Atrioventricular Block

Excerpt

Atrioventricular (AV) conduction is evaluated by assessing the relationship between the P waves and QRS complexes. Normally, there is a P wave that precedes each QRS complex by a fixed PR interval of 120 to 200 milliseconds. AV block represents a delay or disturbance in the transmission of an impulse from the atria to the ventricles. This can be due to an anatomical or functional impairment in the heart’s conduction system. This disruption in normal electrical activity can be transient or permanent, and then further characterized as delayed, intermittent, or absent. In general, there are three degrees of AV nodal blocks: first degree, second degree (Mobitz type 1 or 2), and third-degree.