Case Study: An Unusual Catheter Course to the Right Atrium

Recently, our laboratory was performing a catheter ablation of paroxysmal atrial fibrillation in a patient with a permanent pacemaker previously implanted from the left axillary venous approach.  The fellow placed a decapolar catheter from the left femoral vein, but it took an unusual course to the right atrium.    Attempts to place the catheter via a more typical course could not be achieved.

Here are the RAO and LAO fluoroscopic images he saw (labeled for your convenience):

RAO Fluoroscopic Image (click to enlarge)

LAO Fluoroscopic Image (click to enlarge)

At first, the fellow thought the catheter was extravascular was the catheter passed behind the heart, but continued advancement resulted in the catheter entering the right atrium.

Here's the LAO Cineangiogram of the finding that helped us identify the cause:

Here's the RAO image of the same shot:

What is this?  What happened next?

-Wes

PS:  If you can't wait, here's a link to a pretty illustration of the anatomy.  Note the hepatic drainage to the right atrium is separate from the drainage of the IVC in this anomaly.  Here's another link to factoids from the radiology literature regarding this interesting finding.