An atrioventricular block  (or AV block) is a type of heart block involving impairment of the conduction between the atria and the ventricles of the heart. It usually involves the atrioventricular node, but it can involve other structures.  AV block is categorized according to the degree and the site of conduction block.  In<unk> -degree AV block, all atrial impulses are conducted to the ventricles; however, there is a delay in conduction within the AV node resulting in a prolonged PR interval on ECG (>200 msec or >5 small blocks).  In other words, a<unk> -degree AV block is a slowed conduction without loss of atrioventricular synchrony.
First degree AV block classification
Third degree AV block classification
Paroxysmal supraventricular tachycardia classification
Second degree AV block laboratory findings
Pacemaker syndrome electrocardiogram
Atrial flutter classification
Atrial flutter electrocardiogram
AVNRT electrocardiogram