Electrical ventricular defibrillation.

Ventricular fibrillation is the condition in which all of the muscle fibers in the ventricles of the heart contract and relax randomly and do not propel blood from the heart. This condition, which is the major cause of sudden death from a heart attack, can be reversed by passage of a single pulse of current through the heart using electrodes applied to the chest wall; this technique is known as ventricular defibrillation. World-wide clinical experience has shown that with existing defibrillators, successful defibrillation of subjects weighing over 100 kg is infrequent. It should not be concluded, however, that defibrillation cannot be achieved in such subjects. To illustrate this point, data will be presented to show that it is possible to establish a dose concept in which the output required from a defibrillator can be specified in terms of the weight of the subject. This dose concept evolved slowly from studies reported by investigators in various countries. For example, the present-day techniques of ventricular defibrillation are due to the investigations of researchers all over the world. Prevost and Battelli (1898) in Switzerland first showed that electric current can both induce ventricular fibrillation and achieve defibrillation. The studies of Kouwenhoven in the 1930's in the USA showed that 60 Hz alternating current can be used for defibrillation. The first human defibrillations in 1947 and 1952 used this type of current; these studies were reported by Beck and Zoll in the USA. The present-day technique for defibrillation derives from the animal studies reported by Gurvich and Yuniev 1946 in Russia. Finally, Lown et al. in the early 1960's applied the technique to man. Exciting new developments are underway in ventricular defibrillation. Not only are higher output defibrillators beginning to appear, but automatic and fully implantable defibrillators are being involved. In this paper, the present state of the art of defibrillation will be reported and future trends will be described.