Well the true origin of "be still my beating heart" is shrouded in mystery and conflict.
Some claim it is an exclamation that something is too exciting or overwhelming for one to bear; literally, that it is causing one's heart to beat too fast. Others proclaim it was originally used with the swooning earnestness of women's poetry of the Romantic period.
'Beating heart' has long been used to denote breathless excitement. John Dryden used it with that meaning as early as 1697, in The works of Virgil:
"When from the Goal they start, The Youthful Charioteers with beating Heart, Rush to the Race."
'My beating heart' was a stock expression for 18th century novelists and poets. It is first recorded in Nicholas Rowe's Tamerlane, a tragedy, 1702:
"My beating Heart Bounds with exulting motion."
The earliest citation of the full 'be still, my beating heart' comes from William Mountfort's Zelmane, 1705:
"Ha! hold my Brain; be still my beating Heart."
Sting wrote a song titled 'be still my beating heart.'
Someone else says the original quote is from Homer's Odyssey. Odysseus.
My favourite I found was from an American news editor who proudly declared - "This feminine phrase is correctly used humorously to express excitement about something surprising, like a tray of desserts or a an unexpected shoe store."
Do we still have a heartbeat of the club?
Just a heartbeat away.
In contemporary English, the expression is usually used sarcastically to imply that a situation is not nearly as exciting as has been suggested. So I'll put my Bunsen burner back in the loft.
So that's what's probably causing it Mitch. But I still can't help you with the answer.
Pretty bubbles in the air.