O Cameron Health's subcutaneous implantable cardioverter defibrillator (S-ICD), ao contrário dos dispositivos convencionais, não necessita de implante eletrodo transvenoso conferindo uma vantagem naqueles pacientes que não possuem acessos venosos adequados ( eletrodos calibrosos).
O novo dispositivo, liberado inicialmente pela União Europeia e, recentemente, com voto favoravel para liberaçãoFDA após os resultados do ensaio clínico da New England publicado em julho de 2010, possui um eletrodo implantado através do tecido subcutâneo em região paraesternal e um gerador de pulso localizado em porção lateral do tórax, porém, devido a esta configuração, necessita de energia significativamente maior para a terapia do que os dispositivos intra cardíacos convencionais. Outras desvantagens é que o novo CDI não pode ter a função de marcapasso com estímulos contínuos e não trata arritmias com menos de 170 batimentos/min.
O abstract do The New England Journal of Medicine:
Methods First, we conducted two short-term clinical trials to identify a suitable device configuration and assess energy requirements. We evaluated four subcutaneous ICD configurations in 78 patients who were candidates for ICD implantation and subsequently tested the best configuration in 49 additional patients to determine the subcutaneous defibrillation threshold in comparison with that of the standard transvenous ICD. Then we evaluated the long-term use of subcutaneous ICDs in a pilot study, involving 6 patients, which was followed by a trial involving 55 patients.
Results The best device configuration consisted of a parasternal electrode and a left lateral thoracic pulse generator. This configuration was as effective as a transvenous ICD for terminating induced ventricular fibrillation, albeit with a significantly higher mean (±SD) energy requirement (36.6±19.8 J vs. 11.1±8.5 J). Among patients who received a permanent subcutaneous ICD, ventricular fibrillation was successfully detected in 100% of 137 induced episodes. Induced ventricular fibrillation was converted twice in 58 of 59 patients (98%) with the delivery of 65-J shocks in two consecutive tests. Clinically significant adverse events included two pocket infections and four lead revisions. After a mean of 10±1 months, the device had successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia.
Conclusions In small, nonrandomized studies, an entirely subcutaneous ICD consistently detected and converted ventricular fibrillation induced during electrophysiological testing. The device also successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia.
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