Pacemaker Intraoperative complications
Advanced, Basic Sciences
The main concern is electromagnetic interference (EMI) from electrocautery (especially monopolar), evoked potential monitors, nerve stimulator, external defibrillation, radiofrequency ablation, and extracorporeal shockwave lithotripsy. EMI can be interpreted as intrinsic cardiac signal. This can lead to inappropriate inhibition leading to pathologic bradycardia, or oversensing leading to pathologic tachycardia.
There is a concern for R on T phenomenon, especially during lithotripsy. According to the 2011 ASA practice advisory, the atrial pacing should be disabled prior to the procedure.
Radiofrequency ablation when in proximity to the pacer leads can cause a significant drop in the resistance; therefore, the advisory recommends avoidance of direct contact between ablation catheter and pacer leads or the pulse generator.
Electroconvulsive therapy (ECT) can lead to transient electrocardiographic changes, such as increased P-wave amplitude, altered QRS shape, T-wave and ST abnormalities. Thus the advisory recommends comprehensive interrogation of the pacer/AICD prior and after ECT, with ICD function disabled for shock therapy. It is recommended that the care team make preparation for treatment of ventricular dysrhythmias caused by the hemodynamic changes of ECT. Patient may require a temporary pacing system during the shock therapy, or have the pacer/AICD programmed to asynchronous mode to avoid myopotential inhibition.
During emergency defibrillation or cardioversion, the current can flow through the pulse generator and lead system. Therefore, the advisory recommends positioning the defibrillation or cardioversion pads or paddles as far away as possible from the pulse generator.