Double inlet left ventricle (DILV) is a congenital heart condition in which the heart chambers and valves are defective. As a result, the heart ventricles are replaced by a single pumping chamber. This is therefore one of the single or common ventricle defects.
The Normal Heart Structure
Normally, the heart has four chambers, and two of them are ventricles or pumping chambers, while two are atria or receiving chambers. The right atrium empties deoxygenated blood into the right ventricle which pumps blood to the lungs through the pulmonary artery. The left atrium receives and empties the oxygenated blood in the lungs into the left ventricle, which pumps it to the entire body through the aorta. These two parallel circulations are never mingled in the ordinary course.
In children with DILV, there is only one left ventricle and the right ventricle is poorly developed. Both the left and right atria empty their contents into the left ventricle. This means that oxygenated and deoxygenated blood mix in this chamber, and this oxygen-poor mixture is then pumped to the lungs as well as to the body.
Types of DILV
In some people with DILV, the great vessels leading from the ventricle are transposed. That is, the aorta leaves the hypoplastic right ventricle, while the pulmonary trunk leaves the large left ventricle.
DILV can also occur if there is a significant ventricular septal defect.
Associated defects include:
- Pulmonary atresia
- Pulmonary valve stenosis
- Coarctation of the aorta
DILV may produce the following symptoms:
- Tiring quickly while feeding
- Cyanosis, or a dusky gray or blue color to the lips, around the mouth, or nails, due to improper oxygenation of the blood
- Failure to thrive, which means poor weight gain and growth
- Failure to feed well
- Swelling of the abdomen and legs
- Breathing difficulty
Clinical examination will show the presence of cyanosis as well as a heartbeat which is faster than normal, and abnormal heart sounds, also called heart murmurs. Signs of heart failure, such as dilated veins in the neck and swelling of the lower extremities, may also be detected.
There are several tests that may be needed to diagnose and guide the treatment of double inlet left ventricle. These may include:
- An electrocardiogram to detect an abnormal heart rhythm.
- A chest X-ray to detect the shape and size of the heart, as well as the presence of fluid at the lung bases, which is a sign of heart failure.
- Cardiac catheterization, involving the passing of a flexible thin tube into the heart, to help show the position and size of the arteries.
- An ultrasound examination of the heart, called an echocardiogram, to show the internal anatomy and functioning of the heart.
- Magnetic resonance imaging of the heart to show the internal structure of the heart valves and chambers in greater detail.
The definitive management of DILV is surgery. In most cases, a series of two to three surgeries will be required to correct the malformation. The first surgery is typically carried out when the baby is a few days old, following which the baby will be put on close monitoring and heart medication. These may include anticoagulants, diuretics, digitalis and blood pressure medications.
The procedure which is usually staged at the age of 4-6 months is called the Hemi-Fontan or bidirectional Glenn operation. The last surgery (the Fontan procedure) is carried out between the age of 1.5 and 3 years. Following this procedure, the cyanosis is permanently corrected and the supply of oxygen is sufficient to allow the child to thrive.
In very severe cases, or when other anomalies are present, a heart transplant may be the only option for the child’s survival.
The prognosis of a baby who has DILV depends on the severity of the defect as well as the presence of other cardiac abnormalities. In addition, the baby’s health plays a major role in determining the extent to which surgical treatment is successful.