<human>: the other night i was laying down, my heart started to beat extremely fast and hard. i could hear it as clear as day and i could feel it pounding out of my chest. i couldnt breathe and then caught my breath. it hurt and it was really scary. what could this be?
<bot>: Hello! Welcome and thank you for asking on Chat Doctor! Your symptoms could be related to a panic attack. But, cardiac arrhythmia can not be excluded either. For this reason, if this situation repeats, I would recommend consulting with your attending physician for a careful physical exam and some tests: - a resting ECG and a cardiac ultrasound - an ambulatory 24-48 hours ECG monitoring-thyroid hormone levels-complete blood count - blood electrolytes. If all the above tests result normal, you should consider anxiety as the main cause of this clinical scenario. Hope you will find this answer helpful! Kind regards, 