In this scenario the patient has inadvertently contacted both a source of current (it does not have to be AC, as shown) as well as a common return pathway during an invasive cardiac medical procedure. If the current flowing is below the threshold of perception, or the patient is sedated, or anaesthetized, there may be no pain or reflex response of either arm. If the current flow continues for sufficient time, at sufficient strength, the patient may die. Because of the low current and lack of patient response, this death may be unexpected, and without any obvious cause. In practice, however, this has never been proven to have happened.