Congenital Heart Defects - "Holes in the Heart"

Holes in the heart are simple congenital (kon-JEN-ih-tal)  heart defects. Congenital heart defects are problems  with the heart's structure that are present at birth. These defects change the normal flow of blood through the heart.

Your heart has two sides, separated by an inner wall called the septum. With each heartbeat, the right side of your heart receives oxygen-poor blood from your body and pumps it to your lungs. The left side of your  heart receives oxygen-rich blood from your lungs and pumps it to your body.

The septum prevents mixing of blood between the two sides of the heart. However, some babies are born with holes in the upper or lower septum.  The septum is the thin membrane of heart tissue which separates the left from the right atrium, and the ventricular septum is a more muscular tissue which separates the left from the right ventricle.

A hole in the septum between the heart's two upper chambers is called an atrial septal defect (ASD).  A hole in the septum between the heart's two lower chambers is called a ventricular septal defect (VSD). 

ASDs and VSDs  allow blood to pass from the left side of the heart to the right side. This means that oxygen-rich blood can mix with oxygen-poor blood. As a result, some  oxygen-rich blood is pumped to the lungs instead of out to the body. 

Over the past few decades, the diagnosis and treatment of ASDs and VSDs have greatly improved. Children who have  simple congenital heart defects can survive to adulthood and live normal, active, and productive lives because their heart defects close on their own or have been repaired. 

How the Heart Works 

To understand holes in the heart, it's helpful to know how a healthy heart works. Your child's heart is a muscle about the size of  his or her fist. The heart works like a pump and beats  upwards of a 100,000 times a day. 

The heart has two sides, separated by an inner wall called the septum. The right side of the heart pumps blood to the lungs to pick up oxygen. Then, oxygen-rich blood returns from the lungs to the left side of the heart, and the left side pumps it to the body. 

The heart has four chambers and four valves and is connected to various blood vessels. Veins are the blood vessels that carry blood from the body to the heart. Arteries are the blood vessels that carry blood away from the heart to the body. 

Heart Chambers 

The heart has four chambers or "rooms." 

• The atria (AY-tree-uh) are the two upper chambers that collect blood as it comes into the heart. 
• The ventricles (VEN-trih-kuhls) are the two lower chambers that pump blood out of the heart to the lungs or other parts of the body. 

• The tricuspid (tri-CUSS-pid) valve is in the right side of the heart, between the right atrium and the right ventricle. 
• The pulmonary (PULL-mun-ary) valve is in the right side of the heart, between the right ventricle and the entrance to the pulmonary artery, which carries blood to the lungs. 
• The mitral (MI-trul) valve is in the left side of the heart, between the left atrium and the left ventricle. 
• The aortic (ay-OR-tik) valve is in the left side of the heart, between the left ventricle and the entrance to the aorta, the artery that carries blood to the body. 

• The first sound—the "lub"—is made by the mitral and tricuspid valves closing at the beginning of systole (SIS-toe-lee). Systole is when the ventricles contract, or squeeze, and pump blood out of the heart. 
• The second sound—the "DUB"—is made by the aortic and pulmonary valves closing at the beginning of diastole (di-AS-toe-lee). Diastole is when the ventricles relax and fill with blood pumped into them by the atria. 

• The pulmonary artery carries blood pumped from the right side of the heart to the lungs to pick up a fresh supply of oxygen. 
• The aorta is the main artery that carries oxygen-rich blood pumped from the left side of the heart out to the body. 
• The coronary arteries are the other important arteries attached to the heart. They carry oxygen-rich blood from the aorta to the heart muscle, which must have its own blood supply to function. 

• The pulmonary veins carry oxygen-rich blood from the lungs to the left side of the heart so it can be pumped out to the body. 
• The superior and inferior vena cavae are large veins that carry oxygen-poor blood from the body back to the heart. 

For more information on how a healthy heart works, go to the Diseases and Conditions Index How the Heart Works article. This article contains animations that show how your heart pumps blood and how your heart's electrical system works. 

Types of Holes in the Heart 

Atrial Septal Defect 

An atrial septal defect (ASD) is a hole in the part of the septum that separates the atria (the upper chambers of the heart). This hole allows oxygen-rich blood from the left atrium to flow into the right atrium instead of flowing into the left ventricle as it should. 

This means that oxygen-rich blood gets pumped back to the lungs, where it has just been, instead of going to the body. 

An ASD can be small or large. Small ASDs allow only a little blood to flow from one atrium to the other. Small ASDs don't affect the way the heart works and may not need any special treatment. Many small ASDs close on their own as the heart grows during childhood. 

Medium to large ASDs allow more blood to leak from one atrium to the other, and they're less likely to close on their own, and may require surgery to correct or prevent serious longterm complications as listed below.  Most children who have ASDs have no symptoms, even if they have large ASDs. 

The three major types of ASDs (Atrial Septal Defects) are

• Secundum. This defect is in the middle of the atrial septum. It's the most common form of ASD. About 8 out of every 10 babies born with ASDs have secundum defects. At least half of all secundum ASDs close on their own. However, this is less likely if the defect is large. 
• Primum.  This defect is in the lower part of the atrial septum. It often occurs along with problems in the heart valves that connect the upper and lower heart chambers. Primum defects aren't very common, and they don't close on their own. 
• Sinus venosus.  This defect is in the upper part of the atrial septum, near where a large vein (the superior vena cava) brings oxygen-poor blood from the upper body to the right atrium. Sinus venosus defects are rare, and they don't close on their own. 

