Incidence of Arrhythmias in the Dog Following Transthoracic Ventricular Defibrillation with Unidirectional Rectangular Stimuli

Abstract

The incidence of the various types of arrhythmia induced by defibrillation in anesthetized dogs that had had continuous ventricular fibrillation for 30 seconds was studied as a function of the current strength and the duration of the unidirectional rectangular pulse used to terminate the fibrillation. Shocks at 10, 20, 40, 80, and 100 amp with durations in the range of 80 fisec through 64 msec were used. At any given energy level the incidence of induced arrhythmias was much larger for the 40-, 80-, and 100-amp shocks than for the 10-and 20-amp shocks. At 10 and 20 amp, the incidence of induced arrhythmias increased with increasing energy content. Premature ventricular contractions were observed at nearly all levels of energy and current, in contrast to other types of arrhythmias that appear to be strongly related to energy content or current amplitude or both. ADDITIONAL KEY WORDSclosed-chest defibrillation countershock energy content of shock heart block premature atrial contraction premature ventricular contraction paroxysmal tachycardia idioventricular contraction• Electric shock can both induce and terminate cardiac arrhythmias and it is desirable to terminate the unwanted arrhythmias without at the same time introducing other serious arrhythmias. Peleska has published detailed studies concerning arrhythmias that follow From the

The Role of an Engineering Oriented Medical Research Group in Developing Improved Methods and Devices for Achieving Ventricular Defibrillation: The University of Missouri Experience

“…16 January, Part I 1993 SGHUDER cess figures substantially independent of animal weight, another 600-episode series [50 A, 4-msec shocks when animals were 100 kg) failed to support our hypothesis that percent success would be independent of body weigbt. Despite an element of ambiguity represented by our experimental results, we continue to believe that the scaling scheme outlined above is informative and probably the best currently availahle.…”

“…In one sense, it started for us on a sidewalk as I waited for a shuttle bus to return me to my motel or hotel room following an afternoon session of the American Heart Association meeting in Dallas (November [13][14][15][16]1969). As I waited, I reviewed possible projects for future work and among them was the automatic implantable defibrillator!…”

“…PAGE, Vol. 16 January, Part I 1993 SCHUDER Two months from conception to quite adequate performance in an experimental animal sounds like an incredibly rapid pace for any new electrophysiological device development project. But then, the effort was really based on a decade of prior defibrillation research and decades of experience in working with relevant electronic circuitry.…”

The effects of biphasic waveform design on post-resuscitation myocardial function

“…Studies often cited to support this notion, however, have either failed to provide supporting data (15) or have not controlled peak current independent of energy (16), leaving the two variables confounded and thus preventing separation of cause and effect. One study that carefully controlled energy independent of peak current was reported by Stoeckle et al (17) in 1968. Their data, from experiments with rectangular monophasic defibrillation pulses, indicate that pulses with peak current below a critical level (40 amperes in their canine model) exhibit a rate of post-shock complication (arrhythmia) independent of current but increasing with energy.…”

Myocardial injury and induction of arrhythmia by direct current shock delivered via endocardial catheters in dogs.

“…16,17 This study was therefore designed to assess the longterm effects of DC shock delivered through an endocardial catheter on regional structure, function, and cardiac rhythm of the canine left ventricle.…”