Implantable cardioverter defibrillator lead technology: improved performance and lower defibrillation thresholds

The performance of an ICD system depends, in part, on the effectiveness with which the lead system functions. Engineering trade-offs are made during the design of a lead to optimize one or more performance characteristics: e.g., lead handling, fatigue life, size, and optimized therapy delivery. To assure low defibrillation thresholds, careful attention must be taken during the design process to prevent these trade-offs from hampering the lead's therapy effectiveness. Four basic design rules are described that capture many of the engineering concepts that will enhance a lead's efficacy: (1) minimize electrode pullback, (2) deliver current to the apex, (3) minimize energy loss in the lead, and (4) use large, efficient electrodes. These rules speak to optimizing delivery of current to the heart and efficiency of the lead and electrode interface. When the lead performs its function well, the complete ICD system of the heart, lead, and implantable pulse generator will provide optimal safety margins for device implant and an increased number of patients that can be implanted with a single-lead system.