For me *okay, I'm human* it generally just means 
an irregular heart-beat.  Sometimes, the rhythm 
is just off.  Or, it may be a strange 
compression in my chest.  But other than that, 
things are pretty normal.  I'm hoping that the 
same is true for your kitty.

As for your other cat, be thankful that surgery 
is an option.  Vets can do amazing things these 
days.  So, until I hear you tell me other-wise, 
I'm keeping my fingers crossed!

*huggle*