Friday, 26 April 2013

How Are Holes in the Heart Diagnosed?

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Doctors usually diagnose holes in the heart based on a physical exam and the results from tests and procedures. The exam findings for an atrial septal defect (ASD) often aren't obvious. Thus, the diagnosis sometimes isn't made until later in childhood or even in adulthood.
Ventricular septal defects (VSDs) cause a very distinct heart murmur. Because of this, a diagnosis usually is made in infancy.

Specialists Involved

Doctors who specialize in diagnosing and treating heart problems are called cardiologists. Pediatric cardiologists take care of babies and children who have heart problems. Cardiac surgeons repair heart defects using surgery.

Physical Exam

During a physical exam, your child's doctor will listen to your child's heart and lungs with a stethoscope. The doctor also will look for signs of a heart defect, such as a heart murmur or signs of heart failure.

Diagnostic Tests and Procedures

Your child's doctor may recommend several tests to diagnose an ASD or VSD. These tests also will help the doctor figure out the location and size of the defect.

Echocardiography

Echocardiography (echo) is a painless test that uses sound waves to create a moving picture of the heart. The sound waves (called ultrasound) bounce off the structures of the heart. A computer converts the sound waves into pictures on a screen.
Echo allows the doctor to clearly see any problem with the way the heart is formed or the way it's working.
Echo is an important test for both diagnosing a hole in the heart and following the problem over time. Echo can show problems with the heart's structure and how the heart is reacting to the problems. This test will help your child's cardiologist decide whether and when treatment is needed.

EKG (Electrocardiogram)

An EKG is a simple, painless test that records the heart's electrical activity. The test shows how fast the heart is beating and its rhythm (steady or irregular). It also records the strength and timing of electrical signals as they pass through the heart.
An EKG can detect whether one of the heart's chambers is enlarged, which can help diagnose a heart problem.

Chest X Ray

A chest x ray is a painless test that creates pictures of the structures in the chest, such as the heart, lungs, and blood vessels.
This test can show whether the heart is enlarged. A chest x ray also can show whether the lungs have extra blood flow or extra fluid, a sign of heart failure.

Pulse Oximetry

Pulse oximetry shows the level of oxygen in the blood. A small sensor is attached to a finger or ear. The sensor uses light to estimate how much oxygen is in the blood.

Cardiac Catheterization

During cardiac catheterization (KATH-e-ter-i-ZA-shun), a thin, flexible tube called a catheter is put into a vein in the arm, groin (upper thigh), or neck. The tube is threaded to the heart.
Special dye is injected through the catheter into a blood vessel or one of the heart's chambers. The dye allows the doctor to see the flow of blood through the heart and blood vessels on an x-ray image.
The doctor also can use cardiac catheterization to measure the pressure inside the heart chambers and blood vessels. This can help the doctor figure out whether blood is mixing between the two sides of the heart.
Doctors also use cardiac catheterization to repair some heart defects. For more information, go to "How Are Holes in the Heart Treated?"
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What Are the Signs and Symptoms of Holes in the Heart?

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Atrial Septal Defect

Many babies who are born with atrial septal defects (ASDs) have no signs or symptoms. However, as they grow, these children may be small for their age.
When signs and symptoms do occur, a heart murmur is the most common. A heart murmur is an extra or unusual sound heard during a heartbeat.
Often, a heart murmur is the only sign of an ASD. However, not all murmurs are signs of congenital heart defects. Many healthy children have heart murmurs. Doctors can listen to heart murmurs and tell whether they're harmless or signs of heart problems.
If a large ASD isn't repaired, the extra blood flow to the right side of the heart can damage the heart and lungs and cause heart failure. This generally doesn't occur until adulthood. Signs and symptoms of heart failure include:
  • Fatigue (tiredness)
  • Tiring easily during physical activity
  • Shortness of breath
  • A buildup of blood and fluid in the lungs
  • Swelling in the ankles, feet, legs, abdomen, and veins in the neck

Ventricular Septal Defect

Babies born with ventricular septal defects (VSDs) usually have heart murmurs. Murmurs may be the first and only sign of a VSD. Heart murmurs often are present right after birth in many infants. However, the murmurs may not be heard until the babies are 6 to 8 weeks old.
Most newborns who have VSDs don't have heart-related symptoms. However, babies who have medium or large VSDs can develop heart failure. Signs and symptoms of heart failure usually occur during the baby's first 2 months of life.
The signs and symptoms of heart failure due to VSD are similar to those listed above for ASD, but they occur in infancy.
A major sign of heart failure in infancy is poor feeding and growth. VSD signs and symptoms are rare after infancy. This is because the defects either decrease in size on their own or they're repaired.
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Your Heart's Electrical System

