Has your Dad's potassium level been checked lately? Is he on any diurectics for his swelling? If he is, these drugs (Such as Lasix) tend to flush potassium out of the body. Potassium is necessary in controlling the heart beat and if it's low can cause these symptoms.
Just a thought. We had the same problem for my Mom.
I would give the Doctor a call as soon as possible.
Hugs to you and yours,
My Mom lost her one year battle with CC on April 3, 2009.
"A prognosis is simply an audit of how truly precious each day is. Live each day to the maximum, celebrate what was, and what is - Don't spend your life looking forward to what will or might be." .... words of wisdom from my beloved son on hearing of his grandmother's CC prognosis.