Discussion

Truncus arteriosus, also known as common arterial trunk, is an uncommon (1–3% of all cases of congenital heart disease) congenital cardiac defect that presents at birth. ^{Reference Russell, Pasquali and Jacobs1} It supplies blood to the systemic and pulmonary circulation simultaneously, leading to increased pulmonary circulation and congestive heart failure. Within a few weeks after birth, the pulmonary hypertension will significantly increase, even leading to a pulmonary hypertension crisis after operation. Mayo Clinic’s early experience also showed that early mortality was associated with increased pulmonary vascular resistance. Currently, the surgical treatment of truncus arteriosus is generally advocated in neonates or within 3 months after birth to reduce the incidence of pulmonary hypertension crisis. ^{Reference Marcelletti, McGoon and Mair2} In this case, the patient was 16-month-old, so the cardiac catheterization was performed to exclude the surgical contraindication.

Anomalies of the coronary arteries found in approximately 5–20% of truncus arteriosus patients ^{Reference Lenox, Debich and Zuberbuhler3} and has been associated with high mortality following truncus arteriosus repair. ^{Reference Naimo, Fricke and Yong4} The coronary artery pattern in truncus arteriosus should be determined preoperatively. Naimo et al made a retrospective study of 171 children who underwent truncus arteriosus repair, which demonstrated that a coronary artery anomaly carries a significant risk of death after repair of truncus arteriosus. ^{Reference Naimo, Fricke and Yong4} Bonilla-Ramirez and colleagues concluded 34 patients with coronary lesion in 107 with truncus arteriosus. Four coronary lesions were identified: single coronary artery, ostial stenosis, intramural course, and juxtacommissural origin. Patients with complex coronary lesions have poor survival. ^{Reference Bonilla-Ramirez, Ibarra and Binsalamah5}

The origin of a single coronary artery outside aortic sinuses or above the aortic valve cusps is extremely uncommon. There are few reported cases of a single coronary artery arising from the innominate artery with additional truncus arteriosus and single ventricle malformations which were diagnosed at necropsy. Liu et al ^{Reference Liu, Huang and Zhang6} in 2010 reported the case of a 42-day-old infant-boy with anomalous origin of a single coronary artery from the right branchiocephalic trunk associated with hypoplastic left ventricle, mitral atresia, and truncus arteriosus. Due to the poor prognosis and challenging surgery, the boy did not receive operation.

In our case of truncus arteriosus, a single coronary arose from a much higher site on the innominate artery. It would have been hard to perform coronary artery bypass grafting for such a small infant. We did not try to perform coronary reimplantation because the coronary button was difficult to procure, and the adequate location for reimplantation was difficult to select. Moreover, no specific surgical technique has been used in cases with a high take-off coronary artery and frequently required reoperation due to coronary artery stenosis. ^{Reference Jung, Kwak and Kim7} Although we performed preoperative cardiac catheterization for this patient, the anomalies of the coronary arteries were not found as coronary angiography was too dangerous to be performed on the infant. Not having CT angiography images for this special patient is a regret. Due to the existing coronary artery fistula, the cardiac arrest could not be obtained successfully. It is important to select the location where cardioplegia infusion needle is inserted. Careful observation is needed when cardioplegia solution is infused.

There may be a connection between a single coronary artery arising from the innominate artery and truncus arteriosus according to the literature reports. The cardiac surgeon must be aware of the abnormal anatomy to avoid accidental ligation or cross-clamping or transection of the anomalous coronary artery during surgery. The three defects described above are rarely found together, and we performed successful surgical treatment; indeed, such a case as ours may be the first reported in the literature.