Tehran University of Medical Sciences Frontiers in Emergency Medicine 2717-3593 6 1 2021 11 16 e13 e13 Jerry W. Jones Chief Instructor, Medicus of Houston, Texas, USA 2021 11 15 2021 11 15 One of the most difficult decisions for many physicians and advanced practice providers occurs when having to distinguish between simple atrioventricular (AV) dissociation and AV dissociation caused by a third degree AV block. Third degree AV block is only one cause of AV dissociation and it is a very infrequent cause. The majority of simple AV dissociations are caused by variations in the balance of sympathetic and parasympathetic inputs from the autonomic nervous system. All of us probably experience an occasional episode of simple AV dissociation while we are asleep. Treatment for simple AV dissociation may be as simple as having the patient get out of bed and walk around the room a few times, while AV dissociation caused by a third degree AV block is going to require an emergent placement of a permanent pacemaker. In order to make this decision properly and confidently, you must have a very clear understanding of the difference. Here, in this educational paper, we aim to discuss more in this regard. https://fem.tums.ac.ir/index.php/fem/article/view/893 https://fem.tums.ac.ir/index.php/fem/article/download/893/377