A method and system for monitoring phrenic nerve function and preventing phrenic nerve injury during cardiac ablation. The system includes a pacing device operable to transmit stimulation energy to the phrenic nerve through target tissue proximate the phrenic nerve, a plurality of assessment electrodes operable to make comparisons between baseline, real-time, and predetermined threshold values for CMAP signal amplitude and amplitude over time. The processing device may be connected to an ablation console, and the processing device may interrupt or adjust an ablation procedure controlled by the ablation console and/or generate a system alert in response to one of these comparisons, if the comparison indicates phrenic nerve injury. The method includes applying stimulation energy to the phrenic nerve, recording diaphragmatic CMAP signals in response to the stimulation energy, and adjusting an ablation procedure and/or automatically generating a system alert in response to comparisons performed by the processing device.
