Disease Description (Causes and Symptoms)
- Definition: Truncus arteriosus is a congenital heart defect in which one large blood vessel (the truncus arteriosus), which should divide into the aorta and pulmonary artery during fetal development, remains undivided. It is usually accompanied by a ventricular septal defect (VSD).
- Pathophysiology: Blood from the left and right ventricles flows into one common artery, causing the loss of oxygen separation and excessive pulmonary blood flow, which leads to pulmonary vascular hypertension and heart failure. If treatment is delayed, increased pulmonary vascular resistance (Eisenmenger reaction) makes surgical correction difficult.
- Main causes (reflecting priority RAG information): The cause is unknown in most cases, but possible genetic predisposition (family history), rubella infection during pregnancy, and fetal exposure to alcohol or antiepileptic drugs (e.g., phenytoin) are risk factors. It may be associated with conditions such as DiGeorge syndrome (22q11 deletion), so chromosomal and genetic testing is recommended.
- Main symptoms: Severe cyanosis in the neonatal period (reduced oxygen saturation), difficulty breathing, feeding difficulty, growth retardation, tachycardia (bounding pulse), myocardial hypertrophy, and signs of congestive heart failure. Abnormalities of the truncal valve (regurgitation or stenosis) may be present in 25–50% of cases.
Treatment Methods
- Basic principles: Complete corrective surgery as early as possible (ideally at 1–2 months of age, in principle within 3 months of age, and no later than 6 months of age) is the standard treatment. Delayed treatment increases surgical risk due to rising pulmonary vascular resistance.
- Surgical treatment (standard)
- Complete repair (Rastelli-type):
- Use a patch to separate the origins of the aorta and pulmonary artery from the common artery
- Close the ventricular septal defect with a patch to direct blood flow from the left ventricle to the aorta
- Insert a valved conduit or homograft valve connecting the right ventricle and pulmonary artery
- Perform truncal valve repair (valvuloplasty) when necessary
- Pulmonary artery banding: When complete repair is not immediately possible (e.g., due to anatomical constraints or severe underlying systemic illness), restrict pulmonary blood flow to prevent pulmonary vascular damage and prepare for complete repair after growth.
- Complete repair (Rastelli-type):
- Drug treatment (preoperative and conservative treatment)
- For infants with symptoms of congestive heart failure, temporary stabilization may be attempted with diuretics, digitalis-type drugs, or other heart-failure supportive medications.
- Oxygen support and nutritional support (high-calorie feeding, tube feeding, etc.).
- General treatment for infection and emergencies immediately before or after surgery.
- Postoperative and long-term management
- The inserted artificial conduit or homograft valve does not grow, so repeat surgery (replacement) will be needed in the future. Homograft valves may develop stenosis or regurgitation due to calcification and valve degeneration, and replacement may be necessary.
- Regular echocardiography and electrocardiography, and when necessary cardiac catheterization and cardiovascular angiography, are used to monitor function and complications (residual shunts, valve regurgitation/stenosis, left and right ventricular function, etc.).
- Whether prophylactic antibiotics should be used when there is a risk of infective endocarditis during oral or dental procedures should be determined according to the treating physician's guidance.
- Precautions (risk of complications)
- Delayed surgery may lead to irreversible pulmonary vascular disease (Eisenmenger syndrome) due to increased pulmonary vascular resistance.
- Repeat surgery (valve/conduit replacement), valve regurgitation or stenosis, residual VSD, heart failure, and arrhythmias may occur.
- Comprehensive evaluation for associated abnormalities (e.g., DiGeorge syndrome and aortic arch abnormalities) is necessary.
Checklist Before an Outpatient Visit (Including Sample Questions)
- Items to prepare
- List of currently used medications (including dosage and administration times)
- Birth/neonatal history and current weight and growth-curve records
- Copies of previous echocardiography, electrocardiography, cardiac catheterization, and angiography results (image files if possible)
- Surgical history (if surgery was previously performed, operative notes and information about implanted devices)
- Family history and genetic test results (if available)
- Record of recent symptom changes (worsening cyanosis, difficulty breathing, feeding difficulty, fever, etc.)
- Items to check in advance at the outpatient visit
- Oxygen saturation, whether weight is increasing, changes in breath and heart sounds, and medication adherence
- Sample questions (questions for the patient/guardian)
- How have feeding and weight gain been recently?
- Have the frequency or pattern of cyanosis or difficulty breathing changed?
- What were the valve and thoracic anatomical findings on previous test results (such as echocardiography)?
General Sample Questions to Ask the Doctor
- What is the optimal recommended timing for surgery in this condition?
- What are the expected benefits of surgery and the major risks of complications?
- What medications are needed before and after surgery, and what are their side effects?
- What is the long-term prognosis (through adulthood), and how likely is repeat surgery or an additional procedure to be needed?
- Are additional tests (e.g., 22q11 testing) needed because another abnormality or genetic problem is suspected?
Disease-Specific Sample Questions
- Please explain the condition of the truncal valve in detail. How does the degree of valve regurgitation or stenosis affect the surgical plan?
- Are the anatomy of the pulmonary artery branches (the left and right pulmonary arteries) and the pulmonary vascular resistance (pulmonary artery pressure) currently suitable for surgery? Should pulmonary artery banding be considered if necessary?