Heart Size Of A Newborn: What's Normal?

The heart of a newborn baby is about the size of a walnut. Despite their small size, newborn hearts can have a multitude of life-threatening abnormalities in the arrangement of the vessels, valves, and chambers.

A newborn's heart is the size of a walnut

A newborn's heart is about the size of a walnut. While small, it is a complex organ, with four chambers and a tree of major blood vessels. The coronary arteries deliver oxygen and nutrients to the heart muscle.

The heart of a newborn is a delicate organ and can have a multitude of life-threatening abnormalities in the arrangement of the vessels, valves, and chambers. These defects can be corrected with surgery, but the complexity of the heart's structure means that this is intricate work.

Surgeons must be highly skilled to operate on newborn hearts, and the procedures can be lengthy and risky. In some cases, the infant must be placed in a state of "deep hypothermia" to slow metabolism and reduce the body's demand for oxygen during the operation. This is because, during much of the operation, the infant's aorta is in pieces, and so they have no circulation.

Despite the challenges, surgical techniques have advanced to the point that many life-threatening defects can be corrected, giving newborns a chance at a healthy life.

Newborns can have life-threatening abnormalities

A newborn's heart is about the size of a walnut. However, despite their small size, newborn hearts can have a multitude of life-threatening abnormalities.

Congenital heart defects (CHDs) are the most common type of birth defect, affecting nearly 1 in 100 babies in the United States each year. These defects occur when a baby's heart doesn't develop normally during pregnancy, resulting in structural problems that change the way the heart pumps blood. CHDs can range from mild issues that require little to no treatment, to critical and life-threatening conditions that demand immediate medical attention.

Critical CHDs, known as critical congenital heart defects or critical congenital heart disease, require surgery or other treatment within the first year of life. Without intervention, these defects can lead to serious health complications and even death. Examples of critical CHDs include coarctation of the aorta, where the aorta is too narrow, and hypoplastic left heart syndrome, where the left side of the heart doesn't form correctly.

The complexity and urgency of treating these abnormalities are evident in cases such as baby Hazell, who required immediate surgery after birth. The leading surgeon, Dr. James Jaggers, operated on Hazell from the right side of the operating table, showcasing the intricate nature of these procedures.

Early detection and specialized care are crucial for newborns with heart abnormalities. Prenatal ultrasounds and fetal echocardiograms can identify potential problems, allowing for prompt referrals to specialized cardiac neonatal intensive care units. These units are equipped with advanced technologies like ECMO and 3-D printing, enabling surgeons to provide tailored treatments and enhance outcomes for infants undergoing complex cardiac procedures.

Heart defects are often congenital

A newborn's heart is about the size of a walnut, but despite their small size, newborn hearts can have a multitude of life-threatening abnormalities. Heart defects are often congenital, meaning they are present at birth. Congenital heart defects (CHDs) occur when a baby's heart doesn't develop normally during pregnancy, usually soon after conception, and they are the most common type of birth defect.

There are several categories of possible childhood heart problems, including defects from faulty embryo development, misplaced structures, structures that don't develop properly, and heart rhythm disturbances. These defects can range from simple problems, such as "holes" between chambers of the heart, to severe malformations, such as the absence of one or more chambers or valves.

CHDs can change the way the heart pumps blood, causing it to flow too slowly, go in the wrong direction, or be blocked completely. The most common types of CHDs include septal defects (holes in the heart), heart valve defects, and defects in the large blood vessels that carry blood in and out of the heart. These defects can have varying effects on a person's circulatory system and can increase the risk of developing certain medical conditions, such as pulmonary hypertension, infective endocarditis, congestive heart failure, and kidney and liver disease.

CHDs affect nearly 1% of births per year, and while virtually all children with simple defects survive into adulthood, those with more complex problems may face limitations and developmental delays. In some cases, CHDs can be identified prenatally through ultrasounds and fetal echocardiograms, and surgery may be required within the first year of life or even immediately after birth.

