How common is inappropriate behavior after heart surgery?

Depends: I do not have enough information, but in general any person who has had a major operation such as open heart surgery, there may be early post-operative and post-anesthetic reactions with diminished mental function, outburts, poor memory, etc. The problem can be more magnified in the elderly, after an emergency surgery, or in those that may have been very weak before the surgery. Usually resolve.

Quite common: "inappropriate behavior" may relate to postoperative delirium -- a disturbance of consciousness that develops over hours to days, causes disorientation, may include hallucinations, & inability to focus, sustain, or shift attention. Incidence of delirium after heart surgery is around 40%, and may be as high as 70% at some point in a ccu admission. Treating the underlying medical problems is key.