Elderly father had heart valve replacement surgery 6 wks. ago now a week ago became very agitated and confused, what is going on?

Variable: Many possibilities ranging from poor oxygenation, to metabolic diseases, to valve failure, etc. He should immediately be taken to his cardiologist or closest emergency department for evaluation.

Get checked: Stroke embolism chemical imbalance anemia several serious possibilities.

Not unusual: First, check post-op meds, especially narcotics, as anti-cholinergic effects in such meds can promote delirium in elderly pts. Also, he may have experienced some hypoxia, a stroke, or decompensation of pre-existing alzheimer's. Please discuss with the surgeon, your internist and all involved in the procedure.