Transvenous Implantable Cardioverter-Defibrillator Leads

Transvenous implantable cardioverter-defibrillator (ICD) lead development was an important advance in arrhythmia management. Their evolution has been critical to the wide acceptance of ICDs for the treatment of ventricular arrhythmias and the prevention of sudden cardiac death. Indeed, it is unlikely that the 20-fold increase in annual ICD implants observed during the past 15 years would have occurred without the advent of these leads.1 Compared with their epicardial predecessors, transvenous ICD leads are easier to implant, are less costly, and result in substantially decreased morbidity and mortality.2Article p 2474 Modern ICD leads consist primarily of electrodes, conductors, and insulation, with a fixation mechanism and a connector to attach the lead to the myocardium and the ICD generator, respectively. ICD leads must withstand hundreds of millions of repetitive cardiac cycles, survive in the hostile environment of the human body, and allow high-voltage energy delivery for defibrillation at a moment’s notice. In total, the demands placed on ICD leads are unparalleled among implantable medical devices. Successful resuscitation of a potentially lethal ventricular arrhythmia by an ICD system depends on successful arrhythmia detection and timely delivery of therapy. Both the ICD generator and the lead are critical components of this system. Although ICD generator malfunctions have recently garnered much attention, failure of an ICD lead also can result in significant clinical events.1,3,4 Oversensing can cause inhibition of pacing or inappropriate shocks, and failure to capture, premature battery depletion, or failure to defibrillate also can occur.5Unlike ICD generators, which can be explanted and returned for manufacturer analysis when malfunction is suspected, ICD leads cannot be easily removed, because of the extensive scarring and fibrosis that occurs around the lead in the vasculature and heart. Verification of suspected lead malfunction is uncommon because of the substantial risks of lead …