RESUMEN
We present the case of a fetus with cardiac capillary hemangioma in the right atrial cavity. The tumor showed dramatic growth between the 28th and 32nd week of gestation and resulted in tachyarrhythmia. The patient was born at the 33 weeks of gestation weighing 2430 g via urgent cesarean section because the rapidly growing cardiac tumor caused incessant tachyarrhythmia, pericardial effusion, and fetal circulatory incompetence. Coronary angiography revealed that the right coronary artery drained into the tumor. Due to hemodynamic deterioration, the patient underwent subtotal resection of the tumor on the 2nd day after birth. Histopathological examination revealed an undifferentiated capillary hemangioma. The patient was discharged at the age of 86 days, as the tachyarrhythmia and hemodynamic incompetence had subsided; however, bradycardia and intermittent atrioventricular conduction disturbance gradually developed. Capillary hemangioma, a rare primary cardiac space-occupying tumor in children, can invade the conduction system.