PLSVC has an estimated incidence of 0.3-0.5%. 4PLSVC occurs due to the failure of involution of the left cardinal vein during the foetal life. It is rarely reported as most of the dialysis catheters are inserted through the right IJV and PLSVC co-exists with the right SVC in> 80% of patients.5,6 PLSVC should be considered especially when the CVC via the left subclavian vein or IJV proved to be difficult. It may be associated with other congenital cardiac anomalies such as atrial septal defect (ASD), ventricular septal defect (VSD) or atrioventricular septal defect.7 In this case, there was no evidence of cardiac anomalies as evidenced by the TTE. In general, it is normally cause no symptoms and hemodynamically insignificant.8,9PLSVC is typically detected incidentally during procedures such as hemodialysis catheter placement. Ultimately, it can potentially lead to many serious complications such as systemic embolization, provocation of arrhythmia, vascular thrombosis, shock , angina and cardiac arrest.2
LSVC may appear on the posteroanterior chest radiograph where it manifest itself as widening of the aortic shadow, paramedian stripe, paramediastinal bulging or as a low density line along the upper left margin of the heart.10
It can be diagnosed non-invasively by echocardiography on conjunction with doppler and/or contrast ultrasonography. Other diagnostic modalities include Ct scan and MRI.11
Lim et al reported a similar case when they performed the procedure under fluoroscopy. They initially thought it was an arterial puncture; however, they proceeded with the insertion of the catheter after confirming a venous puncture. A digital subtraction angiography revealed the PLSVC, and the patient was hemodialysed using the catheter for five months without any complications 7.Jang et al described another case when they had to insert a left sided temporary dual lumen catheter for a patient with fistula failure, and the chest radiograph showed that the catheter tip was on the left paramediastinal side (similar to our case).8 They did not remove the catheter immediately, instead they confirmed the location of the catheter by CT scan and the diagnosis of PLSVC was made. Stylianou et al reported another case of PLSVC which was incidentally diagnosed after the placement of the hemodialysis catheter through the left internal jugular vein.12 The chest radiograph showed the abnormal position of the catheter tip in the left paramediastinal area. They proceeded to CT scan and transthoracic echocardiogram to confirm the diagnosis. The catheter was used for dialysis for a month before she was able to proceed using the newly fashioned graft.
With the rise of ESRD patients on hemodialysis in Malaysia, it is essential for the clinicians who insert central venous catheters (CVC) to be aware of this congenital anomaly in order to prevent further complications. Moreover, it is vital to exclude other concomitant cardiac anomalies such as septal defects so as to prevent systemic embolism following thrombosis of the CVC.
LEARNING POINTS/TAKE HOME MESSAGES
? Patent left superior vena cava (persistent left superior vena cava – PLSVC) has been diagnosed in 0.3-0.5% of the general population.
? It results from the persistence of the left cardinal vein that usually involutes in later life.
? Serious complications such as shock, angina, cardiac tamponade and cardiac arrest have been described during catheterization in adults with a PLSVC.
? When difficulty arise on central venous catheterization via the subclavian or internal jugular vein, variations of the superior vena cava should be entertained.
? It is paramount to ascertain the drainage pattern of a PLSVC with venogram, echocardiography, and computed tomography prior to long-term catheterization.