Tehran University of Medical Sciences Frontiers in Emergency Medicine 2717-3593 6 4 2022 07 06 e60 e60 Jerry W. Jones Chief Instructor, Medicus of Houston, Texas, USA 2022 07 06 2022 07 06 This is the fourth installment in the electrocardiogram (ECG) interpretation series by Jerry W. Jones MD FACEP FAAEM for this journal. At first, he discussed simple atrioventricular (AV) dissociation versus AV dissociation caused by third degree AV block; then, he shares some very important pearls regarding ECG interpretation. And in latest one, he pointed to the importance of Hexaxial Reference Grid. For this paper, some valuable references were reviewed. https://fem.tums.ac.ir/index.php/fem/article/view/1040 https://fem.tums.ac.ir/index.php/fem/article/download/1040/413