Trying to identify disease similar to "fainting goats"?

someone i know described to me a condition that she has where if she gets overly anxious, surprised, etc., her heart fails to pump enough blood to her brain. she ends up losing all of her senses and fainting, and if she is not flat on the ground, blood will not flow to her brain and she could sustain brain damage. it's the same idea as what's known as "fainting goats" disease, but it has to do with something that does not work properly specific in her heart, not her muscles or brain or anything else.