Atrioventricular<unk>  may be classified anatomically by the site of<unk> , usually divided into atrioventricular nodal, intra-Hisian (within the His bundle itself), and infra-Hisian (below the His bundle).<unk>  is defined as a delayed escape rhythm which repetitively<unk> s conduction from the atria to the ventricles, thereby causing syncope, conduction defects such as asystole and sudden cardiac death. It may or may not be associated with Phase 3 or Phase 4 conduction defects. It may be due to an increased vagal tone, innately low adenosine levels or an intrinsic conduction defect, all of which lead to different ECG presentations. Insufficient data is available regarding the exact etiology, diagnostic study of choice and treatment of<unk> s. It can be thought of more as a disease of exclusion. However,efforts must be made to have a standardized approach to such patients. The site of<unk>  may be clinically important and can be determined by invasive EPS when not apparent from the ECG and clinical circumstances. In general, atrioventricular<unk>  at the atrioventricular nodal level is associated with slower progression, a faster and more reliable atrioventricular junctional escape mechanism, and greater responsiveness to autonomic manipulation such as atropine, isoproterenol, and epinephrine administration. In contrast, atrioventricular<unk>  within or below the His bundle may progress rapidly and unexpectedly, is associated with a slower and more unpredictable ventricular escape mechanism, will not respond to atropine but will sometimes improve with catecholamines.
Paroxysmal AV block
Fascicular VT
Wide complex tachycardia
Atrioventricular dissociation
Wandering atrial pacemaker
Narrow complex tachycardia
Isorhythmic A-V dissociation
AV reentrant tachycardia