Persistent left superior vena cava associating with anomalous right superior vena cava drainage, atrial septal defect and atrial fibrillation: a case report

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Persistent left superior vena cava associating with anomalous right superior vena cava drainage, atrial septal defect and atrial fibrillation: a case report

Most people have one main vein—the right superior vena cava (SVC)—carrying blood from the upper body to the heart. But in rare cases, a leftover vein from fetal development called the persistent left superior vena cava (PLSVC) remains. While usually harmless, PLSVC can become problematic when paired with other heart defects. A recent case from China illustrates how these combined anomalies can cause symptoms and require careful surgical management.

Lei Li, Ke-Qiang Ji, and Chun-Yuan You from the Affiliated Wuxi No. 2 People’s Hospital of Nanjing Medical University (Jiangsu, China) described the case of a 53-year-old man who arrived at their hospital with a two-week history of palpitations, lightheadedness, shortness of breath, and chest tightness. Since childhood, he’d felt tired with activity and often got respiratory infections—clues that something was amiss with his heart.

During a physical exam, doctors found an irregular pulse (a sign of atrial fibrillation, or AF) and a heart murmur. Listening to his chest, they heard an accentuated second heart sound near the pulmonary valve (a sign of increased pressure in the lungs) and a grade 3/6 systolic murmur (a medium-loud sound from blood flow through a hole or leaky valve). Basic blood tests were normal, but an electrocardiogram (ECG) confirmed AF, and a chest X-ray showed mild heart enlargement.

A transthoracic echocardiogram (TTE)—an ultrasound of the heart—revealed several issues: a left-to-right shunt through an atrial septal defect (ASD, a hole in the wall between the heart’s upper chambers), dilated left and right atria and right ventricle, moderate tricuspid valve regurgitation, mild pulmonary hypertension, and a very enlarged coronary sinus (the vein that collects blood from the heart muscle). The coronary sinus dilation pointed to PLSVC, since this vein typically drains into the coronary sinus.

To get a clearer picture, doctors used a 64-slice cardiac computed tomography (CT) scanner. The CT confirmed PLSVC draining into the coronary sinus (measuring 3 cm wide) and identified the ASD as a “sinus venosus-type” (SVASD)—a rare type (5-10% of ASDs) located near where the right SVC enters the right atrium. Crucially, the CT showed the right SVC was draining directly into the roof of the left atrium—a very unusual finding. It also ruled out more common heart defects linked to PLSVC, like ventricular septal defects or abnormal pulmonary vein connections.

Why did this matter? SVASD, if untreated, causes the right heart to work too hard (volume overload) and can lead to high blood pressure in the lungs. The anomalous right SVC drainage added another problem: blood from the upper body was going into the left atrium instead of the right, overloading the left atrium and increasing the risk of AF or “paradoxical embolism” (a blood clot traveling from the right side of the heart to the left, then to the brain or other organs). The PLSVC itself was harmless (it drained to the right atrium via the coronary sinus), but the combination of issues required surgery.

During surgery, doctors opened the right heart and used a separate cannula to drain the PLSVC (since standard heart-lung machine tubes might not handle bilateral SVCs). They repaired the SVASD with a patch and redirected the right SVC opening to the right atrium—fixing both the hole and the abnormal drainage. They also performed a modified Cox-Maze procedure (a surgical treatment for AF that creates scar tissue to block irregular electrical signals) at the same time. The PLSVC was left intact because it didn’t cause hemodynamic problems.

PLSVC is the most common thoracic vein anomaly, affecting about 0.5% of people. It forms when the left anterior cardinal vein—one of two veins that carry blood from the upper body in fetuses—fails to disappear (normally, it shrinks into a small ligament). In 80-90% of cases, PLSVC coexists with a normal right SVC, and 65% of these people lack a left innominate vein (the vein that connects the left and right SVCs). Most PLSVCs (80-92%) drain safely into the right atrium via the coronary sinus. Only 10-20% drain into the left atrium—usually through an unroofed coronary sinus or abnormal connections to the pulmonary veins.

What makes this case rare is the combination of PLSVC, anomalous right SVC drainage, SVASD, and AF. While PLSVC often goes unnoticed, it can complicate procedures like pacemaker placement or right-heart catheterization. Inserting devices through PLSVC has caused serious issues like arrhythmias, heart shock, or blood clots in the coronary sinus. That’s why pre-op imaging (TTE, CT, or transesophageal echocardiography) is critical to map vein anatomy and check for other defects.

AF is common in people with ASDs because the left-to-right shunt stretches and remodels the heart’s chambers over time. This remodeling creates a “substrate” for irregular electrical signals—exactly what happened in this patient. Fixing the ASD alone isn’t enough; combining it with an AF procedure (like the Cox-Maze) improves symptoms and survival, even if AF doesn’t fully go away.

The patient’s surgery was successful, and the case highlights two key points: first, rare vein anomalies can hide alongside other heart defects, so thorough imaging is essential. Second, treating multiple issues (like SVASD and AF) together can address both the structural and electrical problems causing symptoms.

The authors confirmed they had the patient’s consent to publish his case, and they reported no conflicts of interest.

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Li L, Ji KQ, You CY. Persistent left superior vena cava associating with anomalous right superior vena cava drainage, atrial septal defect and atrial fibrillation: a case report. Chin Med J 2019;132:220–222. doi.org/10.1097/CM9.0000000000000044

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