system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Chest pain during a panic attack can be mistaken for a heart attack. What happens during heightened anxiety that causes chest pain in the absence of a cardiac event?
gpt
Psychiatrist here. Think of a panic attack as your body wrongly believing that you are in a life or death situation. Your brain goes into full fight or flight and prepares you for potentially disastrous scenarios. Your blood vessels tighten to keep your blood pressure up if you begin to bleed, your heart rate increases to make sure your muscles have what they need to run fast or fight, your gut wants to purge everything because you don’t want to waste energy digesting when you’re running or fighting, your sensitivity to pain begins to filter for worst case scenarios (i.e it is safer to assume the worst thing is happening when interpreting physical sensations so your brain will assign the worst possible causes to things your body senses in an attempt to keep you safe). 

Lots of other things happen but these are the easiest to understand as causing chest pressure. Your blood pressure is up and your heart is working hard. Additionally a lot of people have nausea and reflux which can be interpreted as chest pain, especially when you’re in a heightened state.