Truncus arteriosus

Definition:

A type of congenital heart disease characterized by a single arterial trunk supplying pulmonary (lung), coronary (heart), and systemic (body) circulation.

Causes, incidence, and risk factors:

In normal circulation, the pulmonary artery arises from the right ventricle and the aorta arises from the left ventricle. Coronary arteries, which supply the heart muscle, arise from the aorta, just above the valve at the entrance of the aorta.

In truncus arteriosus, a single arterial trunk arises from the ventricle. A large ventricular septal defect (VSD) is always present along with a truncus defect, essentially making the right and left ventricles into a single chamber. Blood flows at a higher systemic pressure through all the arteries (the pressure to and from the lungs is normally low).

Systemic pressure in the lung circulation results in increased blood flow through the lungs, an increased cardiac work load, and eventual heart failure. The higher pressure eventually damages the pulmonary vessels (the blood vessels in the lungs) causing increased pulmonary resistance. When this happens pulmonary blood flow decreases and the person becomes cyanotic (blue).

Affected people often have shortness of breath (dyspnea), fatigue, and heart failure. As with most children with cyanotic congenital heart disease, their growth and physical development may be poor. Untreated, this condition can be fatal in the first few years of life.