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Your heart's electrical system controls all the events that occur when your heart pumps blood. The electrical system also is called the cardiac conduction system. If you've ever seen the heart test called an EKG (electrocardiogram), you've seen a graphical picture of the heart's electrical activity.
Your heart's electrical system is made up of three main parts:
  • The sinoatrial (SA) node, located in the right atrium of your heart
  • The atrioventricular (AV) node, located on the interatrial septum close to the tricuspid valve
  • The His-Purkinje system, located along the walls of your heart's ventricles
A heartbeat is a complex series of events. These events take place inside and around your heart. A heartbeat is a single cycle in which your heart's chambers relax and contract to pump blood. This cycle includes the opening and closing of the inlet and outlet valves of the right and left ventricles of your heart.
Each heartbeat has two basic parts: diastole and systole. During diastole, the atria and ventricles of your heart relax and begin to fill with blood.
At the end of diastole, your heart's atria contract (atrial systole) and pump blood into the ventricles. The atria then begin to relax. Your heart's ventricles then contract (ventricular systole), pumping blood out of your heart.
Each beat of your heart is set in motion by an electrical signal from within your heart muscle. In a normal, healthy heart, each beat begins with a signal from the SA node. This is why the SA node sometimes is called your heart's natural pacemaker. Your pulse, or heart rate, is the number of signals the SA node produces per minute.
The signal is generated as the vena cavae fill your heart's right atrium with blood from other parts of your body. The signal spreads across the cells of your heart's right and left atria.
This signal causes the atria to contract. This action pushes blood through the open valves from the atria into both ventricles.
The signal arrives at the AV node near the ventricles. It slows for an instant to allow your heart's right and left ventricles to fill with blood. The signal is released and moves along a pathway called the bundle of His, which is located in the walls of your heart's ventricles.
From the bundle of His, the signal fibers divide into left and right bundle branches through the Purkinje fibers. These fibers connect directly to the cells in the walls of your heart's left and right ventricles (see yellow on the picture in the animation).
The signal spreads across the cells of your ventricle walls, and both ventricles contract. However, this doesn't happen at exactly the same moment.
The left ventricle contracts an instant before the right ventricle. This pushes blood through the pulmonary valve (for the right ventricle) to your lungs, and through the aortic valve (for the left ventricle) to the rest of your body.
As the signal passes, the walls of the ventricles relax and await the next signal.
This process continues over and over as the atria refill with blood and more electrical signals come from the SA node.
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What Causes Holes in the Heart?

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Mothers of children who are born with atrial septal defects (ASDs), ventricular septal defects (VSDs), or other heart defects may think they did something wrong during their pregnancies. However, most of the time, doctors don't know why congenital heart defects occur.
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 who has 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.
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Circulation and Blood Vessels

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Your heart and blood vessels make up your overall blood circulatory system. Your blood circulatory system is made up of four subsystems.

Arterial Circulation

Arterial circulation is the part of your circulatory system that involves arteries, like the aorta and pulmonary arteries. Arteries are blood vessels that carry blood away from your heart. (The exception is the coronary arteries, which supply your heart muscle with oxygen-rich blood.)
Healthy arteries are strong and elastic (stretchy). They become narrow between heartbeats, and they help keep your blood pressure consistent. This helps blood move through your body.
Arteries branch into smaller blood vessels called arterioles (ar-TEER-e-ols). Arteries and arterioles have strong, flexible walls that allow them to adjust the amount and rate of blood flowing to parts of your body.

Venous Circulation

Venous circulation is the part of your circulatory system that involves veins, like the vena cavae and pulmonary veins. Veins are blood vessels that carry blood to your heart.
Veins have thinner walls than arteries. Veins can widen as the amount of blood passing through them increases.

Capillary Circulation

Capillary circulation is the part of your circulatory system where oxygen, nutrients, and waste pass between your blood and parts of your body.
Capillaries are very small blood vessels. They connect the arterial and venous circulatory subsystems.
The importance of capillaries lies in their very thin walls. Oxygen and nutrients in your blood can pass through the walls of the capillaries to the parts of your body that need them to work normally.
Capillaries' thin walls also allow waste products like carbon dioxide to pass from your body's organs and tissues into the blood, where it's taken away to your lungs.

