The heart can have rhythm problems in some people after bypass surgery, which is why they leave a wire dangling from the chest, to attach a pacemaker if necessary. In most cases this resolves itself when the heart recovers from any inflammation in the areas of grafting and usually takes three to five days. I'm sure cardiologists are watching her carefully, but haven't they spoken to you about her condition at all? whether they feel there's a more serious underlying problem or not?