discovered that small electrical shocks could induce ventricular fibrillation in dogs, and that larger charges would reverse the condition. in 1933, dr. albert hyman, heart specialist at the beth davis hospital of new york city and c. henry hyman, an electrical engineer, looking for an alternative to injecting powerful drugs directly into the heart, came up with an invention that used an electrical shock in place of drug injection. this invention was called the hyman otor where a hollow needle is used to pass an insulated wire to the heart area to deliver the electrical shock. the hollow steel needle acted as one end of the circuit and the tip of the insulated wire the other end. whether the hyman otor was a success is unknown. the external defibrillator, as it is known today, was invented by electrical engineer william kouwenhoven in 1930. kouwenhoven studied the relationship between electric shocks and their effects on the human heart when he was a student at johns hopkins university school of engineering. his studies helped him invent a device to externally jump start the heart. he invented the defibrillator and tested it on a dog, like prévost and batelli. the first use on a human was in 1947 by claude beck, professor of surgery at case western reserve university. beck's theory was that ventricular fibrillation often occurred in hearts that were fundamentally healthy, in his terms "hearts that are too good to die", and that there must be a way of saving them. beck first used the technique successfully on a 14-year-old boy who was having his breastbone separated from his ribs because of a congenital growth disorder, causing breathing problems. the boy's chest was surgically opened, and manual cardiac massage was undertaken for 45 minutes until the arrival of the defibrillator. beck used internal paddles on either side of the heart, along with procainamide, an antiarrhythmic drug, and achieved return of a perfusing cardiac rhythm. these early defibrillators used the alternating current from a power socket, transformed from the 110–240 volts available in the line, up to between 300 and 1000 volts, to the exposed heart by way of "paddle" type electrodes. the technique was often ineffective in reverting vf while morphological studies showed damage to the cells of the heart muscle post-mortem. the nature of the ac machine with a large transformer also made these units very hard to transport, and they tended to be large units on wheels. closed-chest method until the early 1950s, defibrillation of the heart was possible only when the chest cavity was open during surgery. the technique used an alternating voltage from a 300 or greater volt source derived from standard ac power, delivered to the sides of the exposed heart by "paddle" electrodes where each electrode was a flat or slightly concave metal plate of about 40 mm diameter. the closed-chest defibrillator device which applied an alternating voltage of greater than 1000 volts, conducted by means of externally applied electrodes through the chest cage to the heart, was pioneered by dr v. eskin with assistance by a. klimov in frunze, ussr (today known as bishkek, kyrgyzstan) in the mid-1950s. the duration of ac shocks was typically in the range of 100–150 milliseconds. direct current method 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 n. l. gurvich and g. s. yunyev in 1939. in 1947 their works were reported in western medical journals. 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. 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. 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. 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". 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 capacitors to approximately 1000 volts with an energy content of 100–200 joules then delivering the charge through an inductance such as to produce a heavily damped sinusoidal wave of finite duration (~5 milliseconds) 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 arrhythmias such as atrial fibrillation, atrial flutter, and supraventricular tachycardias 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. 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. portable units wall-mounted emergency defibrillator a major breakthrough was the introduction of portable defibrillators used out of the hospital. already peleška's prema defibrillator was designed to be more portable than original gurvich's model. in soviet union, a portable version of gurvich's defibrillator, model дпа-3 (dpa-3), was reported in 1959. in the west this was pioneered in the early 1960s by prof. frank pantridge in belfast. today portable defibrillators are among the many very important tools carried by ambulances. they are the only proven way to resuscitate a person who has had a cardiac arrest unwitnessed by emergency medical services (ems) who is still in persistent ventricular fibrillation or ventricular tachycardia at the arrival of pre-hospital providers. gradual improvements in the design of defibrillators, partly based on the work developing implanted versions (see below), have led to the availability of automated external defibrillators. these devices can analyse the heart rhythm by themselves, diagnose the shockable rhythms, and charge to treat. this means that no clinical skill is required in their use, allowing lay people to respond to emergencies effectively. waveform change until the mid 90s, external defibrillators delivered a lown type waveform (see