HIGH-INCIDENCE OF ISOLATOR FRACTURES IN T RANSVENOUS IMPLANTED CARDIOVERTER DEFIBRILLATORS/

With the growing complexity of transvenous ICD-lead systems the incide nce of lead complications might increase in comparison to usual pacema ker leads. The incidence of insulation defects of transvenous leads wa s determined during a mean follow-up time of 23.8 +/- 10.9 months. Amo ng 130 transvenous ICD-patients, eight insulation-breaks in seven pati ents (6 %) could be identified after a mean follow-up of 28 +/- 13 mon ths. After a follow-up period of 12 months no lead defect was identifi ed, after 24 months 96.3 +/- 1.8 % of all transvenous leads were free of complications, after 36 months 87.9 +/- 6 % and after 48 months in 61.2 +/- 18.7 % of all leads no isolator fracture was found. In seven cases an operative revision was required. All insulation-defects were exclusively found in abdominaly implanted silicone lead-systems type E ndotak/CPI (Cardiac Pacemakers, Inc., USA): isolator fractures occurre d in 12 % of all Endotak leads used, 19 % of the Endotak C models 62, 64, 72 and 74 were affected. In none of 66 implanted Transvene lead sy stems (Medtronic, Inc., USA) were isolator defects found. In six patie nts the proximal part of the sensing lead near the device was affected . All of these patients experienced potentially harmful repetitive dev ice discharges. In one patient during elective ICD-replacement an isol ation break of the proximal shock electrode was found, in another pati ent between the proximal and distal shack-electrode. Despite regular f ollow-ups with impedance-measurements, only in one case was the insula tion break foreseeable. Stored electrograms were helpful to disclose i nsulation defects. With increasing age of the transvenous lead systems a growing number of insulation defects has to be expected. Especially the isolators of the first Endotak C models 60-74 seem to create majo r problems with increasing age.