Third degree AV block (complete heart block) is often an ominous rhythm requiring close monitoring for hemodynamic compromise, progression to ventricular standstill or asystole and other lethal dysrhythmias. Significant characteristics of this rhythm are: 1) lonely P waves - P wave without an accompanied QRS complex; and 2) chaotic PR intervals. A narrow QRS denotes a higher junctional block while a wide QRS points more towards a sub-nodal block high in the bundle branches.
Heart Rate: 60 to 100 beats per minute
Rhythm: Regular
P wave: Normal in size and shape
PR Interval: None
QRS: Narrow and uniform in shape
Third-degree atrioventricular block (AVB) is characterized by a complete interruption of electrical conduction between the atria and ventricles. This results in independent atrial and ventricular rhythms, leading to a lack of coordination between atrial and ventricular contractions.
The primary treatment for third-degree AVB is the implantation of a permanent pacemaker. The pacemaker ensures proper electrical stimulation and coordinates atrial and ventricular contractions.