Large aneurysm of the right atrial and the tetralogy of fallot: a rare case report and literature review

Introduction Congenital right atrial (RA) aneurysm is a rare cardiac anomaly, and its association with complex cyanotic heart disease, such as tetralogy of Fallot (TOF), is exceptionally uncommon. This combination poses significant diagnostic and therapeutic challenges. Case presentation We report the case of a 22-month-old boy with uncorrected TOF who was found to have a giant RA aneurysm (approximately 3 × 5 cm) causing significant compression of the left ventricle. The diagnosis was confirmed by transthoracic echocardiography and computed tomography angiography. The patient underwent complete single-stage surgical repair, including TOF correction (ventricular septal defect closure and right ventricular outflow tract reconstruction) and RA aneurysmectomy with patch closure of a large communication between the RA and the aneurysmal sac. Outcome Despite a technically successful operation, the patient developed catastrophic hemodynamic collapse several hours postoperatively and could not be resuscitated. Post-mortem examination revealed re-expansion of the aneurysm with thrombus within the pericardial space, adjacent to the left ventricle. While the exact mechanism of hemodynamic collapse remains uncertain, the post-mortem findings suggest that the distended aneurysmal sac may have contributed to impaired cardiac filling or reduced ventricular preload. We hypothesize that residual vascular communications to the aneurymal cavity may have contributed to this fatal complication. Conclusion This case highlights a rare and fatal association between a giant RA aneurysm and TOF. It underscores the critical importance of meticulous intraoperative evaluation for potential coronary-cameral fistulae or additional venous drainage into the aneurysmal sac. We recommend direct intraoperative testing, such as cardioplegic injection, to identify and ligate these vessels, which may be crucial for preventing fatal postoperative re-expansion in similar cases.