Atrial Septal Defect Complications 

Over time, if an ASD isn't repaired, the extra blood flow to the right side of the heart and lungs may cause heart problems. Usually, most of these problems don't show up until adulthood, often around age 30 or later. Complications are rare in infants and children. 

Possible complications include: 

• Right heart failure. An ASD causes the right side of the heart to work harder because it has to pump extra blood to the lungs. Over time, the heart may become tired from this extra work and not pump well. 
• Arrhythmias (ah-RITH-me-ahs). Extra blood flowing into the right atrium through an ASD can cause the atrium to stretch and enlarge. Over time, this can lead to arrhythmias (irregular heartbeats). Arrhythmia symptoms may include palpitations or a rapid heartbeat. 
• Stroke. Usually, the lungs filter out small blood clots that can form on the right side of the heart. Sometimes a blood clot can pass from the right atrium to the left atrium through an ASD and be pumped out to the body. This type of clot can travel to an artery in the brain, block blood flow, and cause a stroke. 
• Pulmonary hypertension (PH). PH is increased pressure in the pulmonary arteries. These arteries carry blood from your heart to your lungs to pick up oxygen. Over time, PH can damage the arteries and small blood vessels in the lungs. They become thick and stiff, making it harder for blood to flow through them. 

These problems develop over many years and don't occur in children. They also are rare in adults because most ASDs either close on their own or are repaired in early childhood. 

Ventricular Septal Defect 

A ventricular septal defect (VSD) is a hole in the part of the septum that separates the ventricles (the lower chambers of the heart). The hole allows oxygen-rich blood to flow from the left ventricle into the right ventricle instead of flowing into the aorta and out to the body as it should. 

An infant who is born with a VSD may have a single hole or more than one hole in the wall that separates the two ventricles. The defect also may occur by itself or with other congenital heart defects. 

Doctors classify VSDs based on the: 

• Size of the defect. 
• Location of the defect. 
• Number of defects. 
• Presence or absence of a ventricular septal aneurysm—a thin flap of tissue on the septum. This tissue is harmless and can help a VSD close on its own. 

VSDs can be small or large. Small VSDs don't cause problems and often may close on their own. Because small VSDs allow only a small amount of blood to flow between the ventricles, they're sometimes called restrictive VSDs. Small VSDs don't cause any symptoms. 

Medium VSDs are less likely to close on their own. They may require surgery to close and may cause symptoms during infancy and childhood. 

Large VSDs allow a large amount of blood to flow from the left ventricle to the right ventricle. They're sometimes called nonrestrictive VSDs. A large VSD is less likely to close completely on its own, but it may get smaller over time. Large VSDs often cause symptoms in infants and children, and surgery usually is needed to close them. 

VSDs are found in different parts of the septum. 

• Membranous VSDs are located near the heart valves. These VSDs can close at any time. 
• Muscular VSDs are found in the lower part of the septum. They're surrounded by muscle, and most close on their  own during early childhood. 
• Inlet VSDs are located close to where blood enters the ventricles. They're less common than membranous and muscular VSDs. 
• Outlet VSDs are found in the part of the ventricle where blood leaves the heart. These are the rarest type of VSD. 

Ventricular Septal Defect Complications 

Over time, if a VSD isn't repaired, it may cause heart problems. A moderate to large VSD can cause: 

• Heart failure. Infants who have large VSDs may develop heart failure because the left side of the heart pumps blood into the right ventricle in addition to its normal work of pumping blood to the body. The increased workload on the heart also increases the heart rate and the body's demand for energy. 
• Growth failure, especially in infancy. A baby may not be able to eat enough to keep up with his  or her body's increased energy demands. As a result, the baby may lose weight or not grow and develop normally. 
• Arrhythmias (irregular heartbeats). The extra blood flowing through the heart can cause areas of the heart to stretch and enlarge. This can disturb the heart's normal electrical activity, leading to arrhythmias. 
• Pulmonary Hypertension (PH). The high pressure and high volume of extra blood pumped through a large VSD into the right ventricle and lungs can scar the lung's delicate arteries. Today, PH rarely develops because most large VSDs are repaired in infancy. 

What Causes Holes in the Heart? 

Mothers of children who are born with atrial septal defects (ASDs), ventricular septal defects (VSDs), or other types of heart defects often think that they did something wrong during the pregnancy to cause the problems. However, most of the time, doctors don't know why congenital heart defects develop. 

Heredity may play a role in some heart defects. For example, a parent who  has a congenital heart defect is slightly more likely than other people to have a child with the problem. Very rarely, more than one child in a family is born with a heart defect. 

Children who have genetic disorders, such as Down syndrome, often have congenital heart defects. Half of all babies who have Down syndrome have congenital heart defects. 

Smoking during pregnancy also has  been linked to several congenital heart defects, including septal defects. 

Scientists continue to search for the causes of congenital heart defects.