defibrillator

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Related to automatic implanted ventricular defibrillator: automatic implanted cardioverter defibrillator

defibrillator,

device that delivers an electrical shock to the heart in order to stop certain forms of rapid heart rhythm disturbances (arrhythmiasarrhythmia
, disturbance in the rate or rhythm of the heartbeat. Various arrhythmias can be symptoms of serious heart disorders; however, they are usually of no medical significance except in the presence of additional symptoms.
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). The shock changes a fibrillation to an organized rhythm or changes a very rapid and ineffective cardiac rhythm to a slower, more effective one. In a typical hospital defibrillator, voltage stored by the defibrillator pushes electrical current through the chest to deliver a muscle-contracting jolt to the heart; the current is transmitted by means of electrodes or paddles placed on the chest. Automated external defibrillators are now available for use by persons with minimal medical training in emergencies when medical professionals are unavailable, and miniaturization has led to the development of the implanted internal defibrillator (also called an internal cardioverter). In the latter a microcomputer uses an electrode to monitor the heartbeat. Upon detecting a minor arrhythmia, it activates a built-in conventional pacemakerpacemaker, artificial,
device used to stimulate a rhythmic heartbeat by means of electrical impulses. Implanted in the body when the heart's own electrical conduction system (natural pacemaker) does not function normally, the battery-powered device emits impulses that trigger
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 to restabilize the heart's rhythm. If that fails, it delivers a small defibrillating electrical shock to the heart. In an extreme case, it resorts to a far stronger shock to reset the heart rate.

Defibrillator

 

an apparatus designed to eliminate the major impairment of cardiac activity manifested in separate contractions at different times of individual muscle fibers of the cardiac muscle (fibrillation).

In this condition the heart cannot work efficiently. Cardiac activity is not restored spontaneously during fibrillation. The most effective means to stop fibrillation is to feed a single shortterm (0.01 second) electrical impulse created by discharge of the condenser in the defibrillator to the heart muscle (open or through the thorax). Various models of defibrillators (the ID-VEI-1 and ID-66T) have been built in the USSR. The impulses generated by these defibrillators have a less damaging effect on the heart than the apparatus of other systems. A voltage of 1.5-2.5 kilowatts is used for defibrillation on an open heart (during operations), and a voltage of 4-7 kilowatts is used with an unopened thorax.

L. E. MANEVICH

defibrillator

[dē′fib·rə‚lād·ər]
(medicine)
An electronic instrument used for stopping fibrillation during a heart attack by applying controlled electric pulses to the heart muscles.
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