What are ventricular arrhythmias?

Ventricular arrhythmias are heart-rhythm disturbances that begin in the heart's ventricles, or lower chambers. Examples include:

• Ventricular tachycardia, which involves an extremely fast heart rate, typically within the context of other serious heart disease;
• Ventricular fibrillation, which happens suddenly and without warning, and stops all heart function;
• Long QT syndrome, an electrical-system disorder that can be caused by genetics, medications, or a combination of both.