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I would suggest that you speak with the cardiologist regarding an event monitor or a Holter monitor
. It would be necessary to exclude a cardiac arrhythmia
causing her symptoms. It is possible that at the time of emergency room presentation or evaluation in a physician's office, the arrhythmia is not present and therefore not documented by electrocardiogram. An event monitor would be a device which she wears that would record underlying cardiac rhythm during an event. If a documented arrhythmia can be identified, her cardiologist made then be able to treat it accordingly.
Take care and be well