What monitoring technique can help identify phrenic nerve proximity during ablation?

High-output pacing is a technique used during catheter ablation procedures that can help identify the proximity of the phrenic nerve, which runs near the right atrium where many ablation procedures take place. By applying a high-output pacing stimulus to the heart tissue, a clinician can provoke rhythmic contractions in the diaphragm if the phrenic nerve is nearby. This allows for real-time feedback about the anatomical relationship between the ablation site and the phrenic nerve, helping to prevent complications associated with nerve damage during the procedure.

Other options, while useful in different contexts of cardiac monitoring, do not provide the same level of anatomical guidance for nerve proximity. Electrocardiogram monitoring is primarily for assessing the heart's electrical activity, and although it is essential in the overall management of atrial fibrillation, it does not provide information about the phrenic nerve's location. Transesophageal echocardiogram offers detailed images of the heart's structures and function but is not tailored for nerve identification. Chest X-ray is useful for evaluating overall chest health but does not provide specific information about the relationship between heart structures and the phrenic nerve. Thus, high-output pacing stands out as the most relevant technique in this context.