Improvement of stimulation and sensing performance of bipolar pacemaker leads

The quality of stimulation electrodes is determined by their pacing and sensing performance. During the past three years experimental efforts demonstrated, that both properties are significantly improved by coating the tips of unipolar leads with titanium nitride due to its high porosity resulting in a significant increase in Helmholtz capacity. However, the stimulation performance of bipolar leads is still poor due to the smooth surface of the indifferent ring electrodes. Therefore this paper deals with the question of suitable ring coating materials. It is shown that sputtered iridium coatings are superior to titanium nitride coatings under anodical polarization, whereas titanium nitride should be used for the cathodically polarized tip only.