ACTIVATED PYROLYTIC CARBON TIP PACING LEADS - AN ALTERNATIVE TO STEROID-ELUTING PACING LEADS

Pyrolytic carbon technology is known for ifs excellent mechanical prop erties and electrical conductivity; it is particularly biocompatible a nd does not require high production costs. The Sorin S100/4 lead is a ventricular passive fixation lead with a hemispherical electrode surfa ce area of 4 mm(2); the stimulating tip is made of a graphite core coa ted by a thin activated pyrolytic carbon layer. We evaluated the acute and medium-term performance of-the unipolar version of this lead in 6 5 patients. At implantation, pacing threshold (at 0.5 ms) was 0.26 +/- 0.08 V; pacing impedance (at 5 V and 0.5 ms) was 537 +/- 94 Omega and R wave amplitude was 15.0 +/- 5.5 mV. No lead related complications ( dislodgment, perforation, exit block, etc.) occurred in any patient; o ne patient presented with a wire fracture after 26 months,due to subcl avian crush syndrome. Follow-up procedures were performed at 1 week, a nd 2-, 10-, 18-, and 30-months postimplant. Since the leads were conne cted to pacemakers from different manufacturers, either voltage or dur ation thresholds were measured. In approximately two thirds of the pat ients, with an output of 2.5 V, a mean duration threshold of 0.26 +/- 0.13 ms at 1 week, 0.12 +/- 0.08 ms at 2 months, 0.11 +/- 0.06 ms at 1 0 months, 0.09 +/- 0.06 ms at 18 months, and 0.07 +/- 0.03 ms at 30 mo nths, was measured. In the remaining one-third of the patients, a comp arable voltage threshold trend was measured. The mean pacing impedance showed a transient drop at 1 week, and then increased to a plateau of about 600 Omega reached after 10 months. No sensing defect occurred i n any patient; Our data show good acute and intermediate-term results of the S100/4 lead; the early rise in threshold was remarkably blunted . Activated pyrolytic carbon tip leads might therefore be considered a s a possible, inexpensive alternative to steroid-eluting leads.