It means that enough current traversed the chest and depolarized enough myocardium to realign muscle fibers back into time. The natural pacemaker cells like the SA node tend to be stunned more by defibrillation than other myocardial structures and it is not uncommon for 1-2 minutes of asystole to exist after the defibrillation impulse. Good CPR here, can help bridge the gap until a natural pacemaker recovers and takes over. Non intubated patients can make agonal noises. Most agonal respirations are deep and slow, with a snoring quality.
Some experts believe that defibrillation itself makes the heart even more irritable.
While some may think that you should just defibrillate again, it is better to prevent the reoccurrence so that myocardial damage from defibrillation can be minimized. Talk about Kodak's experience.