We present a case of a neonatal interventricular septal aneurysm associated with right coronary artery fistula. A male fetus diagnosed with right coronary artery fistula and interventricular septal aneurysm by fetal echocardiography was delivered via elective caesarean section at 38 weeks (birth weight 2916 g) to prevent sudden cardiopulmonary collapse due to coronary steal. Postnatal echocardiography (Figure 1a and b) and contrast-enhanced CT (Figure 2a–c) confirmed the diagnoses. The dilated right coronary artery drained into the aneurysm, which then drained into the right ventricle.

Figure 1. Preoperative echocardiography. (a) Apical four-chamber view. (b) Short-axis view. An = interventricular septal aneurysm; RV = Right Ventricle; LV = Left Ventricle; dRCA = Dilated Right Coronary Artery; CAF = Coronary Artery Fistula.

Figure 2. Preoperative contrast-enhanced CT. ( a ) Axial view. ( b ) Anterior view of 3D-contrast-enhanced CT: the origin and course of the dRCA is normal. The white arrow indicates the origin of the dRCA. (c) Posterior view of 3D-contrast-enhanced CT = the dRCA drains into the aneurysm, which then drains into the RV. An = Interventricular Septal Aneurysm; RV = right ventricle; LV = Left Ventricle; dRCA = Dilated Right Coronary Artery; CAF = Coronary Artery Fistula.

Despite no signs of myocardial ischaemia, we opted for surgical intervention immediately after birth to avoid potential myocardial ischaemia from a physiological decrease in pulmonary arterial pressure. Using cardiopulmonary bypass, antegrade cardioplegia was infused into the aortic root while compressing the peripheral end of the dilated right coronary artery. We longitudinally incised the peripheral end of the right coronary artery and found a foramen connecting to the interventricular septum. We directly closed it by interrupted sutures. The dilated right coronary artery was closed using continuous suture.

Postoperative echocardiography before discharge showed partial regression of the aneurysm (Figure 3a), and angiography one year later confirmed complete regression of the aneurysm and an intact right coronary artery (Figure 3b). This suggests the aneurysm was the ventricular exit of the coronary fistula, as its remodelling and regression indicate it was likely fistulous.

Figure 3. Postoperative images. ( a ) Echocardiography (postoperative day 43): The aneurysm is partially regressed. ( b ) Angiography (one year after surgery): The aneurysm is completely regressed, and the RCA is intact. An = Interventricular Septal Aneurysm; RCA = Right Coronary Artery.

Although adult cases are reported, ^{Reference Zhi Ku, Xia, Lv, Song and Ma1} this is the first report of a neonatal coronary artery fistula-associated intraventricular septal aneurysm, highlighting the importance of early diagnosis and surgery.