Blue Tail

One of my favorite moments in an arteriovenous malformation (AVM) resection is when the venous tail turns blue, signaling that the battle has been won. According to the venous “odometer,” the journey is nearly over and the finish line lies ahead. The AVM’s six sides are circumscribed, the arterial supply is disconnected, and the draining tail lives only through quiet venous connections. Nothing confirms the end of an AVM resection like lifting the nidus out of its resection bed still attached to its venous tail, just in case there is any unfinished dissection or unrecognized arterial supply. This roll-out maneuver works best with superficial AVMs because they deliver without sacrificing venous drainage, whereas deep AVMs deliver only after interrupting venous drainage.

Fatigue and impatience at the end of a long dissection make it easy to ignore critical warning signs, like persistent redness in the vein, which usually indicates a hidden feeding artery underneath the draining vein, a portion of the deep dissection plane that was missed, or a deep perforator on the opposite side. An AVM whose draining vein is dark or nearly dark can be aggressively manipulated to visualize these last holes and blind spots in the bed, just like an aneurysm whose afferent artery is occluded with a temporary clip and needs one final dissection maneuver before applying the permanent clip. Any AVM bleeding at this point can be safely handled by pursuing the last trickle of input.

Back Bleeding

Dividing the draining vein after an AVM has been rolled out of its resection bed is almost trivial, but dilated veins require more cautery to occlude them and can rupture during the process. Large draining veins communicate freely with venous sinuses, and back-bleeding can be brisk. Aneurysm clips close this communication with the sinus and facilitate coagulation, and can sometimes be removed after it is divided. Back-bleeding from deep draining veins can fill the surgical field or spill into the ventricles. Liberal use of clips is therefore advisable with large veins.