Certified Emergency Nurse (CEN) Practice Test

The first-line treatment for unstable narrow complex tachycardia is cardioversion. When a patient presents with unstable tachycardia, defined by the presence of symptoms such as hypotension, altered mental status, signs of shock, or ischemic chest pain, immediate intervention is necessary to restore a normal rhythm.

Cardioversion is an effective procedure in this scenario as it delivers a controlled electrical shock to the heart, interrupting the abnormal electrical impulses that cause the rapid heart rate. It is particularly effective for tachycardias that involve reentrant circuits, such as atrial flutter or paroxysmal supraventricular tachycardia.

Medications, while important and used in other contexts, are not the primary immediate intervention in cases of unstable tachycardia. In these situations, the urgency of stabilizing the patient overrides the time it might take for medications to take effect. Similarly, ventricular pacing is reserved for specific cases and is not central to the initial management of unstable narrow complex tachycardia. Amiodarone, although useful for certain arrhythmias, is also not the preferred first-line treatment, especially when the patient's hemodynamic stability is compromised. Thus, immediate cardioversion is the most