So I had a test in Anatomy on the heart, so I've studied and managed to realize some things with Karda Nui. Ignore if you're not interested.

Probably coincidence, but "av" (like in Av-Matoran_ is used in some heart terminology (AV Node, AV Bundle), meaning Atrio-Ventricular.

I'm guessing the Codrex is supposed to be the Sinoatrial Node, and that the Energy Storms are like a heart beat.

There is a western entrance to Karda Nui, and the only way for blood to first get into the heart is by the Venae Cavae, which are connected to the right side of the heart.