RT Book, Section A1 Teply, Robyn A1 Packard, Kathleen A2 Sutton, S. Scott SR Print(0) ID 1179733207 T1 Arrhythmia T2 McGraw Hill’s NAPLEX® Review Guide, 4e YR 2020 FD 2020 PB McGraw-Hill Education PP New York, NY SN 9781264258062 LK accesspharmacy.mhmedical.com/content.aspx?aid=1179733207 RD 2024/03/29 AB Cardiac arrhythmia is an abnormality of impulse generation, impulse propagation, or a combination of both. Normal conduction and cardiac rhythm are initiated by the sinoatrial (SA) node. The electrical current then travels through the conduction network and enters the ventricle via the atrioventricular (AV) node and bundle of His. From the bundle of His, the electrical activity moves into the branch-like system called the Purkinje system. As the current flows through the myocardium, the excitation coordinates the contraction of the atria and ventricles. After stimulation, each group of cells experiences a refractory period in which it cannot be excited. As the electrical current meets refractory tissue, the stimulation ceases allowing for the process to begin again.