Symptoms of AV Nodal Blocks

First Degree AV Block

Patients with first degree AV block usually don’t have any symptoms. However, in some cases, it can reduce the person’s tolerance for exercise.

feeling dizzy

Second Degree AV Block

Depending on the stage of the second degree AV block, symptoms may include light-headedness, dizziness, and syncope. Syncope most commonly happens when the second degree AV block is on the verge of transferring into the third degree AV block, since a large number of impulses are unable to pass through atrioventricular node.

Third degree AV block

This type of AV block is actually better tolerated by the patients than second degree AV block Mobitz 2. Despite the fact that atria and ventricles are contracting independently of one another, the heart can perform its function quite well. Most common symptoms include:

  • Minimal symptoms of hypoperfusion which include cyanosis and coldness of hands and feet.
  • Fatigue – due to a decreased pumping action of the heart, the person’s tolerance for exercises is reduced.
  • Dizziness – hypoperfusion also affect the brain making the person dizzy and, in some cases, lose consciousness.
  • Chest pain – this symptom is usually caused by the underlying disease rather than by the AV block itself.

Infra-Hisian Blocks

Blocks that occur below the bundle of His are the most dangerous since the impulse from atrioventricular node cannot reach the ventricles. The cells of the ventricles (Purkinye fibers) can generate their own impulses; however, they can do so at a maximum rate of 40 times per minute, leading to severe bradycardia. This can lead to syncope, confusion, dyspnea, and even sudden death.



Next Chapter: Diagnosis of AV nodal blocks


To learn more about Cardiology, we recommend the following websites: