It's called 'cardioverting', which is a lower-voltage type of defibrillation intended to 'reset' the heart into a normal sinus rhythm. My late dad suffered from cardiopulmonary disease for 20 years, and would go into V-fib regularly. It got to the point that they finally transported him to Johns Hopkins and gave him an implant. My sister was holding his hand once when the implant went off, and she said the sensation that went up her arm felt like putting your tongue on a 9 volt battery. It had to be hell for him, especially being fully awake and knowing that the shock was coming.
I would imagine a wide awake experience would be very disconcerting, my sympathies to you on the loss of your Dad, mine went home to the Lord in January ‘07.