The most common causes of<unk><unk>  heart block are AV nodal disease, enhanced vagal tone (for example in athletes), myocarditis, acute myocardial infarction (especially acute inferior MI), electrolyte disturbances and medication. The medications that most commonly cause<unk><unk>  heart block are those that increase the refractory time of the AV node, thereby slowing AV conduction. These include calcium channel blockers, beta-blockers, cardiac glycosides, and anything that increases cholinergic activity such as cholinesterase inhibitors.
First-degree atrioventricular block
Second-degree atrioventricular block
Third-degree atrioventricular block
Ventricular escape beat
AV nodal reentrant tachycardia
Wandering atrial pacemaker
Re-entry ventricular arrhythmia
Left bundle branch block