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Defibrillator

Defibrillation/cardioversion is a technique employed to counter arrhythmic heart conditions including some tachycardias in the atria and/or ventricles. Cardiac arrest and ventricular fibrillation are life-threatening medical conditions that may be treated with external defibrillation. Defibrillators are devices for providing life-saving electrical shock therapy to persons experiencing an irregular heart beat, such as Ventricular Fibrillation (VF). A defibrillator provides an electrical shock to the heart, in order to convert the irregular heart beat to a normal sinus rhythm. Two kinds of defibrillators are presently available: internal defibrillators which are implanted subcutaneously in a patient together with leads extending through the veins into the cardiac chambers, and external defibrillators which are attached (usually temporarily) to the patient. External defibrillators are used in most instances in case of an emergency, for example, when a patient has either suffered cardiac arrest or when a cardiac arrest is imminent. External defibrillation is a treatment process in which an electrical waveform, or an electrical defibrillation pulse, is applied to the cardiac muscle resulting in the cessation of rapid uncoordinated contractions of the heart. Following external defibrillation, the heart is restored to its normal beating state. External defibrillation treatment is commonly administered with an automated external defibrillator that includes heart rhythm sensors, current generating circuitry and electrode pads for delivering the electrical defibrillation pulse. Many external defibrillators are portable. Portable external defibrillators may be used in hospitals and outside hospital settings as well. Paramedics, emergency medical technicians and police officers, for example, may carry portable external defibrillators in their vehicles. In addition, automated external defibrillators may be available in public venues such as airports, health clubs and auditoriums. Portable external defibrillators are compact and lightweight. External defibrillators may be manually operated, as are typically used in hospitals by medical personnel or may be semi-automatic, semi-automated, fully automatic, or fully automated devices, where they can be used in any location where an unanticipated need may occur. An automatic implantable cardioverter defibrillator (AICD) or implantable cardioverter defibrillator (ICD) detects ventricular fibrillation and delivers a series of countershocks of sufficient energy to terminate the fibrillation. Such an ICD utilizes an electrode system either attached to the outer surface of the heart by means of a large surface area patch electrode, or inserted transvenously into or near the heart. Such an ICD system may be combined with a pacemaker function. In general, implantable defibrillators deliver a first pulse at a first energy level upon detecting fibrillation and, if the fibrillation is not stopped, deliver additional pulses at increasing energy levels until the fibrillation is stopped or the programmed progression of pulses has been exhausted.

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