Clinical applications of external pacing: a renaissance?

It is nearly 40 years since the first reports of noninvasive external pacing for Stokes-Adams syncope. Despite the ease and safety, this method of pacing has yet to flourish despite a recent interest by several authors. At present, external pacing seems best suited for temporary pacing situations that arise as an emergency or for purely prophylactic indications. External pacing is the preferred method of pacing recommended in the advanced cardiac life support guidelines. However, most emergency room and prehospital cardiac arrest trials have not shown any significant benefit from early application of external pacing. The indications have been broadened to include symptomatic bradycardia and termination of some ventricular tachycardias. It may be useful for the termination of AV reciprocating tachycardia and AV nodal reentrant tachycardia. There is a vision that external pacing may be used for serial electrophysiological testing of antiarrhythmic agents. However, there is little data in this regard. More importantly, the external pacing thresholds must be reduced further to allow for sophisticated pacing protocols to be implemented. For practical purposes, external pacing does not capture the atrium. Since the left atrium is easily captured by esophageal pacing, it is likely that noninvasive external pacing will be combined with transesophageal pacing to perform noninvasive electrophysiological testing. The future for external pacing remains in limbo because of the discomfort associated with skeletal muscle contraction. If technical advances can reduce or eliminate this problem, then external pacing may find broader application for bradycardia and tachycardia.