Persistent left vena cava superior

Clinical History

A 54-year-old man in chemotherapy because of acute promyelocytic leukaemia was suspected of having a neutropenic infection. Because of difficult peripherel venous access, a central venous catheter (CVC) was placed for fluid and antibiotics. CVC seemed to be misplaced at control X-ray.

Imaging Findings

Shortly after the left-sided CVC was placed, the patient had what was thought to be a vasovagal reaction and might have been hypovolaemic because of sepsis. The blood pressure dropped to 80mmHg systolic and heart rate from 80 to 40beats/min. The patient quickly received 2L saline, was placed in Trendelenburg and given antibiotics. After stabilization a supine X-ray was taken (Fig. 1). The CVC was seen running vertically in the left side of the mediastinum, laterally at the level of the aortic arch before it distally turned to the right. On the X-ray the mediastinum could be distended. The anaesthesiologists called the radiologist to discuss the X-ray. Fortunately an old thorax and abdominal CT (Fig. 2, 3) existed and the radiologist could see that the patient had a left-sided vena cava superior terminating in the right atrium, not described earlier.

Discussion

A persistent left superior vena cava (PLSVC) is the most common thoracic venous anomaly described in 0.3-0.5 % of the normal background population and up to 12% of people with congenital heart abnormalities [1, 2]. Most often the right vena cava still persists and the left superior vena cava terminates in the right atrium via the coronary sinus – which was the case in this patient. A PLSVC is most often found by coincidence but is important to have in mind for cardiologist, interventional radiologist and anaesthesiologist. Especially when access is obtained from the subclavian vein on the patient’s left side. When it comes to CVCs, numerous cases of misplacement have been reported [1].

This case stresses the importance of performing a control X-ray after interventional procedures and reacting when the X-ray diverges from what's expected. Probably the best way to proceed is consulting the radiologist for scrutinizing older examinations – especially CT examinations should they exist.

If only an X-ray exist, the radiologist should suspect a catheter in a PLSVC if the catheter is placed from the left, running in a straight line in the left side of the mediastinum and distally turning to the right. To differentiate from a misplaced CVC in the left internal mammary vein or the pericardiophrenic vein a lateral view would be of great value. A CVC in a PLSVC would be located posterior to the heart whereas the left internal mammary vein runs anterior to the heart and the pericardiophrenic vein in the anterior part of the middle mediastinum [3].

Almost any imaginable misplacement of a catheter has been reported and you might only see a thoracic bleeding when the catheter is removed [1]. To differentiate a real misplaced CVC from a CVC in a PLSVC, the path of the catheter would be more twisted than described above. It's also very important to look for haemo- or pneumothorax. Most catheters can be sufficiently localised by a frontal view [3]

In this case the patient was treated immediately which postponed the control X-ray. Clinically the patient was stabilized. Generally, it must be considered a safer procedure to take a control X-ray before using the CVC. In this case the distended radiopaque mediastinum in the control X-ray was because of supine position and not because of 2 L of saline in the mediastinum. The CVC was correctly placed and could be used for further treatment.

Differential Diagnosis List

Final Diagnosis

Persistent left superior vena cava

URL:	https://www.eurorad.org/case/12893
DOI:	10.1594/EURORAD/CASE.12893
ISSN:	1563-4086