Complex sentence: Ventricular fibrillation is a medical emergency that requires prompt Basic Life Support interventions because should the arrhythmia continue for more than a few seconds, it will likely degenerate further into asystole ("flatline").
Split into simpler sentences: Ventricular fibrillation is a medical emergency that requires prompt Basic Life Support interventions. If this arrhythmia continues for more than a few seconds, it will likely degenerate further into asystole ("flatline").