Heart Blocks

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Heart block is a type of arrhythmia that affects the rate (number of beats per minute) or rhythm (the pattern of pulses produced) of the heartbeat. It consists of a blockage of electricity between the upper and the lower chambers of the heart. Normal beats are generated by the spread of electrical impulses through the heart using specialized natural wires, first in the upper chambers and then in the lower chambers. During heart block, electricity does not travel all the way through the chambers, usually due to disease in the heart’s natural wiring. Some people are born with this condition, known as congenital heart block, while most develop or acquire it during their lifetime.

Symptoms of Heart Block
There are three types of heart block, each with their own symptoms and degree of severity. General symptoms that suggest heart block include fainting, dizziness, shortness of breath, fatigue and chest pain. 

  • First-degree heart block may not cause any severe symptoms. 
  • Second-degree heart block may result in the heart skipping one or more beats, causing dizziness or fainting. 
  • Third-degree heart block may lead to dizziness, fainting or fatigue, but could also result in cardiac arrest or death.


Physicians at Houston Methodist use a test called an electrocardiogram (EKG) to detect and record the heart's electrical activity to help diagnose heart block.

Treating Heart Block
Treatment for heart block depends on the severity (degree) of the condition and the presence of symptoms.

First-degree heart block may not cause any symptoms nor require treatment. However, some research has shown that people who have first-degree heart block might be at higher risk for atrial fibrillation, an irregular heartbeat that may lead to a stroke.

If you have second-degree heart block and do not present with symptoms, a Houston Methodist doctor might simply observe you or modify your medication (some may cause heart block). If you have symptoms, however, you may need a pacemaker, which is a small device implanted under the skin in your chest that uses electrical pulses to keep your heart beating normally.

If third-degree heart block is detected, it is likely that a pacemaker will be needed.