Pulmonary Circulation

Pulmonary circulation is the movement of blood from the heart to the lungs and back to the heart again. Pulmonary circulation includes both arterial and venous circulation.
Oxygen-poor blood is pumped to the lungs from the heart (arterial circulation). Oxygen-rich blood moves from the lungs to the heart through the pulmonary veins (venous circulation).
Pulmonary circulation also includes capillary circulation. Oxygen you breathe in from the air passes through your lungs into your blood through the many capillaries in the lungs. Oxygen-rich blood moves through your pulmonary veins to the left side of your heart and out of the aorta to the rest of your body.
Capillaries in the lungs also remove carbon dioxide from your blood so that your lungs can breathe the carbon dioxide out into the air.
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Types of Holes in the Heart

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Atrial Septal Defect

An atrial septal defect (ASD) is a hole in the part of the septum that separates the atria. (The atria are the upper chambers of the heart.)
An ASD allows oxygen-rich blood to flow from the left atrium into the right atrium, instead of flowing into the left ventricle as it should. So, instead of going to the body, the oxygen-rich blood is pumped back to the lungs, where it has just been.

Cross-Section of a Normal Heart and
a Heart With an Atrial Septal Defect

Figure A shows the normal structure and blood flow in the interior of the heart. Figure B shows a heart with an atrial septal defect. The hole allows oxygen-rich blood from the left atrium to mix with oxygen-poor blood from the right atrium.
Figure A shows the structure and blood flow inside a normal heart. Figure B shows a heart with an atrial septal defect. The hole allows oxygen-rich blood from the left atrium to mix with oxygen-poor blood from the right atrium.
An ASD can be small, medium, or large. Small ASDs allow only a little blood to flow from one atrium to the other. Small ASDs don't affect how the heart works and don't need any special treatment. Many small ASDs close on their own as the heart grows during childhood.
Medium and large ASDs allow more blood to leak from one atrium to the other. They're less likely to close on their own.
Most children who have ASDs have no symptoms, even if they have large ASDs.
The three major types of ASDs are:
  • Secundum. This defect is in the middle of the atrial septum and is 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. Primum defects often occur with heart valve problems. These 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. It's close to 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

If an ASD isn't repaired, the extra blood flow to the right side of the heart and lungs may cause heart problems. Most of these problems don't occur until adulthood, often around age 30 or later.
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 irregular heartbeats called arrhythmias. 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, though, a blood clot can pass from the right atrium to the left atrium through an ASD and be pumped out to the body. The 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 the heart to the 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 hard for blood to flow through them.
These problems develop over many years and rarely occur in infants and children. They also are rare in adults because most ASDs 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 ventricles are the lower chambers of the heart.)
A VSD allows oxygen-rich blood to flow from the left ventricle into the right ventricle, instead of flowing into the aorta as it should. So, instead of going to the body, the oxygen-rich blood is pumped back to the lungs, where it has just been.

Cross-Section of a Normal Heart and
a Heart With a Ventricular Septal Defect

Figure A shows the normal structure and blood flow in the interior of the heart. Figure B shows two common locations for a ventricular septal defect. The defect allows oxygen-rich blood from the left ventricle to mix with oxygen-poor blood in the right ventricle.
Figure A shows the structure and blood flow inside a normal heart. Figure B shows two common locations for a ventricular septal defect. The defect allows oxygen-rich blood from the left ventricle to mix with oxygen-poor blood in the right ventricle.
An infant who is born with a VSD may have one or more holes in the wall that separates the two ventricles. The defect also may occur alone or with other congenital heart defects.
Doctors will classify a VSD 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, medium, or large. Small VSDs don't cause problems and may close on their own. Small VSDs sometimes are called restrictive VSDs because they allow only a small amount of blood to flow between the ventricles. Small VSDs don't cause any symptoms.
Medium VSDs are less likely to close on their own. They may cause symptoms in infants and children. Surgery may be needed to close medium VSDs.
Large VSDs allow a lot of blood to flow from the left ventricle to the right ventricle. They're sometimes called nonrestrictive VSDs. Large VSDs likely won't close completely on their own, but they may get smaller over time.
Large VSDs often cause symptoms in infants and children. Surgery usually is needed to close large VSDs.
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 medium or large VSD can cause:
  • Heart failure. Infants who have large VSDs may develop heart failure. This is 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 infants. 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. 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 irregular heartbeats.
  • Pulmonary hypertension. 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 arteries. This problem is rare because most large VSDs are repaired in infancy.
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Heart Contraction and Blood Flow

