SHOCK AND ABLATIONS: THERAPIES FOR VENTRICULAR ARRHYTHMIAS

摘要

High-energy electrical shocks are the only effective technique to terminate ventricular fibrillation (VF). Since their approval by the FDA in 1985, implantable cardioverter defibrillators (ICD) have been used to monitor human patients at risk of developing VF and to deliver shocks when life-threatening rhythms are detected.1ICD generators are connected to an electrode that is secured within the right heart chambers. A right ventricular defibrillation coil (RV coil) at the extremity of the electrode, and a superior vena cava coil (SVC coil) positioned 15 to 20 cm more proximally, allow to select various directions for the vector of defibrillation; high-energy shocks can be delivered between the 2 coils, between the RV coil and the generator or between the 2 coils and the generator. In dogs, ICD positioning is critical because the shock of defibrillation must travel through most of the left ventricular muscle to be effective. The generator cannot be placed in the cervical region as it is usually done with pacemakers. Defibrillation has to be programmed between the RV coil and the generator, which is placed subcutaneously on the left side of the thorax.2,3