CARDIAC PACING ELECTRODES

On the surface, the cardiac pacing lead is just a simple cable that co nnects 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 h eart will contract with each stimulus. Thus the pacemaker must deliver a pulse of sufficient voltage and duration to stimulate with a suffic ient safety factor to cope with ally minute-to-minute variations that may occur in daily life. At the same time, it is necessary to use as l ittle current as possible to maintain as long a battery longevity as i s practical. The most common approaches to the problem of reliably del ivering a stimulus with adequate safety margin while decreasing the cu rrent drained from the battery have traditionally centered around elec trode size, materials, surface structure, shape, and more recently, gl ucocorticosteroid sustained release. Relatively little effort has been directed toward optimizing the stimulus waveform for treatment of Bra dy arrhythmias.