Heart defects can be detected with an ultrasound

The heart of a newborn baby is about the size of a walnut. Despite their small size, newborn hearts can have a multitude of life-threatening abnormalities in the arrangement of the vessels, valves, and chambers.

Fetal echocardiography is typically performed between 18 and 22 weeks of pregnancy, although it can be done as early as 14 to 15 weeks. It is often carried out following a routine ultrasound that indicates a potential issue, such as abnormalities in the baby's heart rate or rhythm. A fetal echocardiogram may also be recommended if there is a family history of congenital heart disease or other risk factors.

While fetal echocardiography is an effective tool, it may not always identify mild defects. In some cases, heart defects may only be detected after birth, especially if there are no noticeable symptoms. For example, some defects may not cause any noticeable symptoms for several months or even years. In these cases, further testing, such as an echocardiogram, electrocardiogram (ECG), or chest X-ray, can help diagnose congenital heart disease.

The detection of heart defects during pregnancy or after birth is crucial for developing a care plan and ensuring the best possible outcome for the baby. It allows medical professionals to monitor the baby's health in utero and create a specialized birth plan with a team of specialists ready to provide immediate care if needed.

Heart defects can be repaired with surgery

A newborn's heart is about the size of a walnut, but despite their minute size, newborn hearts can have a multitude of life-threatening abnormalities. Thankfully, many heart defects can be repaired with surgery.

Congenital heart defects are heart problems that a baby is born with. Surgery is often needed if the defect could harm the child's long-term health or well-being. In some cases, congenital heart disease may not be detected until adulthood.

There are many types of pediatric heart surgery, and the type of surgery required depends on the nature of the defect. Here are some examples of defects that can be repaired with surgery:

• Patent ductus arteriosus (PDA) ligation: A PDA occurs when a blood vessel that runs between the aorta and the pulmonary artery fails to close shortly after birth. This can usually be closed off with medicine, but if this doesn't work, surgery may be required. The surgeon can close the PDA with a small surgical cut on the left side of the chest or through a minimally invasive procedure that doesn't involve surgery.
• Coarctation of the aorta repair: Coarctation of the aorta occurs when a part of the aorta has a very narrow section, making it difficult for blood to get through. This can be repaired by cutting the narrow section and making it bigger with a patch, removing the narrow section and stitching the remaining ends together, or using a patch from the left subclavian artery to enlarge the narrow section.
• Atrial septal defect (ASD) repair: An ASD is a hole in the atrial septum, the wall between the left and right atria (upper chambers) of the heart. This can sometimes be closed without open-heart surgery by inserting a wire into a blood vessel that goes to the heart and placing two small umbrella-shaped "clamshell" devices on either side of the septum to close the hole. Open-heart surgery may also be performed to close the septum with stitches or a patch.
• Ventricular septal defect (VSD) repair: A VSD is a hole in the ventricular septum, the wall between the left and right ventricles (lower chambers) of the heart. Small VSDs often close on their own by age 1, but larger VSDs or those in certain locations may need to be closed with surgery, typically with a patch.
• Tetralogy of Fallot repair: Tetralogy of Fallot is a heart defect that usually includes four defects in the heart and causes the baby to turn a bluish colour (cyanosis). Open-heart surgery is needed, typically when the child is between 6 months and 2 years old. The surgery involves closing the VSD with a patch, placing a patch on the right ventricle and main pulmonary artery to improve blood flow to the lungs, and opening the thickened muscle (stenosis).
• Transposition of the great vessels repair: In a normal heart, the aorta comes from the left side, and the pulmonary artery from the right. In transposition of the great vessels, these arteries come from the opposite sides. Correcting this requires open-heart surgery, usually performed shortly after birth. The most common repair is an arterial switch, where the aorta and pulmonary artery are divided and then connected to the correct ventricles.

These are just a few examples of heart defects that can be repaired with surgery. Cardiac surgeons are highly skilled and can perform intricate and complex procedures to correct a range of congenital heart problems.

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