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Truncus arteriosus

Definition

Truncus arteriosus is a rare type of congenital heart disease in which a single blood vessel (truncus arteriosus) comes out of the right and left ventricles, instead of the normal two (pulmonary artery and aorta).

There are different types of truncus arteriosus, depending on the anatomy of the single vessel.

Alternative Names

Truncus

Causes, incidence, and risk factors

In normal circulation, the pulmonary artery comes out of the right ventricle and the aorta comes out of the left ventricle, which are separate from each other. Coronary arteries (which supply blood to the heart muscle) come out of the aorta just above the valve at the entrance of the aorta.

In truncus arteriosus, a single artery comes out of the ventricles. There is usually also a large hole between the two ventricles (ventricular septal defect). As a result, the blue (without oxygen) and red (oxygen-rich) blood mix.

Some of this mixed blood goes to the lungs, some goes to the coronary arteries, and the rest goes to the body. Usually, too much blood is sent to the lungs.

If left untreated, two problems occur:

• Too much blood circulation in the lungs may cause extra fluid to build up in and around them, making it difficult to breathe.
• The blood vessels to the lungs become permanently damaged. Over time, it becomes very hard for the heart to force blood to them. This is called pulmonary hypertension and it can be life-threatening.

Symptoms

• Bluish skin (cyanosis)
• Delayed growth or growth failure
• Fatigue
• Lethargy
• Poor feeding
• Rapid breathing (tachypnea)
• Shortness of breath (dyspnea)
• Widening of the finger tips (clubbing)

Signs and tests

A murmur is usually heard when listening to the heart with a stethoscope.

Tests include:

• ECG
• Echocardiogram
• Heart catheterization (only needed in rare cases to help with the diagnosis or in planning a treatment strategy)
• MRI of the heart
• X-ray of the chest

Treatment

Surgery is needed to treat this condition. Two procedures are available.

One treatment involves banding the pulmonary arteries coming off the truncus to limit the amount of blood that can flow through them. However, this procedure is rarely used anymore.

The other procedure is called complete repair. Complete repair appears to be the preferred option.

Support Groups

Expectations (prognosis)

Complete repair usually provides good results. Another procedure may be needed as the patient grows. Untreated cases result in death, often during the first year of life.

Complications

• Heart failure
• High blood pressure in the lungs (pulmonary hypertension) with pulmonary obstructive lung disease

Calling your health care provider

Call your health care provider if your infant or child:

• Appears lethargic
• Appears overly tired or mildly short of breath
• Does not eat well
• Does not seem to be growing or developing normally

If the skin, lips, or nail beds look blue or if the child seems to be very short of breath, take the child to the emergency room or have the child examined promptly.

Prevention

There is no known prevention, but early treatment can often prevent serious complications.

References

Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th ed. St. Louis, Mo; WB Saunders; 2007.