The different types of ventricular tachycardias include:

• Premature ventricular contractions (PVCs). Occur when an early signal from the lower chambers of the heart (ventricles) prompts an early heartbeat. Following this beat, a brief pause may occur until a properly timed ventricular contraction takes place. This is often perceived as a “skipped” beat, which can lead to ventricular tachycardia, as described below.
  
  
• Ventricular tachycardia (VT). A potentially fatal type of heartbeat (more than 100 beats per minute) that arises from the ventricles. Left untreated, ventricular tachycardia could lead to cardiac arrest or ventricular fibrillation.
  
  
• Ventricular fibrillation (VF). A result of very fast and uncontrolled electrical signals that cause the heart to quiver rather than beat in any efficient or effective manner. Ventricular fibrillation often leads to sudden cardiac death if not treated immediately. Often, the first sign of VF is sudden fainting (syncope).