Truncus Arteriosus

Normally there are two main blood vessels leaving the heart: the aorta, carrying blood to the body, and the pulmonary artery that branches immediately to carry blood to each lung.

Instead of having a separate pulmonary artery and aorta, each with its own three-leafed valves, a baby with truncus arteriosus has only one great blood vessel or trunk leaving the heart, which then branches into blood vessels that go to the lungs and the body.

This great vessel usually has one large valve which 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, resulting in what is known as a ventricular septal defect (VSD) . In rare cases, the ventricular septal defect is absent.

A baby with truncus arteriosus usually begins to have problems in the first week of life. His or her oxygen levels are often slightly lower than normal, resulting in cyanosis.

Because of the excessive amount of blood flow to the lungs with this anomaly, congestive heart failure (CHF) develops in the first week or two of life. On chest X-ray, the heart looks big and the lung fields look hazy, indicating pulmonary overcirculation.

Signs of congestive heart failure are rapid breathing, shortness of breath, wheezing, grunting or very noisy breathing, nasal flaring, retractions, and restlessness.

The liver may be large due to a backup of blood or systemic congestion. Neck vein distention, poor feeding, and facial swelling are also seen.

Most often parents report rapid breathing, poor feeding, and a bluish color of the skin, especially around the mouth and nose. The signs and symptoms often increase when the infant eats.

While the diagnosis may be suspected by physical examination, the echocardiogram will confirm the presence of truncus arteriosus. The anatomy of the great vessels, the single, complex truncal valve and the ventricular septal defect are easily seen.

cardiac catheterization may be done on rare occasions if anatomy appears very unusual, or the diagnosis is made later as information is needed regarding the pressures in the pulmonary arteries. In most cases, however, the echocardiogram gives enough information to plan for surgery.

Initial treatment begins with stabilizing the infant. Medications to control congestive heart failure such as diuretics are often begun.

Surgical correction is typically carried out in the first few weeks of life after the infant is maximally stabilized.

The surgical repair of truncus arteriosus requires the use of heart-lung bypass machine support. It involves three major components:

  • Separating the pulmonary arteries from the main truncus (the truncus will remain as the first part of the aorta)
  • Closure of the ventricular septal defect using a patch
  • Creating a connection between the right ventricle and the pulmonary arteries using a conduit, usually a homograft pulmonary artery.

Most infants will require a period of very close monitoring in the Cardiac Intensive Care Unit while their heart function recovers from the major reconstruction.

The use of mechanical ventilation, special monitoring lines, and strong intravenous medications is typical during this period.

Gradually, as the heart function stabilizes, the supporting measures may be withdrawn and conversion to oral medications and attention to feeding dominate the management program.

Time in hospital following surgery may vary from one to three weeks in most cases.

Currently more than 90 percent of children survive repair of truncus arteriosus. As the child grows, he or she will be followed by a cardiologist.

Typically, there will be no physical restrictions imposed on the child. As a child grows, the conduit that was used to connect the right ventricle and pulmonary arteries will not, and this will lead to obstruction to blood flow. The progression of this narrowing is followed by the cardiologist using physical examination and echocardiograms.

Recommendation for surgery to replace the right ventricle to pulmonary artery conduit with a larger one is usually made before any symptoms would be evident.

This conduit will often need to be replaced two or three times during childhood to accommodate for growth. These operations are typically tolerated very well with a hospitalization of less than a week.

Problems with the truncal valve are more serious and can significantly affect the early and late mortality of these children. The more leaky (or narrowed) this valve is, the greater the chance that some intervention has to be done sooner than later (on average within five to seven years) to prevent severe damage to the heart.

Adult patients with truncus arteriosus may present in two ways.  The first is that they are still blue or cyanotic, almost always with very high blood pressures in their lungs. Such patients will definitely have problems and will require lifelong expert surveillance and management.

The second presentation is after surgical repair in childhood. All such patients require lifelong expert surveillance. Many of these patients have valved conduits connecting their right heart chambers to their pulmonary arteries. These conduits usually malfunction or fail over time, and require expert assessment and judgment as to how best to manage them. Many postsurgical patients have residual abnormalities of their “aortic valve.” This may lead to excessive leakage with consequent 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 manifestations of their genetic abnormality can be managed properly.

Learn more about the Adolescent and Adult Congenital Heart Disease Program


Last Updated 12/2013