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Heart Block

In the normal heart, the natural pacemaker (electrical system), exists in the top of the heart. The signal is sent down specialized conduction tissue to the bottom chambers of the heart to signal those chambers to pump. In heart block, there is either damage or delay in signaling in this conduction tissue, which prevents adequate and timely signaling of the lower chambers of the heart.

The more severe the block the slower the heart is able to pump. At worst, the heart block can prevent communication between the top and bottom chambers (“complete heart block”).

Heart block can occur due to medications, heart attacks, valve disease, diseases that damage the electrical tissue in the heart, or trauma amongst other causes. Aging of the electrical system also can be a common cause of heart block.


  • In early stages and in milder forms, heart block often has no symptoms.
  • As heart block worsens, it can lead to exertional fatigue, slow pulse or shortness of breath.
  • In the worst cases, patients can experience dizziness and passing out spells (syncope).

Diagnostic Tests


  • The first step is to decrease the dose of any offending medications or stop them altogether.
  • If the cause is from blockages in the arteries of the heart, fixing those blockages can sometimes improve the heart block.
  • If the heart block is severe enough, the patient may require pacemaker placement.

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