the most common phenomena that leads to that kind of heart activity without any actual pumping result is a ventricular fibrillation, which looks like this: http://www.ecglibrary.com/ecgs/VFNORWCH.gif, compared to a regular rhythm looking like http://www.grundkurs-ekg.de/definition/ekg1_neu.jpg. This is ( likely ) the underlying problem. What's described here is the fact that the medical personel was able to determine whether their actions ( CPR ) where effective enough to maintain blood circulation. there are, of course other metrics, like o2-saturation levels etc, but this one seems to be especially suitable.
One note aside, it's not uncommon for a resuscitation to go on for 1 or even 2 hours, it depends on the circumstances, the patient, the medical situation and most importantly, the timespan that elapsed before cpr was first administered, which was obviously quite fast in this example.
One note aside, it's not uncommon for a resuscitation to go on for 1 or even 2 hours, it depends on the circumstances, the patient, the medical situation and most importantly, the timespan that elapsed before cpr was first administered, which was obviously quite fast in this example.