What is Truncus Arteriosus?
Normally there are two main blood vessels leaving the heart. One is the aorta that carries blood to the body. The other is the pulmonary artery that carries blood to each lung.
Instead of having a separate pulmonary artery and aorta, each with its own three-leafed valves, babies with truncus arteriosus have only one great blood vessel or trunk leaving the heart. It then branches into blood vessels that go to the lungs and the body.
This great vessel usually has one large valve. It may have between two and five leaflets. Usually this great vessel sits over both the left and right ventricle. The upper portion of the wall between these two chambers is missing. This results in a ventricular septal defect (VSD) . In rare cases, there is not a ventricular septal defect.
View 2D images of Truncus Arteriosis.
Signs and Symptoms of Truncus Arteriosus
A baby with truncus arteriosus begins to have problems in the first week of life. Their oxygen levels are often lower than normal. This results in a cyanosis (bluish color of the skin).
Because of the large amount of blood flow to the lungs with this defect, congestive heart failure (CHF) develops in the first week or two of life. On a chest X-ray, the heart looks big. The lung fields look hazy. This indicates pulmonary over-circulation (extra blood to the lungs).
Signs of congestive heart failure are fast breathing, wheezing, trouble breathing, grunting or very noisy breathing, increased work of breathing (pulling under the ribs, nasal flaring) and restlessness.
The liver may be large. Most often parents report fast breathing, poor feeding, and a bluish color of the skin. The signs and symptoms often get worse when the infant eats.
Diagnosis of Truncus Arteriosus
The diagnosis may be suspected by physical examination. The echocardiogram will confirm the presence of truncus arteriosus.
This heart defect may also be diagnosed on fetal echocardiograms. It is one of the cardiac defects that may be found on screening ultrasounds. Early diagnosis of the defect allows for prompt intervention at the time of birth.
A cardiac catheterization may be done on rare occasions if the anatomy appears very unusual.
Treatment of Truncus Arteriosus
Initial treatment begins with stabilizing the infant. Medications to control congestive heart failure are often started.
Surgery is typically done in the first few weeks of life after the infant is stabilized.
The surgical repair of truncus arteriosus uses the heart-lung bypass machine for support. It involves three major parts:
- Separating the pulmonary arteries from the main truncus
- Closing the ventricular septal defect using a patch
- Creating a connection between the right ventricle and the pulmonary arteries using a conduit (an artificial tube).
Infants will need to be watched closely in the Cardiac Intensive Care Unit while they recover.
The use of mechanical ventilation, special monitoring lines, and intravenous medicines is typical during this period.
Gradually, as the infant recovers from surgery, the supporting measures are weaned. The infant is changed to medications by mouth and begins to work on feeding.
Time in the hospital after surgery ranges from one to three weeks in most cases.
Results for Treatment of Truncus Arteriosus
As the child grows, he or she will be followed by a cardiologist. They will need echocardiograms and EKGs.
Typically, there are no physical restrictions on the child. As a child grows, the conduit will need to be replaced because the artificial tube does not grow with the child, and they slowly outgrow it. This can often initially be done through minimally invasive procedures in the cardiac cath lab. The child will eventually need an open-heart surgery to replace the right ventricle to pulmonary artery conduit with a larger one.
These surgeries are tolerated very well with a hospitalization of less than a week
Problems with the truncal valve are more serious. They can significantly affect the early and late outcomes of these children. The leakier or more narrowed this valve is, the greater the chance that some intervention will need to be done (on average within five to seven years) to prevent severe damage to the heart.
Adult and Adolescent Management
Adult patients with truncus arteriosus may present in two ways. The first is that they are still blue or cyanotic, always with very high blood pressures in their lungs. This presentation is very rare since most patients are diagnosed in infancy when they have heart failure symptoms. They need lifelong doctor visits and management.
The second presentation is after surgical repair in childhood. All such patients need lifelong follow up care with their doctor. Many of these patients have valved conduits connecting their right heart chambers to their pulmonary arteries. These conduits fail over time. They need expert assessment and judgment as to how best to manage them. Many postsurgical patients have small abnormalities of their “truncal valve.” This may lead to a lot of leakage with enlargement of the left heart chambers and the need for valve replacement.
Some adults with truncus arteriosus have a genetic basis for the condition. It’s important that this be identified so that other concerns of their genetic abnormality can be addressed.
Learn more about the Adolescent and Adult Congenital Heart Disease Program.