bernard lown) which was a heavily damped sinusoidal impulse having a mainly uniphasic characteristic. biphasic defibrillation alternates the direction of the pulses, completing one cycle in approximately 12 milliseconds. biphasic defibrillation was originally developed and used for implantable cardioverter-defibrillators. when applied to external defibrillators, biphasic defibrillation significantly decreases the energy level necessary for successful defibrillation, decreasing the risk of burns and myocardial damage. ventricular fibrillation (vf) could be returned to normal sinus rhythm in 60% of cardiac arrest patients treated with a single shock from a monophasic defibrillator. most biphasic defibrillators have a first shock success rate of greater than 90%. implantable devices a further development in defibrillation came with the invention of the implantable device, known as an implantable cardioverter-defibrillator (or icd). this was pioneered at sinai hospital in baltimore by a team that included stephen heilman, alois langer, jack lattuca, morton mower, michel mirowski, and mir imran, with the help of industrial collaborator intec systems of pittsburgh. mirowski teamed up with mower and staewen, and together they commenced their research in 1969. however, it was 11 years before they treated their first patient. similar developmental work was carried out by schuder and colleagues at the university of missouri. the work was commenced, despite doubts amongst leading experts in the field of arrhythmias and sudden death. there was doubt that their ideas would ever become a clinical reality. in 1962 bernard lown introduced the external dc defibrillator. this device applied a direct current from a discharging capacitor through the chest wall into the heart to stop heart fibrillation. in 1972, lown stated in the journal circulation — "the very rare patient who has frequent bouts of ventricular fibrillation is best treated in a coronary care unit and is better served by an effective antiarrhythmic program or surgical correction of inadequate coronary blood flow or ventricular malfunction. in fact, the implanted defibrillator system represents an imperfect solution in search of a plausible and practical application." the problems to be overcome were the design of a system which would allow detection of ventricular fibrillation or ventricular tachycardia. despite the lack of financial backing and grants, they persisted and the first device was implanted in february 1980 at johns hopkins hospital by dr. levi watkins jr. assisted by vivien thomas. modern icds do not require a thoracotomy and possess pacing, cardioversion, and defibrillation capabilities. the invention of implantable units is invaluable to some people with regular heart problems, although they are generally only given to those people who have already had a cardiac episode. people can live long normal lives with the devices. many patients have multiple implants. a patient in houston, texas had an implant at the age of 18 in 1994 by the recent dr. antonio pacifico. he was awarded "youngest patient with defibrillator" in 1996. today these devices are implanted into small babies shortly after birth. society and culture as devices that can quickly produce dramatic improvements in patient health, defibrillators are often depicted in movies, television, video games and other fictional media. their function, however, is often exaggerated with the defibrillator inducing a sudden, violent jerk or convulsion by the patient. the pad placement is also shown wrong, along with sudden rising of patient to large height when shock is given. in reality, while the muscles may contract, such dramatic patient presentation is rare. similarly, medical providers are often depicted defibrillating patients with a "flat-line" ecg rhythm (also known as asystole). this is not normal medical practice, as the heart cannot be restarted by the defibrillator itself. only the cardiac arrest rhythms ventricular fibrillation and pulseless ventricular tachycardia are normally defibrillated. the purpose of defibrillation is to depolarize the entire heart all at once so that it is synchronized, effectively inducing temporary asystole, in the hope that in the absence of the previous abnormal electrical activity, the heart will spontaneously resume beating normally. someone who is already in asystole cannot be helped by electrical means, and usually needs urgent cpr and intravenous medication (and even these are rarely successful in cases of asystole). a useful analogy to remember is to think of defibrillators as power-cycling, rather than jump-starting, the heart. there are also several heart rhythms that can be "shocked" when the patient is not in cardiac arrest, such as supraventricular tachycardia and ventricular tachycardia that produces a pulse; this more-complicated procedure is known as cardioversion, not defibrillation. in australia up until the 1990s it was relatively rare for ambulances to carry defibrillators. this changed in 1990 after australian media mogul kerry packer had a cardiac arrest due to a heart attack and, purely by chance, the ambulance that responded to the call carried a defibrillator. after recovering, kerry packer donated a large sum to the ambulance service of new south wales in order that all ambulances in new south wales should be fitted with a personal defibrillator, which is why defibrillators in australia are sometimes colloquially called "packer whackers".