Abrasions of the outer silicone insulation of endocardial leads in their intracardiac part: a new mechanism of lead-dependent endocarditis

The aim of the study was to identify and characterize the morphology of abrasions and to establish the frequency of the phenomena and their association with infective endocarditis (IE). A total of 212 endocardial leads removed from 141 consecutive patientsdue to IE (32), pocket infection (37), and non-infective indications (72)were analysed with a stereomicroscope and a scanning electron microscope. The presence of abrasions in the intracardiac part (IP) of the atrial (P 0.01) and ventricular (P 0.00002) leads, regardless of its advancement, was strongly associated with IE. There were associations between abrasions in the IP of the ventricular (P 0.00002) and atrial (P 0.005) leads and two or more implanted endocardial leads. In atrial leads, there was an association between the presence of any abrasion and passive fixation (P 0.05), dwell time (P 0.05), and number of procedures until removal (P 0.006). The abrasions were classified into three levels of degradation under two subtypes according to the morphology observed with a stereomicroscope. The third level of degradation was the most frequently observed in the IP of the leads. The abrasion of the outer insulation in the IP of silicone leads was significant regardless of the level of degradation and is associated with IE. The abrasions observed in the IP of the leads were similar to those observed in the intravenous and pocket parts, with predomination of the third level of degradation. There was an association between the presence of any abrasion in the IP of the leads and the number of leads, and in the case of atrial leads between abrasions and fixation type, dwell time, and number of procedures until explantation.