A patent foramen ovale (PFO) is a small flap-like opening between the heart’s upper chambers that failed to close after birth. Most people never feel it, but when symptoms show up they’re usually brief and odd.

Sudden migraine with aura is the common clue. Flashing lights, zig-zag lines, or numb face that last 20–60 minutes, often after exercise or dehydration.

Brief dizziness or “gray-out” spells happen. You feel woozy, lose color vision for a few seconds, then snap back.

pins-and-needles or weakness on one side can mimic a mini-stroke, but clears within minutes.

Shortness of breath with exertion pops up in some. You puff faster than friends on stairs even though your lungs sound clear.

Chest flutter or skipped beats may be felt if the flap flips open wide.

Late red flag is an actual stroke under age 55—an alarm that a clot slipped through the hole.