Conclusion
Congenital heart disease with LSVC should be aware of the presence of UCSS. Preoperative TTE is still the main method to diagnose UCSS, and it can improve the diagnostic rate of TTE to strengthen the understanding of the pathologic anatomy and pathophysiological characteristics of this cardiac malformations. According to the location of LSVC into the LA, different surgical methods were selected, and satisfactory results were achieved. The mortality rate of this series of patients was 3.1% (5/159), the cause of death mainly depends on the complexity and severity of the associated cardiac malformations.