Left Atrial Isomerism in a Four-Year-Old Girl Diagnosed due to Gastrointestinal Bleeding: A Case Report.

Heterotaxy is characterized by the presence of multisystem comorbidities, some of which may result in fatal outcomes. However, diagnosing left atrial isomerism (LAI), a form of heterotaxy, at an early age can be challenging in the absence of typical findings. A four-year-old girl presenting with hypovolemic shock resulting from esophageal variceal bleeding was transported to Saitama Medical Center, Japan, and was diagnosed with LAI post-admission. LAI had not been diagnosed prior to her hospital admission, even though she underwent intracardiac repair for atrioventricular septal defect at 10 months of age. The condition of the patient was characterized by the presence of a duplicated inferior vena cava (IVC), and not by an IVC defect, which is typically associated with LAI. The prevalence of duplicated IVCs in patients with heterotaxy remains unclear. Duplicated IVCs can be detected by abdominal ultrasonography, and an understanding of anatomical variations in the venous pathway may be helpful for the early diagnosis of heterotaxy.