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Truncus arteriosus is a congenital heart defect, meaning it is present from birth. In this condition, a baby’s heart has a single large artery instead of the usual two, which leads to the mixing of oxygen-poor and oxygen-rich blood. This mixing reduces the oxygen supply to the body and increases blood flow to the lungs, placing extra strain on the heart.
Typically, individuals with truncus arteriosus also have a hole between the lower chambers of the heart, known as ventricles, referred to as a ventricular septal defect. Another term for truncus arteriosus is common arterial trunk.
Truncus arteriosus is a life-threatening condition, necessitating surgical intervention to correct the heart abnormalities and restore proper blood flow. Successful surgery is often achievable, especially when performed within the first month of a baby’s life.
Symptoms
Symptoms of truncus arteriosus typically manifest within the first few days after birth and may include:
- Bluish or grayish skin color due to decreased oxygen levels.
- Poor weight gain.
- Inadequate feeding.
- Excessive drowsiness.
- Noticeably strong or rapid heartbeat.
- Rapid breathing.
- Difficulty in breathing.
It is essential to consult a healthcare professional if you have concerns about your baby’s feeding habits, sleep patterns, or growth.
However, immediate medical attention is crucial if your baby experiences:
- Bluish or grayish skin.
- Rapid breathing.
- Shallow breathing.
- Any signs of breathing distress.
Causes
Truncus arteriosus is a congenital heart defect that arises during fetal development, often with no clear cause, and it may be influenced by genetic and environmental factors. In a typical heart, there are four chambers responsible for specific functions: the right atrium receives oxygen-poor blood from the body, the right ventricle pumps blood into the lungs to receive oxygen, the left atrium receives oxygen-rich blood from the lungs, and the left ventricle pumps oxygenated blood throughout the body via the aorta.
Truncus arteriosus is characterized by the failure of the single large blood vessel (truncus) to divide into the pulmonary artery and aorta as it normally should during fetal development, resulting in a condition known as ventricular septal defect (VSD). Although the precise causes are still under investigation, genetics are thought to be a contributing factor, with certain gene changes potentially playing a role in this defect’s development. It’s worth noting that roughly one in three children with truncus arteriosus also have DiGeorge syndrome, a chromosomal disorder associated with heart defects, immune system issues, and developmental delays.
Risk factors
The precise cause of truncus arteriosus remains unclear, but several factors can elevate the risk of a congenital heart problem at birth. These risk factors encompass:
- Viral illness during pregnancy: Infections contracted during pregnancy, such as German measles (rubella), can adversely affect the developing baby’s heart development.
- Poorly managed diabetes during pregnancy: Maintaining strict control of blood sugar levels before and during pregnancy can lower the likelihood of heart problems in the baby. It is crucial for individuals with diabetes to collaborate closely with their healthcare provider to ensure optimal blood sugar control before conceiving.
- Use of specific medications during pregnancy: Certain medications can lead to heart problems and other health issues in the baby. It is essential to inform your healthcare provider about all medications you are taking, including over-the-counter drugs.
- Chromosomal disorders: The presence of an extra or irregular chromosome heightens the risk of truncus arteriosus. Examples of such disorders include DiGeorge syndrome (22q11.2 deletion syndrome) and velocardiofacial syndrome.
- Smoking during pregnancy: Quitting smoking is strongly advised if you are a smoker. Smoking during pregnancy increases the baby’s risk of developing heart problems.
- Alcohol consumption: Drinking alcohol during pregnancy is associated with an increased risk of heart problems and other health conditions in the baby.
- Overweight: Being obese during pregnancy raises the likelihood of giving birth to a baby with a heart problem.
It is important for expectant mothers to be aware of these risk factors and take necessary precautions to ensure the health and well-being of their unborn child.
Diagnosis
Truncus arteriosus is often diagnosed shortly after a child’s birth, with affected newborns displaying bluish or grayish skin color and respiratory issues. During the initial medical assessment, healthcare professionals routinely evaluate the baby’s lung function through auscultation of their breath sounds. In cases of truncus arteriosus, healthcare providers may identify abnormal lung sounds suggesting fluid retention. Furthermore, they listen to the baby’s heart to detect irregular heartbeats and the characteristic whooshing sound known as a murmur.
To confirm the diagnosis of truncus arteriosus, several tests are performed:
- Pulse oximetry: This involves placing a sensor on the baby’s fingertip to measure the oxygen levels in the blood. Low oxygen levels may suggest a heart or lung problem.
- Chest X-ray: This diagnostic imaging test provides insights into the condition of the heart and lungs, allowing for an assessment of heart size and the presence of excess fluid in the lungs.
- Echocardiogram: The primary diagnostic tool for truncus arteriosus, an echocardiogram employs sound waves to generate images of the functioning heart. In cases of truncus arteriosus, the test reveals a single, large vessel emerging from the heart and often identifies a hole in the wall that separates the lower heart chambers.
Treatment
Infants born with truncus arteriosus require surgery to improve their blood flow and oxygen levels. Additional procedures or surgeries may be necessary as the child grows, and medications may be prescribed before surgery to support heart health.
Medications
- Water pills (diuretics): Are given to help the kidneys remove excess fluid from the body, which is a common symptom of heart failure.
- Positive inotropes: Are used to strengthen the heart’s pumping ability, improving blood flow and blood pressure control. They may be administered intravenously in cases of severe heart failure.
Surgery and procedures
Most infants with truncus arteriosus undergo surgery within the first few weeks of life, with the specific procedure tailored to the baby’s condition.
The surgeon typically:
- Rebuilds the single large vessel and aorta to create a new, complete aorta.
- Separates the upper part of the pulmonary artery from the single large vessel.
- Uses a patch to close the hole between the two lower heart chambers.
- Places a tube and valve to connect the right lower heart chamber with the upper pulmonary artery, forming a new, complete pulmonary artery.
It’s important to note that the tube used to create the new pulmonary artery does not grow with the child, necessitating follow-up surgeries to replace it as the child grows.
In the future, some of these surgeries may be performed using a flexible catheter instead of open-heart surgery. This involves inserting a catheter into a blood vessel in the groin and guiding it to the heart, where a new valve can be delivered to the appropriate location. This approach can also include balloon angioplasty, where a small balloon is inflated to widen a blocked artery.
After truncus arteriosus surgery, lifelong follow-up care with a congenital cardiologist, a heart doctor specializing in congenital heart diseases, is essential.
