Premature beats, or extra beats, are the most common. They are harmless most of the time and rarely cause symptoms other than a slight fluttering in the chest or a skipped beat sensation. There are two types:
- Premature atrial contractions (PACs): Premature beats that occur in the upper chambers (atria)
- Premature ventricular contractions (PVCs): Premature beats that occur in the lower chambers (ventricles)
Supraventricular tachycardia, or SVT, refers to rapid heartbeats that occur in the upper chambers of the heart. There are several types:
- Atrial fibrillation
- Atrial flutter
- AV nodal reentrant tachycardia (AVNRT) begins in the AV node, a group of cells located between the atria and ventricles. It’s a very common SVT.
- Wolff-Parkinson-White syndrome, a less common type of tachycardia
Ventricular arrhythmias start in the heart’s lower chambers (ventricles). Causes include:
The following ventricular arrhythmias are very dangerous and can cause sudden cardiac arrest (SCA) or sudden cardiac death (SCD):
- Heart failure
- Long QT syndrome and other congenital electrical disorders of the heart
- Ventricular fibrillation (VF or V-Fib): Chambers quiver instead of pumping normally
- Ventricular tachycardia (VT or V-tach): Rapid heartbeat. In older adults and people with heart conditions, VT can be a dangerous condition that can result in a weak pulse and lead to ventricular fibrillation and sudden cardiac death. If it occurs in otherwise healthy people, the condition can be tolerated.
Bradyarrhythmias occur when your heart rate is too slow. Without sufficient blood flow to the brain, you can become confused, dizzy, disoriented and even pass out.