Firstly, let’s follow the current path. There is a generic source of current. This source can be either large or small, as only a small voltage is required to drive the low current for micro-shock. Such sources might be, a wall socket, a faulty item of equipment, an inappropriate item of equipment, a poorly designed item of equipment, or an item of equipment designed to deliver current into the body. Our patient has unfortunately contacted one such source and current is dispersing through their right arm and upper torso, to eventually converge on a catheter (as labelled – but it could be a lead or wire) that is placed into their heart. This concentration of current flow at the heart muscle is the danger from micro-shock. If the catheter is conductive and insulated, the current may follow the catheter, emerging through the skin into some other item of equipment. For the circuit as shown to be complete, the conductive part of the catheter needs to also be connected to ground within this equipment. Finally, the hazardous circuit is complete – current can flow and if it continues the patient is in mortal danger. Again, while this is theoretically possible this has never been proven to have actually happened.