Cardiac pacing electrodes

On the surface, the cardiac pacing lead is just a simple cable that connects the pulse generator to the heart. The simple appearance of the lead is very misleading, however. The size, longevity, and features of the pulse generator and the patient's safety depend to a large extent on the performance of the lead. The pacemaker must assure that the heart will contract with each stimulus. Thus the pacemaker must deliver a pulse of sufficient voltage and duration to stimulate with a sufficient safety factor to cope with any minute-to-minute variations that may occur in daily life. At the same time, it is necessary to use as little current as possible to maintain as long a battery longevity as is practical. The most common approaches to the problem of reliably delivering a stimulus with adequate safety margin while decreasing the current drained from the battery have traditionally centered around electrode size, materials, surface structure, shape, and more recently glucocorticosteroid sustained release. Relatively little effort has been directed reward optimizing the stimulus waveform for treatment of Brady arrhythmias.