• Surgical intervention is required when these defects fail to close on their own. An open heart surgery is performed to close such defects.

Tetralogy of Fallot Repair:

• It is a type of congenital heart disease that leads to the baby's cyanosis and comprises four types of congenital defects. They include-

• Ventricular septal defect.

• Right ventricular hypertrophy (thickening of the right ventricular wall).

• Over-riding or misplaced aorta (aorta is positioned over the ventricular septal defect instead of coming out from the left ventricle).

• Pulmonary stenosis.

• Occurring equally in both males and females, it is the most common type of cyanotic heart defect.

• To treat this disease, open heart surgery should be performed between the ages of 6 months to 2 years.

Transposition of the Great Vessels Repair:

• Transposition of the great vessels is a congenital heart disease in which the positions of the great vessels interchange.

• The aorta and pulmonary artery are referred to as the great vessels. Shortly after leaving the heart, the aorta gives off two offshoots called the coronary arteries.

• The consequence of the transposition of the great vessels is that the oxygen cannot be delivered to the body adequately. Unless treated quickly, the infant is unlikely to survive.

• Transposition of the great vessels (TGA) accounts for three percent of all congenital heart diseases and affects males more than females (3:1)

• This heart disease can only be treated via surgical approaches.

• The first method is the arterial switch operation (ASO), in which the great vessels are surgically switched to their correct anatomical positions.

• The second method is known as balloon atrial septosomy. This procedure is performed immediately once the baby is born with this defect to increase the oxygen saturation in the blood and is done by enlarging the foramen ovale (a natural hole between two collecting chambers of the heart). This surgery is not a permanent solution and helps buy time until the infant is ready for major heart surgery.

• The third method is the Rastelli procedure, which isadvised for patients with significant ventricular septal defect (VSD) and severe pulmonary stenosis. A baffle (tunnel) is created between the right and left atria, improving the blood's oxygen saturation.

Hypoplastic Left Heart Repair:

• This type of congenital heart disease is rare and is characterized by incomplete development of the left side of the heart. It needs to be treated immediately as babies with this disease struggle to survive without treatment.

• A complicated heart surgery is performed in three stages. The first stage includes the Norwood surgery within the first week of life. In this surgery, new blood vessels are created from the aorta and the pulmonary artery and are responsible for blood transport throughout the body.

• The second stage includes the bi-directional Glenn shunt operation, which is performed when the infant's age is between four to six months. This procedure reduces the workload on the left heart.

• The third stage involves the Fontan procedure and is performed when the infant is between the ages of 18 months to three years old. This procedure ensures that the oxygenated blood does not mix with deoxygenated blood.

Truncus Arteriosus Repair:

• A rare type of congenital heart defect, truncus arteriosus is a disease in which one blood vessel comes out of the ventricles instead of two blood vessels. If not treated, it adds extra pressure to the heart, and excess blood flows to the lungs, damaging its blood vessels with time.

• Surgical repair is done within the first few days of the infant’s life. It involves the separation of the aortic trunk and patching of the defects. A connection is subsequently made between the right ventricle and pulmonary arteries.

• In most cases, a single surgery may not be efficient in treating the defect, thereby warranting a second one.

What Measures Can Reduce the Risk of Developing a Congenital Heart Defect?

Avoiding high-risk factors can prevent the development of congenital heart diseases. Pregnant women can take the following measures to reduce the risk of delivering an infant with congenital heart defects-

• Avoiding the use of recreational drugs.

• Managing diabetes.

• Getting regular fetal scans and tests to help identify defects as early as possible.

• Avoid smoking as well as second-hand smoke.

• Avoiding alcohol.

• Before consuming any medication, ensure it is safe during pregnancy.

Conclusion

An abnormality found in the heart’s structure or function at birth is referred to as congenital heart disease. Such diseases can have defects ranging from mild to severe. Some cases might not require any intervention, and they resolve independently, whereas others might require surgical intervention. With advancements in science and technology, identifying and treating such defects has been easier. Hence, time is of the essence, and it is crucial to identify these defects at the earliest so that timely intervention can be made, improving the quality of life.