Heart problems in babies

Heart Disease

One baby in 100 is born with heart or circulation problems. With improvements in ultrasound scan techniques, most can now be detected while the baby is still in the womb

Causes of heart problems

It’s thought that most heart problems in babies are due to faulty genes. From conception, when sperm and egg combine, a complex construction process occurs to create a human embryo. We all carry a small number of faulty genes and if there’s a fault in the gene signalling, a structural heart problem may appear.

In small communities, where relatives are more likely to marry, there is less variation in the genes and it is more likely that both parents will carry the same rare genetic faults. This situation is known as a small gene pool, and it’s dangerous because genetic conditions such as heart abnormalities are more likely to occur. In larger communities, where there’s more mixing of different genes, genetic problems are less common.

A proportion of babies with heart malformations have problems with the chromosomes, which can be detected by tests during pregnancy, providing an early clue that the child may be at particular risk. For example, many pregnant women are screened for Down’s syndrome (where there are three rather than two copies of chromosome number 21), in which up to 40 per cent of babies are born with a heart problem.

There are other causes of congenital heart disease too. For example, mothers with diabetes have a two per cent chance of having a baby with a heart problem.

However, most of the babies born with heart problems don’t come from high-risk groups. The reason is simply that this is a comparatively rare, almost unpredictable condition – and there are only small numbers of high-risk people in the population.

Diagnosing heart problems

The majority of heart problems in babies are detected at a routine ultrasound scan, usually at 18 to 20 weeks, although some aren’t discovered until after the birth. If you have worries, talk to your GP or obstetrician. If they suspect problems, they may refer you to a specialist unit for further tests.

At about 19 weeks gestation, a baby’s heart is less than 1cm across and weighs only 1g or so (compared with 500g for an average adult heart). It also beats more than twice as fast as an adult’s.

The circulation of a foetus is different from that of a newborn baby, being connected to a placenta and having three extra channels that must close or reverse at birth.

Good-quality ultrasound equipment is essential to look at the tiny, fast-moving cardiac structures. Even so, ultrasound images appear grainy – it requires practice and an experienced eye to identify problems.

Advances such as the colour flow doppler detect the movement of red blood cells, highlighting areas of abnormal blood flow that may indicate circulation problems. These may have been missed by a conventional scan.

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Who Needs a Pacemaker?

Heart Disease

Doctors recommend pacemakers for many reasons. The most common reasons are bradycardia and heart block.

Bradycardia is a heartbeat that is slower than normal. Heart block is a disorder that occurs if an electrical signal is slowed or disrupted as it moves through the heart.

Heart block can happen as a result of aging, damage to the heart from a heart attack, or other conditions that disrupt the heart’s electrical activity. Some nerve and muscle disorders also can cause heart block, including muscular dystrophy.

Your doctor also may recommend a pacemaker if:

Aging or heart disease damages your sinus node’s ability to set the correct pace for your heartbeat. Such damage can cause slower than normal heartbeats or long pauses between heartbeats. The damage also can cause your heart to switch between slow and fast rhythms. This condition is called sick sinus syndrome.
You’ve had a medical procedure to treat an arrhythmia called atrial fibrillation. A pacemaker can help regulate your heartbeat after the procedure.
You need to take certain heart medicines, such as beta blockers. These medicines can slow your heartbeat too much.
You faint or have other symptoms of a slow heartbeat. For example, this may happen if the main artery in your neck that supplies your brain with blood is sensitive to pressure. Just quickly turning your neck can cause your heart to beat slower than normal. As a result, your brain might not get enough blood flow, causing you to feel faint or collapse.
You have heart muscle problems that cause electrical signals to travel too slowly through your heart muscle. Your pacemaker may provide cardiac resynchronization therapy (CRT) for this problem. CRT devices coordinate electrical signaling between the heart’s lower chambers.
You have long QT syndrome, which puts you at risk for dangerous arrhythmias.
Doctors also may recommend pacemakers for people who have certain types of congenital heart disease or for people who have had heart transplants. Children, teens, and adults can use pacemakers.

Before recommending a pacemaker, your doctor will consider any arrhythmia symptoms you have, such as dizziness, unexplained fainting, or shortness of breath. He or she also will consider whether you have a history of heart disease, what medicines you’re currently taking, and the results of heart tests.

Diagnostic Tests

Many tests are used to detect arrhythmias. You may have one or more of the following tests.

EKG (Electrocardiogram)
An EKG is a simple, painless test that detects and records the heart’s electrical activity. The test shows how fast your heart is beating and its rhythm (steady or irregular).

An EKG also records the strength and timing of electrical signals as they pass through your heart. The test can help diagnose bradycardia and heart block (the most common reasons for needing a pacemaker).

A standard EKG only records the heartbeat for a few seconds. It won’t detect arrhythmias that don’t happen during the test.

To diagnose heart rhythm problems that come and go, your doctor may have you wear a portable EKG monitor. The two most common types of portable EKGs are Holter and event monitors.

Holter and Event Monitors
A Holter monitor records the heart’s electrical activity for a full 24- or 48-hour period. You wear one while you do your normal daily activities. This allows the monitor to record your heart for a longer time than a standard EKG.

An event monitor is similar to a Holter monitor. You wear an event monitor while doing your normal activities. However, an event monitor only records your heart’s electrical activity at certain times while you’re wearing it.

For many event monitors, you push a button to start the monitor when you feel symptoms. Other event monitors start automatically when they sense abnormal heart rhythms.

You can wear an event monitor for weeks or until symptoms occur.

Echocardiography
Echocardiography (echo) uses sound waves to create a moving picture of your heart. The test shows the size and shape of your heart and how well your heart chambers and valves are working.

Echo also can show areas of poor blood flow to the heart, areas of heart muscle that aren’t contracting normally, and injury to the heart muscle caused by poor blood flow.

Electrophysiology Study
For this test, a thin, flexible wire is passed through a vein in your groin (upper thigh) or arm to your heart. The wire records the heart’s electrical signals.

Your doctor uses the wire to electrically stimulate your heart. This allows him or her to see how your heart’s electrical system responds. This test helps pinpoint where the heart’s electrical system is damaged.

Stress Test
Some heart problems are easier to diagnose when your heart is working hard and beating fast.

During stress testing, you exercise to make your heart work hard and beat fast while heart tests, such as an EKG or echo, are done. If you can’t exercise, you may be given medicine to raise your heart rate.