From the Guidelines
Heart blocks are classified into several types, including first-degree, second-degree (Mobitz type I and II), and third-degree or complete heart block, each with distinct characteristics and treatment approaches. The classification of heart blocks is based on the severity and location of the disruption in the electrical conduction system of the heart.
Types of Heart Blocks
- First-degree heart block: characterized by a prolonged PR interval (>200 ms) on an ECG, but with a 1:1 relationship between P waves and QRS complexes, typically requiring no treatment 1.
- Second-degree heart block: divided into two types, Mobitz type I (Wenckebach) and Mobitz type II, with the former showing a progressive prolongation of the PR interval before a dropped beat and the latter featuring consistent PR intervals with occasional dropped beats 1.
- Third-degree or complete heart block: occurs when no electrical impulses from the atria reach the ventricles, resulting in the ventricles beating independently at a slower rate, often requiring pacemaker implantation 1.
Other Types of Heart Blocks
- Bundle branch blocks (right or left): affect conduction to specific ventricles.
- Bifascicular block: involves blockages in two of the three fascicles of the conduction system.
Treatment Approaches
Treatment depends on the type and severity of the heart block, ranging from observation for asymptomatic first-degree block to emergency pacemaker implantation for symptomatic complete heart block 1.
Key Considerations
The prognosis and treatment of heart blocks depend on the underlying cause, location, and severity of the block, as well as the presence of symptoms and underlying heart disease 1.