Defibrillator

A defibrillator (defib for short) is a medical device that treats life-threatening cardiac arrhythmias like ventricular tachycardia and ventricular fibrillation. These devices have saved the lives of thousands of people and are being sought by public authorities and the general population for greater public access.


The effectiveness of applying an electrical shock to the heart was first seen in 1899 when two physiologists from Switzerland named John Louis Prevost and Frederick Batelli used small doses of electricity to reverse ventricular fibrillation in canines. It wasn’t until 1947 when a surgeon, Claude Beck, used one of the first defibrillator machines on a 14-year-old boy with a congenital chest defect. Since then much has changed in the development and effectiveness of defibrillators. Defibrillators have evolved to be much smaller in size and deliver smaller and more effective doses of electricity to patients. Early defibrillator units were found to damage the cell walls of the heart due to their high electrical current.

Between 1950 and 1980 were perhaps the most decisive years for the development of the defibrillator to what it is known as today. Before the mid-1950s, the only way to apply defibrillation to a patient was when their chest cavity was open; however, this changed when Dr. V. Eskin and A. Klimov of the USSR developed a “closed chest method” of defibrillation. There are six different types of defibrillators used in cases of cardiac arrhythmia; manual external defibrillators, manual internal defibrillators, automated external defibrillators, semi-automated external defibrillators, implantable cardioverter defibrillators, and wearable cardioverter defibrillators. A manual external defibrillator and a manual internal defibrillator are almost exclusively available in hospitals and operating rooms because they require advanced operations and knowledge by the user (medical/hospital staff) in order to be effective.

The invention of the automated external defibrillator allowed for greater ease of use by medical professionals and even those not trained in defibrillation. Using computer sensing technology, an automated external defibrillator will analyze a patient’s heartbeat for about 10 to 20 seconds and diagnose any cardiac arrhythmia. These defib devices make it fast and safe for bystanders and on-site medical professionals to administer a dose of electricity to an affected patient. Generally speaking, they are called “automated” due to their almost hands-free operation and computer guidance. Manual defibrillators require intervention by trained medical staff to diagnose and deliver an electric shock. Some automated external defibrillators allow for intervention by a clinician to manually override the AEDs procedures; these types of units are typically called semi–automated external defibrillators.

The creation of the implantable cardioverter defibrillator has since paved the way for future defibrillation technologies. An implantable cardioverter defibrillator (ICD) is a small electrical medical device that is surgically embedded near the left pectoral region of a patient’s body, whom previously has suffered myocardial infarction. Before a patient receives an implantable cardioverter defibrillator, or if the patient is not able to receive one, they may be equipped with a wearable cardioverter defibrillator. This external device is like a cross between an AED and an ICD; they allow patients to have immediate access to defibrillation therapy by being equipped around patient’s waist region. Electrodes are still needed near the heart for this type of device (as with all other defibrillators) and are usually placed on the middle back region of the patient. Typically in other defibrillator devices, one electrode is placed on the right side of the chest directly below the clavicle while another electrode is placed on the left below the heart; alternatively, one electrode can be placed over the heart and on the lower back. The former placement scheme is often used for immediate defibrillation, especially when not in a hospital setting where the latter placement is typically used on long term sufferers of cardiac illness.

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