Postural orthostatic tachycardia syndrome[?] (POTS) is a form of tachycardia that occurs with a change in body position (eg, going from laying down to standing up) and which is generally due to dysautonomia[?].
Tachycardia is a general term that is applied in a lot of different contexts. Most generally it means pathologically increased heart rate.
Tachycardia, as applied in adult medicine, is defined as a heart rate of over 100 beats per minute (BPM).
See also : Cardiac arrhythmia