Persistent left superior vena cava: an intensivist's experience and review of the literature. (Case Report).

Abstract: Persistent left superior vena cava is a relatively rare vascular anomaly. It is, however, the most common variation in the thoracic venous system. The anomaly is typically detected on chest x-ray after the placement of a pulmonary artery catheter or pacemaker leads. This report describes a case of persistent left superior vena cava detected after successful placement of a pulmonary artery catheter.

Key Words: congenital anomaly, persistent left superior vena cava, pulmonary artery catheter

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Persistence of the left superior vena cava (LSVC) is a relatively infrequent congenital variation. Since it is the most common congenital variation in the thoracic venous system, however, the practicing intensivist should be aware of its occurrence. It is normally asymptomatic, and is often detected during or after placement of a pulmonary artery (PA) catheter or pacemaker leads through the left internal jugular or subclavian venous routes. The prevalence is estimated to be approximately 0.3% in individuals with a normal heart and 4.5% in individuals with congenital heart disease.(1) We describe a case of LSVC in our intensive care unit (ICU).

Discussion

The embryologic development of systemic and pulmonary veins is complex and subject to considerable variation. During normal development, the anterior cardinal veins, which drain the head, neck, and arm, unite with the posterior cardinal vein in the very early embryonic stage and enter the heart as the right and left horns of the sinus venosus. With the exception that the cardinal veins on the right and the left side drain into the right atrium, the cardinal venous system is bilaterally symmetrical at this stage. Most of the left-sided cardinal system disappears, leaving only the coronary sinus and a remnant known as the ligament of Marshall. Simple failure of obliteration of the left anterior cardinal vein results in the persistence of the LSVC. This usually drains into the right atrium via the coronary sinus. On rare occasions, when developmental arrest occurs at an earlier stage, the coronary sinus is absent and the persistent LSVC drains directly into the atrium.(2)

Individuals with LSVC usually possess a normal right superior vena cava, and thus the condition is not routinely detected. The physiology is normal, and there is no hemodynamic compromise. In rare instances, the LSVC drains directly into the left atrium and may cause a small right-to-left shunt. This lesion usually has little hemodynamic effect, although a variable degree of systemic cyanosis may be seen.(2)

The importance of a persistent LSVC lies in a greater prevalence of other associated congenital cardiovascular defects and significant incidence of rhythm disturbances.(3) Wood(4) found persistent LSVC in 20% of cases of tetralogy of Fallot and 8% of patients with Eisenmenger's syndrome. Hancock(5) reported a high prevalence of leftward P axis with a normal PR interval, but its significance is not clear.(6)

A previous case report suggested that a long catheterinsertion length to obtain a wedge tracing, lack of usual central venous pressure waves, and unexpectedly high cardiac output determinations should all suggest placement via LSVC. (7) Suspicion of LSVC may arise on the posteroanterior chest x-ray, where it may appear as widening of the aortic shadow, paramediastinal bulging, paramedian stripe, or a lowdensity line along the upper left margin of the heart. (8) The typical route of a PA catheter through the aberrant vessel is shown in Figure 1. On the posteroanterior view, the catheter is seen to pass inferiorly along the left border of the mediastinum within the LSVC. It crosses the midline obliquely via the coronary sinus and enters the right atrium. Computerized tomography of the chest shows a vascular structure along the left side of the arch of the aorta draining into the right atrium.

Persistent LSVC can be accurately diagnosed noninvasively by echocardiography in conjunction with Doppler and/or contrast ultrasonography. One of the clues to the diagnosis is an unusually large coronary sinus on two-dimensional views. It appears as a dilated, echo-free space posteriorly in the atrioventricular groove between the left atrium and ventricle. Saline microbubble contrast can be used to enhance the accuracy.

Conclusion

Persistence of LSVC should be considered, especially when central venous catheterization via the left subclavian or internal jugular vein proves to be difficult, and the fluoroscopy or chest x-ray suggests an aberrant left-sided course for the catheter.

Accepted January 15, 2002.

References

(1.) Buirski G, Jordan SC, Joffe HS, Wilde P. Superior vena caval abnormalities: Their occurrence rate, associated cardiac abnormalities and angiogmphic classification in a paediatric population with congenital heart disease. Clin Radial 1986;37:131-138.

(2.) Lucas RV Jr, Krabill KA. Abnormal systemic venous connections, in Emmanouilides GC, Riemenschneider TA, Allen HD, et al (eds): Moss and Adams Hcart Disease in Infants, Children, and Adolescents: Including the Fetus and Young Adult. Baltimore, Williams & Wilkins, 1995, ed 5, pp 874-878.

(3.) Huang SK. Persistent left superior vena cava in a man with ventricular fibrillation. Chest 1986;89: 155-157.

(4.) Wood PH. Diseases of the Heart and Circulation. Philadelphia, J.B. Lippincott, 1956, ed 2, p 457.

(5.) Hancock EW. Coronary sinus rhythm in sinus venosus defect and persistent superior vena cava. Am J Cardiol 1964;14:605-615.

(6.) Momma K, Linde LM. Abnormal rhythm associated with persistent superior vena cava. Pediatr Res 1969;3:210-216.

(7.) Harrow JC, Lingaraju N. Unexpected persistent left superior vena cava: Diagnostic clues during monitoring. J Cardiothorac Anesth 1989;3:611-615.

(8.) Cha EM, Khoury GH. Persistent superior vena cava: Radiologic and clinical significance. Radiology 1972;103:375-381.

RELATED ARTICLE: Case Report

A 56-year-old woman presented with pneumonia, septic shock, and acute renal failure. A dialysis catheter was placed via the right subolavian vein. The left internal jugular vein was used for the placement of a balloon-tipped PA catheter; placement was uneventful. A chest x-ray obtained subsequently revealed the passage of the PA catheter through the LSVC into the right atrium (Fig. 1). The thoracic computed tomography (CT) scan with-contrast (obtained after removal of the PA catheter) showed the dialysis catheter in the normal right superior vena cava (intravascular opacity; Fig. 2) and the persistent LSVC (arrow; Fig. 2, A-C) as it drains into the right atrium (arrow; Fig. 2D) after joining the coronary sinus. The PA catheter was maintained in position for 3 days without complications.

From the Section of Critical Care Medicine, Rush-Presbyterian-St Luke's Medical Center, Chicago, IL.

Reprint requests to Rajit Pahwa, MD, 441 Victorian Court, west Branch, MI 48661.

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