17 Common Arterial Trunk or Truncus Arteriosus
A 33-year-old white woman, gravida 4, para 3+0, with DiGeorge’s syndrome was referred at 25 weeks’ gestation by her obstetrician for fetal echocardiogram, given the autosomal dominance of her condition. She had had an otherwise uncomplicated pregnancy. She has two other children, one normal and one with suspected DiGeorge’s syndrome.
b. Development of hydrops fetalis secondary to congestive heart failure (CHF) is unlikely (approximately 5% risk for all types of congenital heart disease (CHD)), but it could occur if there is progressive truncal valve regurgitation or stenosis.
1. In classic truncus without any signs of heart failure, aortic interruption, or other associated malformation, delivery should be as close to term as possible and in an institution with at least neonatal intensive care support.
d. Administration of oxygen is usually contraindicated in this disease in the absence of significant pulmonary pathology because it decreases the pulmonary vascular resistance, which would increase pulmonary blood flow further.
e. Given the presence of 22q11.2 microdeletion, the infant will need assessment of T-cell subsets and serum calcium levels. Affected infants often require calcium supplements. Given the potential for immunocompromise, CMV-negative and irradiated blood is critical.
a. Complete correction of common arterial trunk of this type is usually performed in the first 4 to 6 weeks of life. Waiting later than this places the baby at risk for significant pulmonary hypertension.
b. Correction includes closing the VSD, leaving the LV in continuity with the truncal valve, and placing a valved RV–to–pulmonary artery conduit (usually a homograft). The surgeon should attempt to repair the truncal valve, if necessary.
d. Timing of the operation varies by institution but is generally performed electively at 1 to 3 months of age. Earlier corrective repair may be necessary in a baby with severe heart failure or coronary artery steal.