Cardioversion
Authors: Ivan Cakulev, Igor R. Efimov, Albert L. Waldo
Journal: Circulation (2009)

Simplicity is the ultimate sophistication.-Leonardo da Vinci R ecent years have seen rapid proliferation of ablative and antiarrhythmic therapies for treating various ventricular and supraventricular arrhythmias.Yet cardioversion and defibrillation remain the main modalities to restore normal sinus rhythm.Their simplicity, reliability, safety, and, most important, their efficacy in promptly restoring normal sinus rhythm are unmatched in our current treatment armamentarium. History The Early WorkContemporary cardiology has been significantly affected by the ready availability of this simple method for terminating atrial and ventricular tachyarrhythmias.However, fascination with electricity and its use in biological systems is hardly contemporary.The first capacitor that was able to store electric energy in a glass container was discovered in 1745.It was named the Leyden jar, and its use was shortly thereafter tested in the electrocution of small animals.There is a large body of literature in Italy, France, and England on biological and medical application of electricity dating from the 17th and 18th centuries.Although physicians across Europe started using electricity as an experimental treatment, the earliest recorded scientific approach with the use of electric shocks was that of Peter Abildgaard in 1775. 1 He systematically shocked hens, delivering electric charges in different parts of their body.Electric stimuli applied anywhere across the body of the hen, particularly in the head, could render the animal lifeless, but subsequent shocks delivered to the chest could revive the heart.Abildgaard was only one of the several scientists who studied the effects of electricity on animals.Some reported similar findings, and others could not reproduce his results.However, Luigi Galvani in 1781 first clearly described the link between electricity and its presence in biological systems. 2 He was the first to use the term animal electricity, coined after his famous experiments in which he caused the legs of a skinned frog to kick when touched with a pair of scissors during an electric storm.The recognition of electricity in living organisms sparked intense interest and excite-ment and led to application of electricity to revive the dead.Possibly the first description of successful resuscitation with the use of electric shock was reported by Charles Kite in 1788, when a 3-year-old girl, a victim of a fall, was shocked through the chest by an electric generator and a Leyden jar by a Mr Squires of London. 3A similar report by Fell appeared in Gentlemen's Magazine in 1792, with the description of this first prototype of a modern defibrillator (Figure 1).In 1792, the British scientist James Curry published a review of resuscitation cases and recommended that "moderate shocks be passed through the chest in different directions in order, if possible, to rouse the heart to act." 4 Several other successful attempts at resuscitation led the Royal Humane Society in England to publish a report in 1802 suggesting the application of electric shock to distinguish "real from apparent death" and praising the potential of electric resuscitation.Scientists at that time were unaware that, at least in some cases, revival with electricity was perhaps due to successful termination of ventricular fibrillation (VF).Ludwig and Hoffa were the first to describe this arrhythmia in 1849 when they observed bizarre and chaotic action of the ventricles when exposed directly to electric current. 5The nature of this arrhythmia was subjected to speculation.Neurogenic theory that explained VF as a consequence of abnormal generation and conduction within the neural network was favored.A French neurophysiologist, Edme Vulpian, coined the term fibrillation and first suggested that the heart itself was responsible for originating and sustaining this irregular rhythm that results in mechanical disarray. 6n 1889, John McWilliam of Aberdeen, Scotland, was the first to suggest that VF, and not cardiac standstill, was the mechanism of sudden death in humans. 7Previously, he had experimented with mammalian animal hearts and was able to induce VF by applying electricity directly to the heart. 8Two physicians, Jean-Louis Prevost, a former trainee of Vulpian, and Frederic Battelli, worked together at the University of Geneva, Switzerland, on the mechanism of electrically induced VF. 9 They confirmed the observations of Ludwig, Vulpian, and McWilliam in 1899 by showing that a small amount of electricity delivered across the chest can induce VF. 9 It is fascinating that their secondary observation, mentioned only in a footnote, that larger electric shocks success-