Heart Block (AV Block)

What is Heart Block?

Heart block (also called AV block) means that the relationship between the atria and ventricles of the heart is affected, mildly or severely impaired. There are first, second and third degree blocks. Heart block is diagnosed by ECG or rhythm holter. A 1st degree heart block is a milder type of block and the conduction time between the atria and ventricles is prolonged. It usually does not cause many complaints. In 2nd and 3rd degree heart blocks, each atrial beat is not followed by a ventricular beat. They may cause complaints. Advanced blocks can be life-threatening if not treated urgently.

Apart from AV block, there is also a condition called SA block. Here, there is a problem with the spread from the place where the first stimulus originates in the heart to the atria. This can sometimes cause serious cardiac arrest. You can watch this video to understand how a normal heart works.

I wanted to make a video about blocks in the heart and the complaints it causes. You can watch it below.

What are the causes of heart block?

Heart block or AV block occurs when there is a conduction defect in the electrical system within the heart. Normally, each atrial beat is followed by a ventricular beat. In AV block, this is disrupted. The causes are usually

  • Degeneration of the conduction system
  • After cardiac interventions or operations
  • Effect of medicines
  • Rarely aortic valve infections

can be sorted as. Rarely, people may have this block from birth.

What are the symptoms of AV block?

The symptoms depend on the type of block a person has. There are 3 types of AV block:

First-degree AV block

1st degree heart block is the mildest type of block. There are usually no symptoms. It rarely causes complaints.

Second degree AV block

Second-degree heart block is more serious than first-degree. There are two subtypes. Type 1 and Type 2. Type 2 is more serious. People with second-degree block may have the following symptoms;

  • Fainting, dizziness, feeling like you are going to faint
  • Feeling tired
  • Difficult breathing
  • Chest pain

Sometimes it may not cause complaints.

Third degree AV block

Grade 3 heart block is the most serious type of AV block. Most people with third-degree heart block develop symptoms. It can cause the same symptoms as second degree, but tends to be more severe. Third degree heart block can be life-threatening.

How is heart block treated?

The treatment of heart block depends on the degree of the block:

  • Most people with first-degree heart block do not need treatment.
  • Some people with second-degree type 1 block may need a pacemaker.
  • Most people with type 2 and third-degree heart block (unless it is a congenital block) need a pacemaker.

A conventional pacemaker consists of a battery and wires. The battery is placed in a pocket under the left or, more rarely, the right collarbone, above the pectoral muscle. The cables are sent to the heart via a vein in the arm. The battery detects the heartbeat and, if necessary, gives an electrical impulse to the heart to prevent the pulse rate from falling below certain values.

Wireless batteries are also available. These weigh 1.5-2 grams and are placed in the right ventricle. Wireless pacemakers do not contain batteries and cables. You can watch a detailed video explanation in the pacemaker types article

Left branch block and 1 degree heart block sample ECG
Left branch block and 1 degree heart block sample ECG

Reference: Atrioventricular Block

Update: Feb 13, 2024

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Picture of Prof. Dr. Taylan Akgün
Prof. Dr. Taylan Akgün

He is a cardiologist specialised in the diagnosis and treatment of heart rhythm problems (ablation), pacemaker procedures.
He works in Istanbul province.

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