Taken from the PoTS UK website:
Postural Tachycardia Syndrome (PoTS) can be a life altering and debilitating chronic health condition. Simply standing up can be a challenge for people with PoTS as their body is unable to adjust to gravity. PoTS is characterised by orthostatic intolerance (the development of symptoms when upright that are relieved by lying down). Symptoms include headaches, fatigue, palpitations, sweating, nausea, fainting and dizziness and are associated with an increase in heart rate from the lying to upright position of greater than 30 beats per minute, or a heart rate of greater than 120 beats per minute within 10 minutes of standing.
PoTS tends to develop as a consequence of a number of other medical conditions and is a secondary condition. It can affect the whole autonomic nervous system. There are three parts to your autonomic nervous system:
1 The sympathetic system is responsible for your body’s ‘fight or flight’ reaction.
2 The parasympathetic system looks after the workings of your body during rest and recuperation. It also controls your heart rate and body temperature under normal conditions.
3 The enteric system controls the workings of your gut.
For me, I have to take medication to regulate my heart rate and keep it between being too high and too low. The collagen in my blood vessels doesn’t work properly due to my EDS, so I take medication that forces blood back up my body from my legs to my critical organs. It also helps to sustain a healthy and safe blood pressure which due to PoTS is often low.