Rare Case of Persistent Left Superior Vena Cava to Left Upper
Pulmonary Vein: Pathway for Paradoxical Embolization and
Develop

The performance of transesophageal echocardiography (TEE) has become common in the routine assessment of patients who have had transient ischemic attacks (TIAs) or stroke. As part of the TEE evaluation, agitated saline is usually injected through a peripheral intravenous (IV) line after which a Valsalva maneuver is performed to determine the presence or absence of right-to-left shunting across a patent foramen ovale (PFO). In our patient, a large volume of microbubbles was first seen in the left atrium. On careful review of the TEE, microbubbles were observed entering the left atrium through the left upper pulmonary vein.

The presence of a persistent left superior vena cava (LSVC) draining into the pulmonary venous circulation is a well described vascular anomaly.^1-4 When present, it has been described as draining primarily into the left atrium and can cause cyanosis and paradoxical embolism.^3,5 Persistent LSVC draining into the left upper pulmonary vein is an uncommon vascular anomaly that has also previously been described.^6,7 While not routinely evaluated in patients who present with TIA or stroke symptomatology, these uncommon vascular anomalies can be diagnosed by TEE when complete evaluation of the pulmonary venous anatomy is performed. Complete evaluation of the pulmonary venous anatomy is important in determining the presence of other pathways for right-to-left shunting as possible etiologies for paradoxical embolism. We describe the case of a patient who developed stroke-like symptomatology after injection of flush solution into a left arm peripheral IV line. Further evaluation, including cardiac catheterization, confirmed the presence of a persistent left superior vena cava draining into the left upper pulmonary vein. We describe what we believe to be the first reported use of the Amplatzer Vascular Plug for occlusion of a persistent LSVC-to-left upper pulmonary vein communication that presumably served as a pathway for air embolism in a patient who presented with a history of 2 TIAs.

Case Report. A 52-year-old obese female was initially scheduled to undergo gastric bypass surgery. While undergoing preoperative blood testing, she developed stroke-like symptoms with numbness and tingling of the right side of her body after normal saline was injected to flush a left arm peripheral IV line. Her symptoms lasted approximately 20 minutes. On further questioning, she had similar symptomatology after a similar experience 1 month earlier after receiving sedation administered through a left arm peripheral IV line. Neurology consultation was requested and the impression was that she had a TIA, possibly secondary to paradoxical embolism. Adult cardiology consultation was then requested to rule out the presence of a patent foramen ovale (PFO) as a possible source of right-to-left shunting. The TEE study demonstrated the presence of microbubbles in the left atrium, however, there was no PFO visualized (Figure 1). Careful review of the TEE study demonstrated microbubbles entering the left atrium through the left upper pulmonary vein (Figure 2). Because of the unusual findings on TEE, pediatric cardiology evaluation was requested.

As part of her initial evaluation, venography was performed through a left arm peripheral IV line. This demonstrated flow of contrast from the left subclavian vein into the left innominate vein and persistent left superior vena cava (Figure 3). Contrast was then seen entering the left atrium through the persistent left superior vena cava (LSVC). The recommendation was then made to proceed with cardiac catheterization to better delineate the patient’s systemic and pulmonary venous anatomy. Prior to the start of catheterization, heparin was administered, followed by complete right and left heart catheterization. Because of the patient’s age and risk for coronary artery disease, coronary artery angiography was performed, the results of which were negative for coronary artery disease. In order to fully assess her pulmonary artery and pulmonary venous anatomy, both right and left pulmonary artery angiography, including pulmonary artery wedge angiography, were performed to rule out anomalous pulmonaryvenous return and to rule out other sources of right-to-left shunting (i.e., pulmonary arteriovenous malformations). The patient’s pulmonary-to-systemic flow ratio was equal to 1.0. There was a step-up in the oxygen saturation in the innominate vein of 86%, however the saturation measurement in the distal left pulmonary artery was 71%, which was similar to the saturation measurement obtained in the superior vena cava proximal to the insertion site of the innominate vein. Selective angiography of the persistent LSVC was then performed to delineate vessel course and venous drainage (Figure 4).

The marks of an NIH Cardiomarker catheter (Medtronic Inc., Minneapolis, Minnesota) were then used to measure the vessel. The persistent LSVC measured 7.5 mm proximally, 10.5 mm at its mid-point and 7 mm near the entrance to the left upper pulmonary vein. The persistent LSVC was then temporarily occluded with a 7 Fr Wedge catheter (Arrow International, Reading, Pennsylvania) to make sure that the patient would tolerate closure of the vessel. There was no significant change in right atrial, left atrial and left ventricular end-diastolic pressure measurements. Because there was no change in the patient’s hemodynamic measurements, the decision was made to proceed with transcatheter occlusion of the persistent LSVC. Also, due to the large diameter and tubular shape of the vessel, the decision was made to occlude the vessel with an Amplatzer Vascular Plug (AGA Medical Corporation, Golden Valley, Minnesota). A 7 Fr Goodale Lubin catheter (Medtronic) was then used to position a 0.035 inch Magic Torque wire (Boston Scientific Corp., Natick, Massachusetts) into the distal left superior vena cava. A 7 Fr Guiding catheter (Medtronic) was then advanced over the Magic Wire into the distal left SVC. Using previously described techniques a 12 mm Amplatzer Vascular Plug (AVP) was advanced through the guiding catheter to successfully occlude the LSVC. After waiting a few minutes, an angiogram was performed through the guiding catheter, demonstrating occlusion of the LSVC. The device was then released in proper position. Angiography within the left SVC confirmed complete occlusion of the LSVC (Figure 5). The patient received 1 dose of IV cefazolin in the cardiac catheterization laboratory and 3 more doses over the next 18 hours. She was discharged home the following day and was instructed to take 1 aspirin daily for the next 6 months.

