A single precise strike to the right location is enough to disrupt most commercial heart monitors. Fortunately, the calculations involved in finding that location are beyond normal human cognition.
Anatomy Analysis is an augment; when an agent with Anatomy Analysis makes an attack with a ranged weapon against a guard with a Heart Monitor, the effect of the Heart Monitor is ignored for a cost of 3 PWR. This allows an agent to kill human guards without raising the alarm level, and to knock them out without raising the alarm level in Expert Plus and Endless Plus modes. If a non-lethal attack is made, the target's Heart Monitor is only ignored for that attack, not permanently disabled.
The effect of Anatomy Analysis is not optional, so it always applies when the agency has at least 3 PWR (after paying the weapon's PWR cost, if any), unless the target's Heart Monitor has already been disabled. There is no effect when the agency does not have enough PWR to use it.