Final answer:
Patients with unstable tachycardia should receive immediate cardioversion or defibrillation, which are procedures that use controlled electrical shocks to correct the heart's rhythm.
Step-by-step explanation:
In patients with unstable tachycardia, immediate cardioversion or defibrillation is recommended. Tachycardia, a condition with a resting heart rate (HR) above 100 beats per minute (bpm), can be caused by various factors, including extreme stress, fever, anemia, or heart conditions. Resting HR should be assessed after a period of rest to differentiate it from exercise-induced elevated HR. When tachycardia presents with severe symptoms like dizziness, chest pain, or fainting, urgent intervention with cardioversion or defibrillation is indicated to restore normal rhythm and prevent complications. These procedures deliver a controlled electrical shock to the heart, which can stop the abnormal rhythm and allow the heart's natural pacemaker to regain control.