Implantation techniques of antitachycardia devices

Implantation of a defibrillator may be by a mixed technique of transvenous leads and subcostal thoracotomy. An alternative approach is placement of all defibrillator leads and possible pacemaker leads via median sternotomy. All sensing leads, either for a defibrillator or a pacemaker, should be bipolar to provide maximal rejection of interference signals. Interpretation of the electrogram requires analysis of the pathologic electrogram to distinguish it from the "normal" electrogram for that patient and may require several leads to determine the activation sequence which will allow diagnosis of a tachycardia in a fashion similar to that performed by a human observer.