High impedance leads and safety margin. Electrical considerations based on a simplified expression of the 'paradigm'

Abstract

For physicians who are not familiar with the electrical basis of cardiac stimulation, high impedance leads previously (10 years ago) considered as bad electrodes (high voltage) are now considered as the 'epitome' of lead technology (low energy drain): clearly impedance is not a good parameter for characterizing the qualities of a pacing lead. Using a simplified approach to the electrostimulation 'paradigm', it is easy to establish that modern high impedance leads are in fact high current density leads and high efficiency leads (better description). It is also possible to establish that routine programming of the safety margin at 100% above threshold parameters is associated with a decrease in the penetration of the electric field according to the reduction of the cathode surface area. For safety and energy saving, a small tip electrode could be combined with a low polarization surface treatment and a reduction in fibrosis development between electrode and myocardium. © 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.