Types of Arrhythmia

Understanding your heart and cardiac arrhythmia

Two Scripps arrhythmia specialists examine diagnostic images in a clinical environment.

Understanding your heart and cardiac arrhythmia

Because heart arrhythmias are complex and may have underlying or contributing causes related to lifestyle choices, Scripps physicians strongly encourage and support patient education as part of the overall approach to addressing their health needs.


Our physicians believe that a self-educated patient who understands the foundations of heart disease can better benefit through active participation in his or her treatment and healing process.

Atrial fibrillation

A Scripps professional helps diagnose a particular type of arrhythmia.

Atrial fibrillation

Learn more about atrial fibrillation, a type of racing heart rhythm that’s also called AF or AFib.

Types of arrhythmia

A Scripps physician discusses different types of arrhythmia with a patient.

Types of arrhythmia

The heart’s structure

The normal heart includes four chambers:


  • Atria are the two top (left and right) chambers.
  • Ventricles are the two lower (left and right) chambers.


Blood circulating from the body to the heart enters the top right chamber (right atrium) and is pumped through a valve into the lower right chamber (right ventricle). This blood is then pumped to the lungs where it is filled with oxygen, and carbon dioxide is released.


Freshly oxygenated blood returns from the lungs to the left top chamber (left atrium) through four pulmonary veins, one from each major segment of the lungs.


The blood in the left atrium is then pumped through a valve to the bottom left chamber (left ventricle). The left ventricle is the largest and strongest of the heart’s chambers because it must pump blood to all major organs.


Watch a video about the heart’s anatomy and electrical impulses

The heart’s electrical system

A heart’s efficient pumping sequence is controlled by its electrical system that originates within a group of cells called the sinus node.


  • Sinus node (also known as sinoatrial node) is the group of cells in the upper right atrium that start a heartbeat. It’s our body’s natural pacemaker.


Depending on how active a person is (for example, sitting stationary or running at a full sprint), the sinus node sends from 50 to 160 impulses every 60 seconds that make the heart beat. These impulses cause the heart’s atria (top chambers) to contract and push blood into the heart’s ventricles (bottom chambers).


  • Atrioventricular node is a small channel of heart tissue separating the heart’s atria (top chambers) and ventricles (bottom chambers). It helps regulate the heart rate.


The sinus node’s electrical impulses travel slowly through the atrioventicular node, allowing the ventricles to fill with blood. The impulses then spread across the ventricles, causing them to contract and pump blood from the right ventricle to the lungs, and from the left ventricle to the body.

Arrhythmia definition

A heart arrhythmia is an electrical system malfunction of the heart related to its rhythm. It is characterized by an abnormal heart rhythm, notably in the pace and number of heartbeats.


Watch a video about the difference between a normal heartbeat and irregular heartbeats

Types of heart arrhythmia

There are two primary categories of irregular heartbeat:


  • Bradycardia is a very slow heart rhythm (under 50-60 beats per minute) with symptoms that can include lightheadedness, shortness of breath or possibly fainting.
  • Tachycardia is a very fast heart rhythm (over 120 beats per minute) with symptoms that can include the sensation of a racing heart, as well as lightheadedness, shortness of breath, chest tightness and fainting.


An arrhythmia is defined by which chamber or chambers of the heart are affected and how the heart is beating differently than normal. The types of arrhythmia include: