Dysrhythmias (also called arrhythmias) are abnormal heart rhythms arising from disturbances in impulse formation, conduction, or both. They range from benign (occasional premature atrial contractions) to immediately life-threatening (ventricular fibrillation and pulseless ventricular tachycardia). Atrial fibrillation is the most common sustained dysrhythmia in US adults and a leading cause of embolic stroke, while ventricular fibrillation is the most common rhythm in sudden cardiac arrest. For the NCLEX-RN, the overarching priority is to determine whether a rhythm is hemodynamically stable or unstable, recognize the most common rhythms by their defining features, and implement the correct, time-critical intervention. Key decision framework: 1. Is the client symptomatic — hypotension, chest pain, altered level of consciousness, or acute dyspnea? If so, the rhythm is UNSTABLE and demands immediate intervention. 2. What is the rate? Tachycardia is above 100; bradycardia is below 60. 3. Is the rhythm regular or irregular? 4. Are the QRS complexes narrow (less than 0.12 second, meaning supraventricular) or wide (more than 0.12 second, meaning ventricular or aberrantly conducted)? 5. What is the relationship of P waves to the QRS? Normal...