Double inlet left ventricle (DILV) is a congenital heart defect that affects the valves of the heart. Congenital means it is present from birth. Babies born with this condition have only one working lower chamber (ventricle) in their heart.

DILV is one of several heart defects known as single (or common) ventricle defects. People with this condition generally have a large left ventricle (the pumping chamber of the heart that supplies the body with blood), and a small right ventricle (the pumping chamber that supplies the lungs with blood).

In the normal heart, the right and left lower chambers (ventricles) receive blood from the right and left upper chambers (atria). The pulmonary artery then carries oxygen-poor blood to the lungs from the right ventricle, and the aorta carries oxygen-rich heart to the rest of the body from the left ventricle.

However, in those with DILV, only the left lower heart chamber is developed, and both upper chambers carry blood into this ventricle. This means that oxygen-rich blood mixes with oxygen-poor blood. The mixture is then carried into the body and the lungs.

DILV can occur with transposition of the great vessels (in which the aorta arises from the small right ventricle and the pulmonary artery arises from the left ventricle), or it can occur with the arteries arising from the normal places. Blood flows from the right to left ventricles through a ventricular septal defect (VSD).

Double inlet left ventricle occurs in about 5 - 10 of 100,000 live births. The problem most likely occurs early in the pregnancy, when the baby's heart develops. However, the exact cause of DILV is unknown.

Patients with DILV often also have other heart problems, such as:

• Coarctation of the aorta
• Pulmonary atresia
• Pulmonary valve stenosis

Symptoms of DILV may include:

• Becoming tired easily, especially during feeding
• Bluish skin color (the lips may also be blue)
• Failure to gain weight and grow
• Pale skin (pallor)
• Poor feeding
• Sweating
• Swollen legs or abdomen
• Trouble breathing

Signs of DILV may include:

• Abnormal heart rhythm, as seen on an electrocardiogram
• Build-up of fluid around the lungs
• Heart failure
• Heart murmur
• Rapid heartbeat

Tests to diagnose DILV may include:

• Measurement of the electrical activity in the heart (electrocardiogram, or ECG)
• Passing a thin, flexible tube into the heart to examine the arteries (cardiac catheterization)
• Ultrasound exam of the heart (echocardiogram)
• Using magnets to create images of the heart (MRI)

Surgery is needed to improve blood circulation through the body and into the lungs. The most common surgeries to treat DILV are the ones leading up to the Fontan operation, which may require several stages. (Each stage in the Fontan procedure is a separate surgery.)

These surgeries are similar to the ones used to treat hypoplastic left heart syndrome and tricuspid atresia.

The first surgery may be needed within the baby's first few days of life. Afterward, the baby will usually go home. The child will need to take one or more daily medications and be closely followed by a pediatric cardiologist, who will decide when the second stage of surgery should be done.

The next surgery (or first surgery, if the baby didn't need the procedure mentioned above) is called the bidirectional Glenn shunt or Hemifontan procedure. This surgery is usually done when the child is 4 - 6 months old.

After the child has had the above operations, he or she may still look blue (cyanotic). The final step is called the Fontan procedure. This surgery is usually performed when the child is 18 months - 3 years old. After this final step, the baby is no longer cyanotic.

The Fontan operation does not create normal circulation in the body, but it creates the type of circulation a child can live and grow with. However, even this surgery carries many risks and complications.

A child may need additional types of surgeries for related defects or to extend survival while waiting for the Fontan procedure.

The doctor may prescribe your child medication before and after surgery. Medications may include:

• Anticoagulants to prevent blood clotting
• ACE inhibitors to reduce blood pressure
• Digoxin

For the most severe cases of DILV, a heart transplant may be recommended.

All children with congenital heart disease should take antibiotics before dental treatment. This prevents infections around the heart, a common problem with heart disease.

DILV is usually a very complex, hard-to-treat heart defect. How well the baby does depends on several factors. They include:

• Baby's overall condition at the time of diagnosis and treatment
• Presence of other heart abnormalities
• Severity of the defect

Advances in surgical techniques allow many infants with DILV to reach adulthood. However, many of these children and adults require regular follow-ups, face many complications, and may be limited in the type of physical activities they can pursue.

Complications of DILV include:

• Clubbing (thickening of the nail beds) on toes and fingers (late sign)
• Congestive heart failure
• Death
• Frequent pneumonia
• Heart rhythm problems
• High blood pressure in the lungs
• Lung damage

Park MK. Park: Pediatric Cardiology for Practitioners, 5th ed. Philadelphia, PA: Mosby Elsevier; 2008:283-287:chap 14.

Kliegman RM, Behrman RE, Jenson HB, Stanton BF. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier;2007.

Townsend Jr. CM, Beauchamp RD, Evers BM, et al, eds. Townsend: Sabiston Textbook of Surgery, 18th ed. Philadelphia, PA: Saunders Elsevier; 2008:1777-1783: chap 43.