In the normal heart, two separate great arteries arise from the hearts main pumping chambers (called ventricles) and act as large pipes or conduits for blood to flow away from the heart. One of these great vessels is called the aorta (the main artery for most of the body) and the other is called the pulmonary artery (the main artery to the lungs). A relatively rare congenital heart defect called truncus arteriosus is said to be present when only one great vessel forms, instead of two.
One large vessel comes off the heart (instead of the normal two) and branches of this supply all of the various organs. The one artery is called a common trunk, thus explaining the name truncus. Without two separate arteries to regulate flow properly (like in the normal heart), the blood flow through these branches is not normal and blood flows abnormally more to some organs and abnormally less to others. There are also large holes between the chambers of the heart (ASD and VSD). The condition is a very serious one and before surgery could be done, the heart would become enlarged and fail (known as heart failure), and the patients would all die as newborns and infants.
Surgery
Fortunately, surgery for truncus arteriosus has become safe, and most patients can undergo successful repair in the newborn period. The surgery is a difficult one, however, as it is a major repair that requires several important steps and is best done in the first few days of life and thus in the smallest babies. The repair requires that the one common trunk be separated into two, and the major holes (ASD and VSD) in the heart be closed.
Making two arteries out of one requires that some kind of artificial artery (known as a conduit) be used to make up for the one that is missing. There are many different types of conduits, and we will use whatever is the correct fit and type for your particular child’s repair. This conduit has important consequences later in life (see below).
For patch material, we prefer to use something called pericardium (the tough lining around the heart) or Gore-Tex (the same durable material that rain jackets are made from). Both are time-tested materials which produce no problems for the child as they grow, even years later. Surgery for truncus always requires an incision and cardiopulmonary bypass.
In our program, our heart surgeons are specially trained in newborn and infant heart operations and despite the rareness of the defect, we all have performed many successful repairs of truncus. Between 2009-13 alone, we have repaired 16 consecutive patients with a 100 percent success and survival rate. Many more patients with truncus that has been previously repaired have undergone additional surgery by our surgeons (see below) with similar success rates. It is important to remember that some patients with truncus also have valve problems that require repair as well, and this can complicate surgery and raise the risk. If this is true for your newborn, our surgeons will specifically discuss this aspect with you as it pertains to your child.
It is also very important to remember that ALL patients with truncus who undergo successful repair will always require additional surgery at least several more times in life; this is because the conduit will wear out and the child will outgrow it. For example, a conduit that is appropriate for a newborn or infant will later be too small for a 4- to 5-year-old. The child’s own immune system also affects the conduits, and they wear out over time, even if the child does not grow.
As your child grows, we can eventually place a large enough conduit so that further procedures can be done in the catheterization lab without even making an incision. This is exciting technology called catheter valve placement, but most patients require at least several operations to arrive at this point.