Although far less lethal than guns, conducted electrical weapons (a.k.a. stun guns) still pose the risk of cardiac arrest occurring after someone has been incapacitated. To help minimize the risk of that happening, researchers have successfully customized a stun gun to also monitor the target’s heart rate at the same time.
Source: Gizmodo – Someone Invented a Stun Gun That Monitors Heart Rates to Avoid Cardiac Arrest