Persistent Left Superior Vena Cava Associating with Anomalous Right Superior Vena Cava Drainage, Atrial Septal Defect, and Atrial Fibrillation: A Case Report
A 53-year-old man presented to the hospital with a history of palpitations, lightheadedness, dyspnea, and chest tightness over the past half month. He also reported a lifelong tendency for activity-induced fatigue and a history of susceptibility to respiratory tract infections. Physical examination revealed an irregular pulse and a cardiac murmur. Auscultation of the pulmonary valve showed an accentuated second heart sound at the left side of the sternum, between the first and second ribs, along with a grade 3/6 systolic murmur. Basic laboratory investigations were unremarkable. An electrocardiogram (ECG) confirmed atrial fibrillation (AF). Chest radiography indicated mild cardiomegaly. Transthoracic echocardiography (TTE) suggested an atrial septal defect (ASD) with a left-to-right shunt, dilation of the left atrium, right atrium, and right ventricle, moderate tricuspid regurgitation, mild pulmonary arterial hypertension, and a markedly dilated coronary sinus due to a persistent left superior vena cava (PLSVC).
To further delineate the venous anomaly and define the location of the shunt, cardiac computed tomography (CT) was performed using a Philips Brilliance 64-slice multidetector CT (MDCT) scanner. The CT confirmed the TTE findings of PLSVC and identified the cardiac shunt as a sinus venosus-type atrial septal defect (SVASD). The right superior vena cava (SVC) was found to drain into the roof of the left atrium. The left-sided persistent SVC was observed draining into the coronary sinus, which was grossly dilated, measuring 3.0 cm. A defect measuring 2.0 cm was noted in the inter-atrial septum. The CT also ruled out other cardiac anomalies commonly associated with PLSVC, such as ventricular septal defect, aortic coarctation, transposition of the great vessels, Tetralogy of Fallot, and anomalous connections of the pulmonary veins. SVASD, if left unrepaired, can lead to right-heart volume overload and subsequent hypertensive pulmonary vascular disease.
The PLSVC drained into the right atrium via the coronary sinus, which has no hemodynamic consequences. However, the right SVC draining directly into the roof of the left atrium can result in a right-to-left shunt or hemodynamic overload on the left atrium, increasing the risk of atrial fibrillation or paradoxical embolization. Therefore, surgical intervention was recommended. The surgical procedure involved opening the right heart chamber and draining the PLSVC using a separate venous cannula. The modified Cox-Maze AF surgical procedure was performed concomitantly with the SVASD repair. A surgical patch was used to repair the SVASD and isolate the opening of the right SVC to the right atrium. The PLSVC was not ligated.
PLSVC is the most common anomaly of the thoracic venous system, occurring in approximately 0.5% of the general population. It results from the failed regression of the left anterior cardinal vein, which typically forms the Marshall ligament. In 80%–90% of cases, PLSVC coexists with a right SVC. In instances of bilateral SVCs, a left innominate vein may be completely absent in approximately 65% of cases. In 80%–92% of PLSVC cases, the PLSVC drains into the right atrium through the coronary sinus, causing no hemodynamic consequences. Conversely, in 10%–20% of cases, the PLSVC can drain into the left atrium through an unroofed coronary sinus, the left superior pulmonary vein, or directly into the roof of the left atrium. In cases of bilateral SVCs, the right SVC typically drains normally into the right atrium. However, the right SVC draining into the roof of the left atrium, as observed in this patient, is very rare. PLSVC is usually asymptomatic and is often an incidental finding on imaging.
In approximately 0.3%–0.5% of cases, PLSVC coexists with congenital heart disease (CHD). During the diagnostic procedure for this patient, SVASD was identified. ASD develops due to the absence or maldevelopment of the atrial infolding that normally separates the two atria. SVASD accounts for 5%–10% of all ASDs and is located along the superior aspect of the atrial septum, near the entry of the right SVC. SVASD may be asymptomatic in childhood but can become symptomatic with age. Unrepaired SVASD can lead to right heart volume overload and eventually hypertensive pulmonary vascular disease. Therefore, surgical repair of SVASD was performed once the diagnosis was made. The association of PLSVC and SVASD is very rare in the reported literature.
PLSVC has practical implications for procedures such as permanent pacemaker placement, implantable cardioverter defibrillator placement, and right-heart catheterization. Serious complications, including arrhythmia, cardiogenic shock, cardiac tamponade, and coronary sinus thrombosis, have been reported when pacemaker leads or catheters are inserted via PLSVC. It is critical to confirm the presence of PLSVC, fully characterize the pattern of cardiac venous return, and identify other potential coexisting congenital heart abnormalities before initiating the use of central venous access devices and thoracic surgery. TTE, transesophageal echocardiography (TEE), and cardiac CT can be used to assess PLSVC and potential coexisting congenital cardiac malformations.
Atrial arrhythmias (AAs), including AF and/or flutter (AFL), are significantly increased in patients with ASDs. The left-to-right shunt enabled by the presence of an ASD results in cardiac remodeling secondary to long-standing hemodynamic overload. This geometrical remodeling plays a vital role in the pathogenesis of AAs. The presence of AAs should be considered an indication for closure of an ASD. Surgeons may perform an AF surgical procedure, such as the modified Cox-Maze procedure, prior to the surgical repair of ASDs. Although AAs may not revert to sinus rhythm after the combination of the two surgical procedures, they are likely to improve mortality and symptoms.
In conclusion, this case highlights the rare association of PLSVC with anomalous right SVC drainage, SVASD, and AF. The patient underwent successful surgical repair of the SVASD and the modified Cox-Maze procedure for AF. The presence of PLSVC and its associated anomalies underscores the importance of thorough diagnostic imaging and careful surgical planning to address the complex hemodynamic and arrhythmic issues in such cases.
doi.org/10.1097/CM9.0000000000000044
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