In which situation is transcutaneous pacing indicated?

Transcutaneous pacing is indicated in situations where there is a significant and symptomatic bradycardia or a complete heart block that compromises cardiac output, such as a third-degree AV block with low blood pressure. In this scenario, the electrical impulses are not effectively reaching the ventricles, leading to inadequate heart rate and thus insufficient blood flow to vital organs. The presence of low blood pressure indicates that the patient's hemodynamics are unstable, necessitating immediate intervention to restore an adequate heart rate and improve circulation.

Transcutaneous pacing acts as a temporary measure to stimulate the heart externally until a more permanent solution, such as transvenous pacing or other treatments, can be instituted. This method can effectively increase the heart rate and stabilize the patient by providing electrical impulses that bypass the blocked pathways in the heart's conduction system.

Other conditions listed, such as pulseless electrical activity, atrial fibrillation, and a heart rate over 100 bpm, do not meet the clinical criteria for transcutaneous pacing. Pulseless electrical activity typically requires CPR and advanced cardiovascular life support measures, while atrial fibrillation is managed differently, focusing on rate control and anticoagulation. A heart rate over 100 bpm may not indicate a need for pacing if the patient remains stable and