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The animation below shows how your heart pumps blood. Click the "start" button to play the animation. Written and spoken explanations are provided with each frame. Use the buttons in the lower right corner to pause, restart, or replay the animation, or use the scroll bar below the buttons to move through the frames.
The animation shows how blood flows through the heart as it contracts and relaxes.

Heartbeat

Almost everyone has heard the real or recorded sound of a heartbeat. When your heart beats, it makes a "lub-DUB" sound. Between the time you hear "lub" and "DUB," blood is pumped through your heart and circulatory system.
A heartbeat may seem like a simple, repeated event. However, it's a complex series of very precise and coordinated events. These events take place inside and around your heart.
Each side of your heart uses an inlet valve to help move blood between the atrium and ventricle. The tricuspid valve does this between the right atrium and ventricle. The mitral valve does this between the left atrium and ventricle. The "lub" is the sound of the tricuspid and mitral valves closing.
Each of your heart's ventricles also has an outlet valve. The right ventricle uses the pulmonary valve to help move blood into the pulmonary arteries. The left ventricle uses the aortic valve to do the same for the aorta. The "DUB" is the sound of the aortic and pulmonary valves closing.
Each heartbeat has two basic parts: diastole (di-AS-toe-lee) and systole (SIS-toe-lee).
During diastole, the atria and ventricles of your heart relax and begin to fill with blood. At the end of diastole, your heart's atria contract (atrial systole) and pump blood into the ventricles.
The atria then begin to relax. Next, your heart's ventricles contract (ventricular systole) and pump blood out of your heart.

Pumping Action

Your heart uses its four valves to ensure your blood flows in only one direction. Healthy valves open and close in coordination with the pumping action of your heart's atria and ventricles.
Each valve has a set of flaps called leaflets or cusps that seal or open the valve. The cusps allow pumped blood to pass through the chambers and into your blood vessels without backing up or flowing backward.
Oxygen-poor blood from the vena cavae fills your heart's right atrium. The atrium contracts (atrial systole). The tricuspid valve located between the right atrium and ventricle opens for a short time and then shuts. This allows blood to enter the right ventricle without flowing back into the right atrium.
When your heart's right ventricle fills with blood, it contracts (ventricular systole). The pulmonary valve located between your right ventricle and pulmonary artery opens and closes quickly.
This allows blood to enter into your pulmonary arteries without flowing back into the right ventricle. This is important because the right ventricle begins to refill with more blood through the tricuspid valve. Blood travels through the pulmonary arteries to your lungs to pick up oxygen.
Oxygen-rich blood returns from the lungs to your heart's left atrium through the pulmonary veins. As your heart's left atrium fills with blood, it contracts. This event is called atrial systole.
The mitral valve located between the left atrium and left ventricle opens and closes quickly. This allows blood to pass from the left atrium into the left ventricle without flowing backward.
As the left ventricle fills with blood, it contracts. This event is called ventricular systole. The aortic valve located between the left ventricle and aorta opens and closes quickly. This allows blood to flow into the aorta. The aorta is the main artery that carries blood from your heart to the rest of your body.
The aortic valve closes quickly to prevent blood from flowing back into the left ventricle, which already is filling up with new blood.

Taking Your Pulse

When your heart pumps blood through your arteries, it creates a pulse that you can feel on the arteries close to the skin's surface. For example, you can feel the pulse on the artery inside of your wrist, below your thumb.
You can count how many times your heart beats by taking your pulse. You will need a watch with a second hand.
To find your pulse, gently place your index and middle fingers on the artery located on the inner wrist of either arm, below your thumb. You should feel a pulsing or tapping against your fingers.
Watch the second hand and count the number of pulses you feel in 30 seconds. Double that number to find out your heart rate or pulse for 1 minute.
The usual resting pulse for an adult is 60 to 100 beats per minute. To find your resting pulse, count your pulse after you have been sitting or resting quietly for at least 10 minutes.
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