title: Clinical experience with downsized lower energy output implantable cardioverter defibrillators. Ventak Mini II Clinical Investigators.
abstract: OBJECTIVE
  Technical improvements in cardioverter defibrillators technology has resulted in decrease in can size coupled with improved electrodes technology. A decrease in maximum energy output allows further decrease in device size. The aim of this study was to evaluate the feasibility of a single lead transvenous implant employing a downsized cardioverter-defibrillator (volume 59 cm3), with a related decrease in maximum energy output (29-31 joules as stored energy and 25-27 joules as delivered energy).
  
  
  RESULTS
  Fifty-five patients with ventricular tachyarrhythmias were enrolled in 17 European institutions for implantation. At implantation step-down defibrillation threshold (DFT) was determined and the device was implanted only if a safety margin > or =10 joules was maintained between DFT and maximum programmable output. Implantation was performed in 54 of the 55 referred patients (98%) in a single electrode-device configuration. Step-down DFT testing was performed in 44 patients (43 finally implanted) and DFT was 7.77+/-4.41 joules (range 3-20). In 20 of the tested patients (45%) DFT was < or =5 joules, in 26 patients (59%) was < or =8 joules and in 34 patients (77%) it was < or =10 joules. No differences were found in DFT comparing patients with left ventricular ejection fraction < or = or >40% or patients treated or not with antiarrhythmic drugs or beta-blockers. Mean implant duration was 85+/-34 min.
  
  
  CONCLUSIONS
  Employing a downsized cardioverter defibrillator, successful transvenous implantation can be achieved in 98% of the patients, with maintenance of adequate defibrillation safety margins despite a reduction in stored energy to 29 joules.
authors.affiliation: Institute of Cardiology, University of Bologna, Italy. cardio1@almadns.unibo.it
authors.forename: G
authors.initials: G
authors.lastname: Boriani
authors.forename: L
authors.initials: L
authors.lastname: Frabetti
authors.forename: M
authors.initials: M
authors.lastname: Biffi
authors.forename: L
authors.initials: L
authors.lastname: Sallusti
mesh_terms: D000328:Adult; D000368:Aged; D017147:Defibrillators, Implantable / Q000592:standards; D004562:Electrocardiography; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D019919:Prosthesis Implantation; D012189:Retrospective Studies; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome