There are many different forms of single ventricle defects. They can involve one or more valves in the heart and a ventricle that does not pump effectively. In almost all cases, a single ventricle defect means that blood flow to your body or to your lungs is less than it should be. Some common types of single ventricle defects include:

• Hypoplastic left heart syndrome. This means that the left side of the heart has not developed enough.

• Pulmonary atresia. This is when there is no pulmonary valve. This valve separates the right ventricle from a pathway that leads to the lungs.

• Tricuspid atresia. This is when there is no tricuspid valve. This valve separates the right atrium from the right ventricle.

Most people with a single ventricle defect have surgery as a child. Even if you had surgery, you may be at risk for some problems that often affect adults who were born with a congenital heart defect. These may include:

• Heart failure.

• Heart rhythm problems (arrhythmias).

• Heart infections (endocarditis).

• Liver problems.

• Leaky heart valves.

The cause of this condition is usually not known. Possible causes include:

• Changes in genes or chromosomes during foetal development.

• Factors that affect the mother, such as environment, medicines, or dietary choices.

The following factors may make a person more likely to have this condition:

• Having a family history of congenital heart defects.

• Having certain genetic conditions, such as Down syndrome.

You may continue to have some symptoms of the heart defect as an adult even if you had surgery to correct the defect as a baby or child. Your symptoms depend on the type of defect you were born with. If you have had surgery, the success of the surgery also makes a difference. Your symptoms may include:

• Bluish skin and lips (cyanosis), especially after exercise.

• Low energy.

• Frequent infections.

• A heart rate that is too fast (tachycardia) or too slow (bradycardia).

• Fluid build-up in your abdomen or legs (oedema).

• Shortness of breath, especially when exercising.

It is important to have regular check-ups with your heart specialist (cardiologist) to make sure you are not developing any complications. Your cardiologist will ask if you have any new symptoms and will do a physical examination. You may also have tests, such as:

• Electrocardiogram (ECG or EKG) to check for arrhythmias.

• ECG during exercise (stress test).

• Echocardiogram to visualise your heart and check for size, shape and functional changes.

• Blood tests to check your liver function.

• Using a portable type of ECG that you wear over a period of time (Holter or event monitoring).

• Checking the blood flow through your heart and coronary arteries. This is done using cardiac catheterisation, which involves:

  • Inserting a long thin tube (catheter) through a vein in your arm or groin.

  • Injecting dye into the blood that is entering your heart. This dye passes through your heart and coronary arteries, and your cardiologist observes the dye on an X-ray machine.

Treatment may include:

• Medicines:

  • To control your heart rate.

  • To control your heart’s ability to pump blood throughout your body.

  • To control your blood pressure.

  • To prevent blood clots from forming in your heart.

• A pacemaker to regulate your heart rate.

• Surgery to repair or replace a leaky heart valve.

• A heart transplant if heart failure develops. This is rare.

Lifestyle

• Exercise as instructed by your healthcare provider. You may need to limit exercise that takes a lot of effort, such as weight lifting or competitive sports.

• Eat a heart-healthy diet and maintain a healthy weight. Work with a diet specialist (dietitian), if necessary.

• Do not use any products that contain nicotine or tobacco. These products include cigarettes, chewing tobacco and vaping devices, such as e-cigarettes. If you need help quitting, ask your healthcare provider.

• Do not abuse drugs or alcohol.

• If you are a woman and you become pregnant or want to become pregnant, you will need care from a cardiologist and a pregnancy specialist (obstetrician), both of whom should be familiar with managing heart defects during pregnancy.

General instructions

• Keep a record of your medical information to share with your healthcare providers. These records may include:

  • The type of single ventricle defect you were born with.

  • Surgeries you have had.

  • Medicines you are taking.

• Ask your healthcare provider if you need to take antibiotics before certain procedures.

• Take over-the-counter and prescription medicines only as instructed by your healthcare provider.

• Keep all follow-up appointments. This is important.