Complete superior vena cava obstruction.

Magnetic resonance venography was performed to better understand venous anatomy in a woman with failed pacemaker implantation. Compared with a healthy subject (Panel A), her maximal intensity projection images (Panel B) showed an absent superior vena cava (SVC; arrowhead). The subclavian veins (RSV & LSV) were absent, although bilateral subclavian arteries (RSA & LSA) were preserved. Upper body collateral drainage occurred though paravertebral veins, the azygous vein and enlarged intercostal veins (*), appearing similar to arterial “rib-notching” that is seen with aortic coarctation (Panel B). MRI 3D reconstructions (healthy subject [Panel C] and patient [Panel D]; Supplemental Videos) show the distorted venous anatomy. In addition to engorged intercostal veins (IC), our patient has a “bare” aorta (Ao), without superimposed SVC and brachiocephalic veins (RBV & LBV). The sharp vessel “cut-off” suggests an acquired obstruction, likely secondary to prior catheters and lines. Figure 1 A cardiac resynchronization system was successfully implanted via an iliofemoral vein. With increased percutaneous interventions, cardiologists will likely confront similar anatomy in the future.