Editing Defibrillation (section)

=== Direct current method ===
[[File:Defrib.svg|thumb|A circuit diagram showing the simplest (non-electronically controlled) defibrillator design, depending on the inductor (damping), producing a Lown, Edmark or Gurvich Waveform]]

Early successful experiments of successful defibrillation by the discharge of a capacitor performed on animals were reported by [[Naum Gurvich|N. L. Gurvich]] and G. S. Yunyev in 1939.<ref name="Gurvich" /> In 1947 their works were reported in western medical journals.<ref name="Yunyev" /> Serial production of Gurvich's pulse defibrillator started in 1952 at the electromechanical plant of the institute, and was designated model ИД-1-ВЭИ (''Импульсный Дефибриллятор 1, Всесоюзный Электротехнический Институт'', or in English, ''Pulse Defibrillator 1, All-Union Electrotechnical Institute''). It is described in detail in Gurvich's 1957 book, ''Heart Fibrillation and Defibrillation''.<ref name="Medgiz" />

The first Czechoslovak  "universal defibrillator Prema" was manufactured in 1957 by the company Prema, designed by Dr. Bohumil Peleška. In 1958 his device was awarded Grand Prix at [[Expo 58]].<ref name="Peleška" />

In 1958, US senator [[Hubert H. Humphrey]] visited [[Nikita Khrushchev]] and among other things he visited the Moscow Institute of Reanimatology, where, among others, he met with Gurvich.<ref name="Humphrey-1959" />  Humphrey immediately recognized importance of reanimation research and after that a number of American doctors visited Gurvich. At the same time, Humphrey worked on establishing a federal program in the [[National Institute of Health]]  in physiology and medicine, telling Congress: "Let's compete with U.S.S.R. in research on reversibility of death".<ref name="Humphrey-1962" />

In 1959 [[Bernard Lown]] commenced research in his animal laboratory in collaboration with engineer [[Barouh Berkovits]] into a technique which involved charging of a bank of [[capacitor]]s to approximately 1000 volts with an [[energy]] content of 100–200 [[joule]]s then delivering the charge through an inductance such as to produce a heavily damped sinusoidal wave of finite duration (~5 [[millisecond]]s) to the heart by way of paddle electrodes.  This team further developed an understanding of the optimal timing of shock delivery in the cardiac cycle, enabling the application of the device to [[Heart arrhythmia|arrhythmias]] such as [[atrial fibrillation]], [[atrial flutter]], and supraventricular [[tachycardia]]s in the technique known as "[[cardioversion]]".

The Lown-Berkovits waveform, as it was known, was the standard for defibrillation until the late 1980s. Earlier in the 1980s, the "MU lab" at the University of Missouri had pioneered numerous studies introducing a new waveform called a biphasic truncated waveform (BTE). In this waveform an exponentially decaying DC voltage is reversed in polarity about halfway through the shock time, then continues to decay for some time after which the voltage is cut off, or truncated. The studies showed that the biphasic truncated waveform could be more efficacious while requiring the delivery of lower levels of energy to produce defibrillation.<ref name="patent1" /> An added benefit was a significant reduction in weight of the machine. The BTE waveform, combined with automatic measurement of transthoracic impedance, is the basis for modern defibrillators.{{Citation needed|date=November 2014}}