How it works. After being sedated via intravenous medication, a tiny region in close proximity to a major vein is numbed on either the neck, groin, or forearm. A needle and sheath are placed into the vein and the surgeon will guide specialized catheters into the incision through the sheath to numerous areas of the heart. The electrode ends of these catheters are then used to test areas of the heart in order to identify the tissues that are responsible for inducing the irregular heart rhythm. Once they have been identified, the problematic tissues are then dismantled or destroyed using lasers, extreme heat energy called radio frequency, or extreme cold energy called cryoablation. This blockage or destruction will allow the electricity to flow through the correct paths in the heart without the previous disruptions.