Introduction
Birth defects are structural abnormalities that can affect any part of the body, causing various health problems and affecting overall health. Approximately one in 100 babies are born with heart defects in the United States every year, and one in four infants born with heart defects may have critical congenital heart disease. Some heart defects can be mild and treated, whereas others, such as critical congenital heart defects, require surgeries over several years.
However, due to advances in medical care and treatment modalities, the quality of life of these infants has greatly improved.
What Is Congenital Heart Disease?
Congenital heart disease (CHD), also called congenital heart defect, is a condition that a child is born with. It can affect the shape and functioning of the heart and can be mild or serious. These are the most common types of birth defects and can affect different parts of the baby’s heart. Critical congenital heart diseases (CCHD) are serious heart defects, and such infants require surgery or other treatments within the first year of life. The signs and symptoms in infants mainly depend on the type and severity of the specific defect. Some of the common symptoms of CHD in preterm infants are difficulty breathing, blue-tinted lips and nails, heart murmur, weak pulse, sleepiness, and tiredness during feeding. A few examples of congenital heart disease include:
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Atrial septal defect (ASD) (a hole in the wall of the heart that divides the upper chambers).
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Ventricular septal defect (VSD) ( a hole in the wall of the heart that divides the lower chambers).
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Atrioventricular septal defect (holes between the heart's chambers on the right and left sides).
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Coarctation of the aorta (COA) (narrowing of the aorta).
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Tetralogy of Fallot (four defects in the heart and its blood vessels)
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Double outlet right ventricle (both the heart's major arteries are connected to the right ventricle).
How Does Congenital Heart Disease Affect Preterm Infants?
Heart defects in preterm infants can occur during the first six weeks of pregnancy when the heart is still developing. The exact cause of these congenital defects is unknown but can be attributed to gene or chromosome abnormalities and can run in families. Approximately 15 percent of congenital heart defects in infants are linked to genetic or chromosomal changes. Certain conditions in pregnant mothers, such as obesity, lupus (autoimmune disorder), rubella (flu-like symptoms), preexisting diabetes, phenylketonuria (inability to break down the amino acid called phenylalanine), smoking, consumption of alcohol, or medications such as statins, angiotensin-converting enzyme inhibitors, Thalidomide, Lithium, Isotretinoin, etc. can also increase the infant’s risk of developing congenital heart diseases.
Congenital heart defects can slow down the blood flow or be blocked. It can also cause blood to flow in the wrong direction or to the wrong body area. The blood vessels may not have sufficient oxygen to carry throughout the body. Some defects in blood flow can also cause fluid accumulation in the lungs, known as pulmonary edema or lung congestion, making it difficult for infants to breathe. Infants with severe heart defects may also develop congestive cardiac failure (heart failure) if the heart is unable to pump blood effectively. In conditions such as coarctation of the aorta, the blood flow is reduced, which causes the heart muscles to work harder than usual, weakening the heart muscles and causing other problems. In infants with double-outlet right ventricles, the aorta is connected to the right ventricle instead of the left, or a hole may also be present between the two ventricles. This causes the transportation of oxygen-poor blood to other parts of the body.
How Is Congenital Heart Disease Managed in Preterm Infants?
Premature infants with congenital heart disease represent a challenging population to manage for clinicians as they require unique considerations, and the interaction between CHD and prematurity is poorly understood. Studies have suggested that some premature newborns are likely to have congenital heart disease, and fetuses with CHD are most probably born premature. Preterm infants have more than two-fold higher risk of developing cardiovascular abnormalities than full-term babies.
Gestational age and birth weight are considered important factors in determining the timing of surgical repair. Physiologic challenges for the management of preterm infants with CHD include cardiac development, increased fluid requirements, immature renal function, other genetic abnormalities, poor oxygenation, immature gut, adequate blood pressure, and other factors. Cardiac catheterization is a procedure in which a thin tube is inserted through a vein into the heart to repair minor cardiac defects. However, heart surgery is necessary to repair major defects in the heart or blood vessels, replace a heart valve, or place a device to help the heart pump blood. A heart transplantation may be recommended if all other treatment options are ineffective. All preterm infants require regular medications and frequent monitoring throughout their lives, even if the congenital defects are treated. The management of preterm infants with CHD mainly depends on the type and severity of the condition. These include:
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Coarctation of the Aorta: If the condition is severe and develops soon after the birth, surgery is recommended within the first few days of life to restore the blood flow through the blood vessel. It includes removing the narrowed section of the aorta and reconnecting the remaining ends, which is performed by inserting a catheter into the aorta and widening it with a balloon or a metal stent.
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Patent Ductus Arteriosus (PDA): It is a congenital heart disease with an opening between the aorta and pulmonary artery. It affects the blood flow to the lungs and requires catheterization or surgery. It can also be treated shortly after birth through medications or by keyhole surgery. In some cases, the duct may be required to be shut, which is performed by open heart surgery.
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ASD and VSD: The treatment of these conditions mainly depends on the size of the hole in the wall of the heart chamber. Small septal defects may not require treatment, but larger ones need surgical intervention.
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Tetralogy of Fallot: If the baby is born with severe symptoms, surgery is necessary soon after birth to close the hole in the heart and open the narrowed pulmonary valve. However, if symptoms are less severe, surgery is mostly performed when the infant is four to six months old. Regular monitoring of the infants is required even after surgery, and if any leaking from the pulmonary valve is observed, catheter intervention or open heart surgery is preferred.
Conclusion
Recent advances in healthcare technology have led to developments in pediatric cardiac surgery, anesthesia, and other specialties. Hence, most congenital heart diseases can be managed partially or completely. This has also reduced surgical mortality significantly, even in complex cases, and improved the quality of life in most of the preterm infants with CHD. However, due to age and certain special requirements, treating preterm infants can be challenging for many specialists. Early intervention, optimal management, an expert team effort, and appropriate post-surgical care are necessary for the successful management of CHD in preterm infants.
