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Truncus arteriosus: a rare heart defect

Truncus arteriosus is a rare congenital heart defect because it occurs in less than one in ten thousand live births. One percent of all congenital heart defects is truncus arteriosus. This abnormality can be corrected surgically, but the child will always have to remain under the supervision of the cardiologist. This is because the child will have to undergo surgery several times during his life.

  • Truncus arteriosus
  • Possible causes
  • Symptoms
  • Diagnostics
  • Therapy
  • Prognosis


Truncus arteriosus

Truncus arteriosis is an opening between the chambers of the heart, also called a ventricular septal defect. In addition, only one blood vessel, called the truncus, with one valve goes to the body from both chambers. Ultimately, that blood vessel splits into the coronary arteries, the aorta and the pulmonary artery. Because these blood vessels arise from that one blood vessel, the oxygen-rich blood from the left ventricle is mixed with the oxygen-poor blood from the right ventricle and is then pumped with the same pressure to the coronary arteries, the aorta and the pulmonary artery.

Possible causes

Truncus arteriosus is a congenital heart defect. This means that something went wrong in the development of the heart during pregnancy. In this case, a mistake was made in dividing the main artery into two separate arteries, namely the aorta and the pulmonary artery.In some children with truncus arteriosus, this is due to a chromosome abnormality. This concerns the micro deletion of chromosome number 22. This abnormality is called the 22q11 deletion or the DiGeorge syndrome.


In the first weeks after birth, the baby shows the first symptoms of truncus arteriosus. This may include the following symptoms:

  • Weight gain is slow
  • Bad drinking
  • Gray color
  • Rapid breathing
  • Fast heart rate
  • Tired



To diagnose a truncus arteriosus, the heart must be properly mapped. The following studies are being carried out for this purpose:

  • Electrocardiogram (ECG)
  • Echo of the heart
  • Chest X-ray, this is an X-ray of the heart
  • Cardiac catheterization



This test shows the electrical activity of the heart. But it says nothing about the anatomy and pumping function of the heart. However, this examination may show arrhythmias and thickening of the heart muscle of the right and left ventricle.

Echo of the heart

An ultrasound of the heart is already made in the twentieth week of pregnancy so that children with a congenital heart defect can be treated immediately after birth. Parents can also choose to terminate the pregnancy based on the ultrasound and all information about the heart defect. The ultrasound is used to map the anatomy and function of the heart. The function of the heart can be analyzed because the contractility of the chambers and the speed of blood flow are measured.

Chest X-ray

On a chest X-ray, doctors can assess the size and shape of the heart and the vascular filling of the lungs. However, in babies there is a possibility of an incorrectly measured enlarged heart because the thymus, which lies in front of the heart, can be so large that the actual heart shadow hides behind it.

Cardiac catheterization

During cardiac catheterization, a catheter is inserted into the vein or artery in the groin. This catheter measures the saturation in the different compartments of the heart and in the large vessels. In addition, blood pressure is measured directly because this method is more reliable than the Doppler method (this method is performed during the ultrasound). Finally, the anatomy of the heart is visualized using contrast fluid.


The surgeons’ aim with surgery is to change the abnormal blood circulation to normal blood circulation. To achieve this, the gap between the two rooms is closed with a patch. In addition, the surgeons will insert a flexible tube with a valve system from the pulmonary artery to the right ventricle to deliver blood from the right ventricle to the pulmonary artery. The valve that has been present from the beginning will then serve as the aortic valve.


If the child survives the operation, the prognosis is good. The quality of life is also good and the child can participate in a normal school and in most sports activities unless a chromosome abnormality has also been diagnosed. Then the quality of life depends on the severity of the chromosome abnormality. However, the child will have to be operated on more often in the future because the inserted tube and valve do not grow with the child.