Truncus arteriosus

Overview

In children with truncus arteriosus, only one artery connects to the heart instead of two. This big blood vessel, called the truncus, connects with the heart through one large valve that allows blood from the two lower chambers of the heart, called the ventricles, to leave the heart. Blood passes into both the lungs and the body from this large blood vessel.

Below this abnormal valve, there is nearly always an abnormal opening between the two ventricles, called a ventricular septal defect or VSD, which allows oxygenated and non-oxygenated blood to mix.

To understand truncus arteriosus, it helps to understand the healthy heart and how it functions. The heart consists of four chambers: the two upper chambers, called atria, where blood enters the heart, and the two lower chambers, called ventricles, where blood is pumped out of the heart. The flow between the chambers is controlled by a set of valves that act as one-way doors.

Normally blood is pumped from the right side of the heart through the pulmonary valve and the pulmonary artery to the lungs, where the blood is filled with oxygen. From the lungs, the blood travels back down to the left atrium and left ventricle. The newly oxygenated blood is then pumped through another big blood vessel, called the aorta, to the rest of the body.

Signs & symptoms

Babies with truncus arteriosus usually don't get enough oxygen in their blood so they may have a bluish cast to their skin, especially around the nose and mouth. Their lungs get too much blood, which could result in congestive heart failure. Congestive heart failure is when one or more chambers of the heart fail to keep up with the volume of blood flowing through them. Symptoms of congestive heart failure include breathlessness, rapid breathing, excessive sweating, and restlessness.

Diagnosis

The diagnosis of truncus arteriosus in confirmed with an echocardiogram, a procedure that uses sound waves to create a moving picture of the baby's heart. Sometimes, doctors may need to insert dye into the baby's heart through a thin, flexible tube called a catheter in order to determine the exact shape of the truncus. The catheter usually is inserted into a blood vessel in the groin and then threaded up into the heart.

Treatment

Your baby may receive medication to control congestive heart failure. However, treatment for truncus arteriosus itself requires open heart surgery.

The surgery involves the following steps:

• Separate the pulmonary artery from the truncus. The truncus then becomes part of the aorta, the blood vessel that distributes oxygenated blood from the heart to the rest of the body.
• Close the ventricular septal defect (VSD) with a patch, usually made of GoreTex, a flexible plastic.
• Insert a tube with a valve in it to connect the newly freed pulmonary artery to the heart's right ventricle. The valve may be artificial or may be made out of human tissue. This tube will probably have to be replaced as the child grows, usually after five to 10 years, but occasionally earlier or later.