Truncus arteriosus is a rare congenital heart defect in which the pulmonary and aortic valves fail to separate completely. This lack of separation results in one large artery, instead of two, leaving the heart. Truncus arteriosus also presents with a large ventricular septal defect. Children may also have a malformed thymus gland, which can affect immune response to even the simplest of viruses.
This disorder necessitates early repair because pressure to the lungs is significantly increased by the large ventricular septal defect and the malformation of the valves. Too much blood gets to the lungs, creating high pressure that must be addressed early to avoid permanent damage. Additionally, too little oxygenated blood gets to the body, which can result in failure to thrive, cyanosis or "blue baby", clubbing of the extremities and exhaustion.
Until the 1980s, truncus arteriosus was usually addressed in two surgeries. The first surgery placed a band around the pulmonary valve to reduce blood flow to the lungs. This gave the baby time to grow before repairing the ventricular septal defect, and separating and suturing the pulmonary and aortic arteries.
However, pulmonary banding is rarely used now, because improvement in surgical techniques and delivery of anesthesia allows for repair soon after a child is born. Single step repair has a high success rate, even when performed on children just a few days old. Further repair may be required to the valves as the child ages. The pulmonary valve is particularly susceptible to becoming leaky over time, and may need replacement. A bovine, porcine or donor valve is used. Valve replacement has a low incidence of risk and is considered as one of the simplest cardiac repairs.
Children with repaired truncus arteriosus require lifetime follow-up by a cardiologist. Usually, after the careful scrutiny during the first few months of a repair, cardiologists see the child once a year. During a regular visit, the cardiologist usually performs an echocardiogram, or sonogram of the heart, to evaluate the repair and to ensure that pulmonary valve leakage is not significant. In some cases, pulmonary valve leakage after a repair must be evaluated via cardiac catheterization. This outpatient procedure is considered minimally invasive and does not require general anesthesia, although some forms of conscious sedation may be used to keep the child comfortable and sleeping throughout.
The child with repaired truncus arteriosus is usually allowed to participate in normal activities, but the cardiologist may recommend refraining from competitive sports, particularly as the child ages. Children may also be on low dose aspirin to prevent blood clots that could lead to stroke. Most cardiologists also recommend prophylactic antibiotics prior to dental exams and procedures.
Truncus arteriosus is a significant and serious set of heart defects. It is sometimes linked to a condition called Di George, which involves other anatomical defects and can complicate health both before and after repair. Children without Di George are generally expected to have normal life expectancy and quality of life.
