Incidental noninvasive diagnosis of isolated persistent left superior vena cava in asymptomatic adults

Rationale: Isolated persistent left superior vena cava (IPLSVC) is an extremely rare congenital malformation with a low overall prevalence in the general population. Most patients present without typical clinical manifestations, leading to a relatively high rate of missed diagnoses in clinical practice. Owing to abnormal venous drainage, IPLSVC is frequently complicated with lesions of the cardiac conduction system, which may further induce arrhythmias. Patient concerns: A 37-year-old asymptomatic male patient accidentally discovered IPLSVC through chest echocardiography and computed tomography (CT) scans during a routine physical examination. The patient has no history of cyanosis, breathing difficulties, chest pain, or family history of heart disease. Diagnoses: Transthoracic echocardiography showed coronary sinus dilatation, and chest CT confirmed the absence of the right superior vena cava and the confluence of the right innominate vein into the left superior vena cava. Combined with imaging findings and clinical manifestations, the patient was diagnosed with IPLSVC. Interventions: Complete echocardiography and chest CT were performed to confirm the diagnosis, inform the patient of relevant procedural risks, recommend regular follow-up examinations and ambulatory electrocardiogram monitoring, and retain imaging data for subsequent diagnosis and treatment. Outcomes: The patient experienced no discomfort during follow-up. Regular reexaminations and long-term cardiac monitoring were recommended. Lessons: Although IPLSVC patients are often asymptomatic in the early stages, it may increase the risk of central venous access, cardiothoracic surgery, and pacemaker implantation. Noninvasive echocardiography can provide a basis for early diagnosis of asymptomatic patients and has certain clinical significance. This case helps clinicians further understand IPLSVC in asymptomatic patients, confirms the screening value of routine cardiac ultrasound, and provides practical references for the diagnosis, follow-up, and clinical management of similar cases.