Defibrillator: An Overview

Topics: Ventricular fibrillation, Heart, Implantable cardioverter-defibrillator Pages: 8 (1693 words) Published: September 23, 2014

An electronic device that administers an electric shock of preset voltage to the heart through the chest wall in an attempt to restore the normal rhythm of the heart during ventricular fibrillation. Defibrillation is a procedure used to treat life threatening conditions that affect the rhythm of the heart such as cardiac arrhythmia, ventricular fibrillation and pulseless ventricular tachycardia. The procedure involves the delivery of an electric shock to the heart which causes depolarisation of the heart muscles and re-establishes normal conduction of the heart’s electrical impulse. The machine used to deliver this therapeutic shock to the heart is called a defibrillator. Defibrillators are key devices in maintaining proper cardiac function. A bit of background in cardiology will aid in the understanding of the role of defibrillators. First, ventricular fibrillation is a cardiac condition where individual heart muscles contract in a random, uncoordinated way. The heart seems to shiver, and blood circulation stops. The application of an electric shock to restore normal heart function is the only way to effectively treat a ventricular fibrillation and prevent death. History

Key milestones occurred in the invention and development of the modern day defibrillator: * In 1899 by French physiologists, Jean Louis Prevost and Frederic Battelli, were able to stop ventricular fibrillation in a dog by applying an electric shock to the animal's exposed heart.

* In 1930, William B. Kouwenhoven, an American electrical engineer at Johns Hopkins University, and colleagues developed a closed-chest defibrillator that sent alternating current (AC) electrical shocks to the heart through electrodes placed on a dog's chest.

* In 1947, Claude Beck, professor of surgery at Case Western Reserve University, first successfully resuscitated a human patient by internal cardiac massage and electrical defibrillation.
* In 1961, American cardiologist Paul Zoll applied AC defibrillation to human patients in 1961.
* In 1962, the direct current (DC) defibrillator was introduced by Lown and Neuman in 1962 provided greater reliability and safety.
* In 1985, an implantable device, called the automatic implantable cardioverter defibrillator (AICD) to stop heart arrhythmias that was invented by Dr. Mieczyslaw Mirowski, of Johns Hopkins University received FDA approval. The device had dual tasks: the defibrillator jolts the heart out of ventricular fibrillation and the cardioverter shocks the heart out of an abnormally fast heartbeat. A heftier power pack is needed and so the battery is implanted in the patient’s abdomen.

The major contribution of defibrillators is that have greatly improved the ability of patients to survive different cardiac conditions (heart surgery, heart attacks, etc.) where the heart can potentially go into ventricular fibrillation.

Since the 1970s, most hospital emergency rooms have been equipped with electric defibrillators, and portable devices have becoming standard equipment for ambulances. A recent medical advance is the growth of automated external defibrillators (AEDs), lightweight, portable, user-friendly devices can be found in police cars, stadiums, etc. These devices can be used with minimal training; specifically, they provide audio instructions and visual prompts to walk the operator through the defibrillating process. Scientific Principle Behind Defribillator

Defribillation is based upon the understanding that contraction of the heart, and the resulting circulation is under the control of electrical conduction system of the heart.

Defibrillation is based upon the understanding that contraction of the heart, and the resulting circulation, is under the control of the electrical conduction system of the heart. The sinoatrial node, (SAN) located within the wall of the right atrium, normally generates electrical impulses that are carried by...
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