Manual non invasive carotid massage is indicated for two conditions. 1. Treatment of paroxysmal tachycardia  or 2. Carotid body hypersensitivity syndrome.

the link above provides enough information, however be AWARE of the conditions you must NOT perform carotid massage. first if your patient has a history of carotid artery plaques indicated by previous ultrasound or previous thromboembolic strokes. secondly always perform this maneuver in a tertiary setting so that if severe side effects such as cardiac arrest happen you will be able to manage them. I recommend using Vagus nerve stimulators prior to using carotid massage; such as drinking ice cold water and invoking gag reflex.