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Persistent Truncus Arteriosus

By

Jeanne Marie Baffa

, MD, Sidney Kimmel Medical College at Thomas Jefferson University

Last full review/revision Mar 2019| Content last modified Mar 2019
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Persistent truncus arteriosus is a birth defect where a single, large blood vessel exits the heart, instead of a separate pulmonary artery and aorta. Deoxygenated blood from the right side of the heart and oxygenated blood from the left side of the heart both enter this single large vessel (the truncus arteriosus) and a mixture of oxygenated and deoxygenated blood then flows to the body and lungs.

  • Symptoms include a bluish coloration of the skin (cyanosis) and symptoms of heart failure, including shortness of breath, poor feeding, sweating, and rapid breathing.

  • Diagnosis is by echocardiography.

  • Medical treatment for heart failure is typically followed by early surgical repair.

When the heart and blood vessels develop in the fetus, at first there is only one large tube, called the truncus, leaving the heart. Normally, the truncus divides into two blood vessels, the pulmonary artery and the aorta (see also Normal Fetal Circulation). Sometimes the truncus does not divide and persists during fetal development and after birth. There is one valve, the truncal valve, leading into this one artery, rather than separate aortic and pulmonic valves.

Persistent truncus arteriosus accounts for 1 to 2% of birth defects of the heart. Nearly all children with persistent truncus arteriosus also have a ventricular septal defect. Other problems that can be associated include a tight or leaky truncal valve, an interrupted aortic arch, a patent ductus arteriosus, an atrial septal defect, and DiGeorge syndrome.

Persistent Truncus Arteriosus

Persistent truncus arteriosus occurs when, during fetal development, the developing truncus does not divide into the pulmonary artery and aorta, resulting in a single, large, blood vessel that exits the heart. As a result, blood that contains oxygen (oxygenated blood) and blood that does not contain oxygen (deoxygenated blood) mix together and enter the body and the lungs.

Persistent Truncus Arteriosus

Symptoms

During the first few weeks of life, infants usually have mild cyanosis (bluish coloration of the skin) and symptoms and signs of heart failure (see figure Heart Failure: Pumping and Filling Problems), including shortness of breath, rapid breathing, poor feeding, and sweating.

Diagnosis

  • Echocardiography

  • Occasionally cardiac catheterization, cardiac magnetic resonance imaging (MRI), or computed tomography (CT) angiography

Diagnosis is suspected based on findings during a doctor's examination of the newborn, including characteristic heart murmurs. A heart murmur is a sound created by turbulent blood flow through narrowed or leaking heart valves or through abnormal heart structures. Findings from chest x-rays and ECG, done when doctors suspect a heart defect, usually provide further clues to the diagnosis. Echocardiography (ultrasonography of the heart) confirms the diagnosis.

Cardiac catheterization, MRI, or CT is occasionally used to identify other coexisting heart problems before surgery.

Treatment

  • Surgical repair

  • Medical treatment of heart failure (eg, diuretics, digoxin, ACE inhibitors) before surgery

Heart failure is treated with drugs to improve breathing until surgery can be done.

Surgery is usually done before the infant is 2 months old. Surgery consists of placement of a patch to repair the ventricular septal defect. Then doctors separate the pulmonary arteries from the truncus and attach them to the right ventricle using a tube (conduits). After this repair, the truncus functions as the aorta.

When a conduit is placed during early infancy, its size becomes inadequate as children grow, and additional surgery is needed to enlarge the conduit. Sometimes the child's own tissue can be used to construct the pathway from the right ventricle to the pulmonary arteries and, in that case, there is the potential for growth as the child grows.

Some children need to take antibiotics before visits to the dentist and before certain surgeries (such as on the respiratory tract). These antibiotics are used to prevent serious heart infections called endocarditis.

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