PAC on His

From Ask Dr Wiki

Introduction

PAC on His is a maneuver that can be used to demonstrate that the atrium is a part of the tachycardia circuit which will help diagnose an Antidromic Tachycardia when faced with a Wide Complex Tachycardia.

How to Perform

To perform this maneuver you must deliver the PAC near the atrial insertion of the accessory pathway. You should set the stimulator to sense off of the High Right or CS catheter and deliver the PAC just prior to the atrial signal on the septal atrial channel. You must time off of the septal atrial signal instead of the His, because the His signal is invisible because it is buried in the ventricular electrogram in an Antidromic Tachycardia. If the PAC advances the ventricle when timed just prior to the septal Atrial electrogram, then the advancement of the ventricle can only have occurred over an accessory pathway. This maneuver is the counterpart to the PVC on His Maneuver used in Narrow Complex Tachycardias.

Image:PAC on His 2.tif Image:PAC on His.tif