A man suddenly developed an irregular heartbeat, but it went away unexpectedly after a rectal exam. (Image credit: Halfpoint Images via Getty Images) The patient: A 29-year-old man in Queens, New York The symptoms: As the man was walking home one night, he suddenly started feeling heart palpitations — accelerated heartbeats at irregular intervals — that alarmed him, prompting an immediate visit to the emergency room. Article continues below Get the world’s most fascinating discoveries delivered straight to your inbox. Medication usually restores the heart's normal rhythm within hours — but in this case, the rectal exam achieved a similar result instantly. Notably, during the rectal exam, the patient was instructed to bear down and strain without exhaling, a technique called the " Valsalva maneuver ." It's also used to clear pressure from the middle ear and is known to increase activity in the vagus nerve.…