Paroxysmal supraventricular tachycardia: when to get help
Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Call emergency services if a rapid heartbeat occurs with:
Fainting or inability to stay awake
Severe or persistent chest pain
Severe trouble breathing
New confusion, weakness, or difficulty speaking
Signs of shock, such as cold clammy skin or marked collapse
Do not drive yourself for emergency care.
If severe symptoms occur, sit or lie down to reduce the chance of injury while help is arranged.
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Seek prompt medical advice if an episode lasts longer than usual, will not stop with the method you were taught, or is accompanied by increasing weakness or breathlessness.
3
Does any of this apply?
Book an appointment
Arrange a routine medical appointment if you have repeated episodes of a fast heartbeat, even if they stop on their own.
Assessment is also appropriate for a first unexplained episode, especially if you have heart disease, are pregnant, or have a family history of sudden cardiac death.
Every sign above is quoted from the sofidex article on Paroxysmal supraventricular tachycardia. If you are not sure, err upward — it is always reasonable to be checked.