Arrhythmias affect millions of people worldwide and can result in heartbeats that are either too slow, erratic, or too fast. These arrhythmias cause the blood to pump inefficiently, resulting in dizziness, fatigue, or other symptoms.

Slow heartbeats are often the result of a failing SA node, causing the blood to pump too slowly.

Erratic heartbeats can have various causes, and are often very serious.

Fast heartbeats cause the blood to pump inefficiently. There are two types of fast heartbeats: focal arrhythmias and reentrant arrhythmias.

• In focal arrhythmia (such as focal tachycardia), a site other than the SA node is initiating rhythms, which may cause the heart to beat faster.
  
  
• In reentrant arrhythmias (such as atrial flutter), the electrical signals circulate repetitively in a closed circuit.