AV blocks Flashcards
(12 cards)
What is AV dysfunction?
A disorder of impulse conduction in the AV node
What characterizes 1st-degree AV Block (AVB)?
Prolonged PR interval (PRI) > 0.20 seconds
All atrial impulses are conducted to the ventricles with no hemodynamic adversity.
List the characteristics of 1st-degree AV Block.
- All atrial impulses conducted to ventricles
- No hemodynamic adversity
- Rate varies with underlying rhythm
- Regular R-R intervals
- 1 P wave for every QRS complex
- QRS duration: 0.06 - 0.11 seconds
What is the main characteristic of 2nd-degree AV Block?
Some atrial depolarizations fail to reach ventricles
Describe Type I 2nd-degree AV Block (Mobitz I/Wenckebach).
Progressive lengthening of the PRI until an impulse is blocked
It is a benign condition and usually transient.
What distinguishes Type II 2nd-degree AV Block?
Constant PR intervals with some blocked impulses
What does a 2:1 AV Block indicate?
A specific type of block with particular ECG characteristics
What defines 3rd-degree AV Block?
Severe depression of impulse propagation through the AV node
No impulses are conducted to the ventricles.
What are the characteristics of 3rd-degree AV Block?
- Escape rhythm initiates ventricular depolarization
- AV dissociation visible (independent P-P and R-R intervals)
- Requires pacemaker implantation to prevent hemodynamic adversity
How is 1st Degree AVB identified?
Prolonged PRI > 0.20 seconds
How do you differentiate between 2nd Degree AVB Type I and II?
Measure PRI: progressive lengthening in Type I, constant in Type II
What is a viable rhythm in 3rd Degree AVB?
Latent pacemakers (Junctional or Ventricular escape rhythm)
Spontaneous depolarization of pacemaker cells occurs, with lower inherent rates further down the heart.
