Congenital Heart Disease: What Is A Single Ventricle Heart Defect?

A single ventricle heart defect is one of many different types of congenital heart disease — heart diseases a person is born with. A single ventricle defect develops when one of the two bottom chambers of the heart, called the ventricles, don’t work correctly. Some people with a single ventricle defect might also be missing a valve, which ensures one-way flow of the blood.

Children born with single ventricle heart defects will often develop cyanosis and turn a bluish color because their body is not getting enough oxygen, alerting medical professionals that there is a problem if the condition was not diagnosed before birth. The amount of oxygen the body gets will depend largely on the type and severity of the defect as well as where it is located. Therefore, while some children may only present with mild cyanosis, others will have a severe lack of oxygen and need immediate treatment. Fortunately, single ventricle heart defects are quite rare, affecting only five in 100,000 newborns.

What are the different types of single ventricle heart defects?

There are several different types of single ventricle heart defects, each of which is unique. These include:

• Tricuspid atresia — in which the right side of the heart is not developed sufficiently.
• Hypoplastic left heart syndrome — in which the left side of the heart is not properly developed; a severe single ventricle heart defect.
• Mitral valve atresia
• Single Left ventricle
• Double inlet left ventricle — both atria empty blood into the left ventricle, while the right ventricle is underdeveloped.
• Double outlet right ventricle — the opposite problem. 
• Pulmonary atresia
• Ebstein’s anomaly
• Atrioventricular canal defect

Most of these conditions are very rare. 

What are the signs and symptoms associated with single ventricle heart defects?

Symptoms and signs associated with single ventricle heart defects will vary significantly depending on the type of defect and how severe it is. Symptoms associated with the defect include:

• Cyanosis, a lack of oxygen in the body that leads the child to have a bluish or purplish tint on the lips, skin and nails.
• Breathing difficulties
• Problems feeding
• Feeling lethargic, sleepy or generally unresponsive

How are single ventricle defects diagnosed?

Single ventricle heart defects are often diagnosed before birth by performing a fetal echocardiography. However, in some cases, single ventricle heart defects are not diagnosed until the baby has already been born. A bluish tint, trouble breathing, or a heart murmur (an abnormal sound due to turbulent blood flow) can lead a doctor to look further. In that case, they will likely order an echocardiogram, which uses ultrasound waves to create a detailed image of the heart to diagnose heart defects.

What are the treatments for single ventricle heart defects?

Treatment plans will depend on the type and severity of single ventricle heart defect. Babies born with single ventricle heart defects will need to spend a lot of time in the hospital, as a series of open-heart surgeries (staged reconstruction) await them. The following procedures can be a part of this intervention:

• Norwood procedure
• Hemi-fontan
• Glenn operation
• Fontan procedure

What is the prognosis for patients with single ventricle heart defects?

While babies born with single ventricle heart defects were not expected to live past infancy in the not-so-distant past, advances in medicine and science mean that the most patients will live much longer after staged reconstruction. Unfortunately, the expected lifespan of these patients remains unknown, since the life-saving interventions were introduced fairly recently.

What medical care can children with single ventricle heart defects expect?

Children with single ventricle heart defects will need to be monitored closely and should be under the care of a cardiologist, even after surgical intervention has been completed. Before that time comes, parents can also expect numerous diagnostic procedures between surgeries. 

Some patients with single ventricle heart defects will be placed on blood-thinners, and the need for follow-up operations and even a heart transplant can also arise. In the meanwhile, however, children can live full lives that include physical activity.

What are the complications that patients may experience as they get older?

Patients with single ventricle heart defects can experience several different types of problems as they get older. These complications can be related to the patient’s age, the age at which they had surgerical interventions, and the types of surgeries that have been conducted. The types of problems that can develop in patients with single ventricle heart defects include:

• Arrhythmia, which refers to an abnormal heart beat. Patients can have a faster or a slower heart rate.
• Patients may have problems with fluid retention, especially in the abdomen or lower extremities.
• After surgical intervention, some patients with single ventricle heart defects can develop varicose veins.
• Patients have a higher risk of weakening and failing heart muscle.
• Patients have a higher risk of having blood clots in their heart, thus requiring anticoagulation therapy.