Types of AV block: when the “gatekeeper” slows down or blocks the passage
For the heart to contract in a coordinated manner, the electrical signal generated in the atriaThe atria are the two upper chambers of the heart. They act as reservoirs for blood that will fill the ventricles. must reach the ventricles.
To read: The electrical system
This passage is only possible by going through a single checkpoint: the atrioventricular node — the “electrical gatekeeper.”
It is here that the signal must “show its passport” before continuing its path. Under normal circumstances, this gatekeeper allows each impulse to pass while protecting the heart from excessively rapid rates. It ensures that the atriaThe atria are the two upper chambers of the heart. They act as reservoirs for blood that will fill the ventricles. and ventricles work together, in the right order and at the right time.
However, this “checkpoint” can be influenced. Certain factors may slightly speed up conduction, but many others tend to slow it down. When this slowing becomes more pronounced, or when some impulses no longer pass through, this is referred to as an atrioventricular block (AV block).
Different Types of Atrioventricular Block (AV Block)
AV blocks are classified according to the severity of the delay or interruption:
- First-degree AV block: the signal passes, but more slowly
- Second-degree AV block: some signals pass, others do not
- Third-degree AV block: no signals pass through; the atriaThe atria are the two upper chambers of the heart. They act as reservoirs for blood that will fill the ventricles. and ventricles beat independently
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