Case In Point: Persistent left superior vena cava in an elderly man with pneumonia

The case

An 84-year-old man was admitted to the ICU with acute renal failure, pneumonia, and sepsis. He did not have a significant personal or family history of cardiovascular disease.

A central venous catheter was placed through the left subclavian vein without complication. Central venous pressure was 5 mm Hg. A postprocedural frontal chest radiograph revealed the catheter lying at the left side of the aorta, which raised the suspicion of a congenital vascular anomaly (Figure 1).

Transthoracic Doppler echocardiography confirmed the diagnosis of PLSVC. The echocardiogram showed the dilated coronary sinus as an echo-free space posteriorly between the left atrium and the ventricle (Figure 2). Saline contrast injected into the left antecubital vein drained through the PLSVC into the enlarged coronary sinus and then into the right atrium.

The Doppler color flow study revealed mild to moderate tricuspid regurgitation. The estimated systolic pulmonary pressure was 32 mm Hg, and the estimated ejection fraction was 60% without evidence of wall motion abnormalities. There was no evidence of diastolic dysfunction, and findings from the remainder of the study were normal. CT of the chest was done to evaluate the anomaly and the lung parenchyma (Figure 3).

Despite the free flow of venous blood from all catheter ports, the line was removed. The patient clinically improved with fluids and antibiotics, and he was discharged.

Discussion

PLSVC is an uncommon congenital defect that is the most common anomaly of thoracic venous return. It is found in about 0.3% of the general population and in 3% to 10% of patients with congenital heart disease.¹ It is most commonly discovered after central venous or pulmonary artery catheter placement. PLSVC is associated with the presence of the right superior vena cava in 82% of cases.²

In the normal early embryonic stage, the anterior cardinal veins draining the head, neck, and arms join with the posterior cardinal vein and enter the heart as the right and left horns of the sinus venosus. Both the right and the left cardinal veins drain into the right atrium 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 PLSVC. In most cases, PLSVC drains into the right atrium via the coronary sinus. However, if developmental arrest occurs at an earlier stage, the coronary sinus is absent and the PLSVC drains directly into the right atrium.

An accurate diagnosis of PLSVC is possible when a contrast-enhanced CT scan demonstrates that PLSVC is draining into the coronary sinus. The diagnosis can also be based on findings of transthoracic Doppler echocardiography, as was the case with our patient.³ Venography with simultaneous chest radiography is another noninvasive bedside test that can be helpful for confirming the diagnosis.⁴ Other reported diagnostic modalities are angiography and MRI.^5,6

This isolated anomaly does not require specific treatment. However, it is important that internists and intensivists be able to recognize PLSVC because of its association with other cardiovascular malformations and because of the difficulties that this anomaly can cause during central venous catheterization, pacemaker electrode placement, and cardiopulmonary bypass surgery.^7,8 Such anomalies include tetralogy of Fallot, Eisenmenger syndrome, coarctation of aorta, atrial septal defect, ventricular septal defect, and endocardial cushion defect. Some of these accompanying lesions can increase the risk of paradoxical embolism.⁸

References:

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