Discussion

Persistent LSVC is an anomaly of the systemic venous system that has been described to occur in 0.3–0.5% of the general population.^1,3 In patients with congenital heart disease, the incidence increases to 4.3%.⁸ When present, it usually drains via the coronary sinus into the right atrium. It has also been described as draining into both the left atrium and pulmonary veins.^1–4,6,7 When large, they can cause systemic desaturation. They can also serve as a pathway for paradoxical embolism that can occur secondary to right-to-left shunting.^3,5 Review of our patient’s history reveals a temporal relationship between the injection of flush solution and the immediate development of stroke-like symptoms. This is certainly suggestive of possible air embolism after injection of flush solution through the peripheral intravenous line. The fact that this occurred twice certainly points to the fact that an air embolus could have coursed through the persistent left superior vena cava into the patient’s left upper pulmonary vein and left atrium, subsequently causing the TIA. In the case of our patient, TEE demonstrated the presence of microbubbles in the left atrium. Careful and complete evaluation of all four pulmonary veins demonstrated microbubbles coursing through the left upper pulmonary vein into the left atrium. While it was certainly serendipitous that the bubble study was performed through a left arm peripheral IV line, it certainly would have been possible to miss the diagnosis of persistent LSVC-to-left upper pulmonary vein if the bubble study had been performed through a right arm peripheral IV line. Based on the information obtained from this case, the authors recommend that saline bubble injection be performed through both a right arm and left arm peripheral IV line so as not to miss anomalous systemic-to-pulmonary venous communications, which can serve as pathways for both air and thromboembolism. Once the diagnosis of possible anomalous systemic-to-pulmonary venous anomaly is suspected, these patients will need to undergo cardiac catheterization to better delineate their systemic and pulmonary venous anatomy. The authors recommend that both pulmonary artery angiography and selective pulmonary artery wedge angiography be performed to rule out anomalous pulmonary venous return and to rule out other sources of rightto- left shunting like pulmonary arteriovenous malformation. Because of the large diameter and length of the persistent LSVC, we felt that the Amplatzer Vascular Plug (AVP) was theideal device to occlude this vessel. In comparison to other occlusion devices, the AVP has several advantages, namely, delivery through a relatively small-sized sheath, multiple sizes ranging from 4–16 mm (in 2-mm increments), easy conformability to the shape of the vessel to be occluded, ability to reposition and retrieve the device prior to release, and the ability to perform angiography through the same delivery sheath.^9–11 Because of the theoretical risk of thrombus formation and possible embolization into the systemic circulation, the patient was started on aspirin for a minimum period of 6 months.

Conclusion. In conclusion, we report the successful use of the AVP for closure of a persistent LSVC draining into a left upper pulmonary vein. In patients who have TIA or stroke and who have microbubbles demonstrated by TEE in the left atrium indicative of right-to-left shunting, complete evaluation of the pulmonary and systemic venous circulation is warranted so as not to miss venous anomalies such as a persistent LSVC draining into the left upper pulmonary vein, which can serve as a pathway for both air and thromboembolism. This study also highlights the importance of close collaboration between both adult and pediatric cardiologists to make the proper diagnosis. Because of the AVP’s inherent characteristics, the authors believe that it is the ideal device for closure of these types of anomalous vessels.

References

1. Steinberg I, Dubilier W, Lukas D. Persistence of left superior vena cava. Chest 1953;24:479.

2. Edwards JE. Malformations of the thoracic veins. In: Gould SE (ed). Pathology of the Heart, 2nd Edition. Springfield, Illinois: Thomas, 1960, pp. 481–496.

3. Lucas RV, Krabil KA. Abnormal systemic venous connections. In: Moss and Adams (eds). Heart Disease in Infants, Children and Adolescents (Volume 1, 5th Edition). Baltimore: Williams and Wilkins, 1995, pp. 874–902.

4. Campbell M, Deuchar DC. The left-sided superior vena cava. Br Heart J 1954;16:423–439.

5. Freedom RM, Benson LM. Anomalies of systemic venous connections, persistence of the right venous valve and silent cardiovascular causes of cyanosis. In: Freedom RM, Benson LN, Smallhorn JF (eds). Neonatal Heart Disease. London: Springer- Verlag, 1992, pp. 485–495.

6. Odman P. A persistent left superior vena cava communicating with the left atrium and pulmonary vein. Acta Radiologica 1953;40:554–560.

7. Snellen HA, van Ingen HC, Hoefsmit EC. Patterns of anomalous pulmonary venous drainage. Circulation 1968;38:45–63.

8. Fraser RS, Dvorkin J, Rossall RE, Eidem R. Left superior vena cava. Am J Med 1961;31:711.

9. De Groote K, Verhaaren H, Suys B, De Wolf D. Percutaneous closure by a vascular plug of a fistula between the superior caval vein and the left atrium. Pediatr Cardiol 2005;26:675–676.

10. Hill SL, Hijazi ZM, Hellenbrand WE, Cheatham JP. Evaluation of the Amplatzer vascular plug for embolization of peripheral vascular malformations associated with congenital heart disease. Catheter Cardiovasc Interv 2006;67:113–119.

11. Hares, DL, Tometzki AJP, Martin R. Use of the Amplatzer vascular occluder to occlude large venous vessels in adults and children with congenital heart disease: A case series. Catheter Cardiovasc Interv 2007;69:33–39.