There are three basic types of AV nodal block:
- First-degree AV block.
- Second-degree AV block. Type I second-degree AV block (Mobitz I), also known as Wenckebach block. Type 2 second-degree AV block (Mobitz II) – due to a block in or below the bundle of His.
- Third-degree AV block (complete heart block)
First-degree atrioventricular block (AV block), or PR prolongation, is a disease of the electrical conduction system of the heart in which the PR interval is lengthened beyond 0.20 seconds.
Type 2 Second-degree AV block, also known as “Mobitz II,” is almost always a disease of the distal conduction system (His-Purkinje System). Mobitz II heart block is characterized on a surface ECG by intermittently nonconducted P waves not preceded by PR prolongation and not followed by PR shortening.
Third-degree atrioventricular block (AV block), also known as complete heart block, is a medical condition in which the nerve impulse generated in the sinoatrial node (SA node) in the atrium of the heart does not propagate to the ventricle.
