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 for:
Severe or sudden difficulty breathing
Fainting or difficulty staying awake
New chest pressure or pain that does not settle
Blue or grey lips, marked confusion, or severe weakness
These emergency symptoms may have causes other than constrictive pericarditis, but they need immediate assessment.
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 known symptoms worsen quickly, you become breathless at rest, swelling increases over a few days, urine output falls noticeably, or a fast or irregular heartbeat causes weakness or dizziness.
3
Does any of this apply?
Book an appointment
Arrange a routine medical appointment if you develop gradually increasing ankle swelling, abdominal enlargement, breathlessness during activity, unexplained weight gain, or persistent tiredness.
These symptoms have many possible causes and do not confirm constrictive pericarditis.
Every sign above is quoted from the sofidex article on Pericarditis - constrictive. If you are not sure, err upward — it is always reasonable to be checked.