Makindo Medical Notes

💔 Truncus Arteriosus is a rare congenital heart defect where a single common arterial trunk arises from the heart, giving rise to systemic, pulmonary, and coronary circulations. This results in mixing of oxygenated and deoxygenated blood, causing cyanosis and heart failure if untreated.

📌 About

• A single large blood vessel replaces the normal pulmonary artery and aorta.
• Almost always associated with a ventricular septal defect (VSD).
• Mixed circulation → oxygen-poor and oxygen-rich blood flow together to the lungs and body.
• Accounts for ~1% of congenital heart disease.

🧾 Aetiology

• Failure of embryonic truncus arteriosus septation into separate aortic and pulmonary outflow tracts.
• Often associated with 22q11 deletion (DiGeorge syndrome).
• Other genetic or sporadic mutations may contribute.

🧑‍⚕️ Clinical Features

• 💙 Central cyanosis (due to blood mixing).
• 😮‍💨 Tachypnoea, respiratory distress.
• 🍽️ Poor feeding and failure to thrive.
• 🫀 Bounding pulses, tachycardia, cardiomegaly.
• 🛌 Lethargy and recurrent chest infections.

🔍 Investigations

• 🩻 CXR: Cardiomegaly, increased pulmonary vascular markings.
• 📈 ECG: Biventricular hypertrophy.
• 🫀 Echocardiography: Diagnostic; shows single arterial trunk overriding a VSD.
• 🧬 Consider genetic testing (22q11 deletion).

🧫 Pathology

• Failure of conotruncal ridges to fuse during embryogenesis.
• Common arterial trunk gives rise to coronary, systemic, and pulmonary arteries.
• Increased pulmonary blood flow → early pulmonary hypertension.

🛠️ Management

• ⚡ Stabilisation: Diuretics and inotropes for heart failure symptoms.
• 💉 Prostaglandin infusion may be used to maintain ductal patency in unstable infants.
• 🔧 Surgical repair:
  • Closure of the VSD.
  • Separation of pulmonary arteries from the truncus.
  • Placement of a conduit from right ventricle to pulmonary arteries.
• 📅 Surgery usually performed in the first few months of life.
• 👶 Lifelong cardiology follow-up required; conduits often need replacement as the child grows.

📚 References

• CDC – Truncus Arteriosus