Ultrastructural injury to chick myocardial cells in vitro following "electric countershock".

Abstract

We studied the structural alterations that follow the application of currents similar to those used in clinical electric countershock procedures in cultured chick myocardial cells. Myocardial cells 48 hours in culture were subjected to electric field stimulation. The cells then were fixed for electron-microscope examination 30 seconds postshock. The ultrastructural alterations that appeared after an 80 V/cm shock included the appearance of >25% of the mitochondria per cell in the "condensed" configuration and mitochondria with swirled or tubular cristae. Large-amplitude swelling of the mitochondria and swollen endoplasmic reticulum also were observed in a few cells. The alterations that appeared after a 200 V/cm shock included contracture and disorganization of the myofibrils, large-amplitude swelling and loss of cristae in the mitochondria, swollen endoplasmic reticulum and nuclear envelope, and intracellular edema. The degree of ultrastructural change was dependent on the intensity of the shock. These structural alterations are consistent with an osmotic imbalance which occurs during a shock-induced prolonged depolarization of the cell membrane (Jones et al., 1978a), possibly due to a transient dielectric breakdown during the shock, and may underlie the arrhythmias and necrosis which often occur after high-intensity clinical and experimental eountershock procedures in vivo.

Histologic changes and arrhythmogenicity after discharge through transseptal catheter electrode.

“…Unlike ischemic infarction, myocardial injury was detected within 30 min of the application of electroshock, well before any inflammatory reaction. Electron micrographic findings of contraction bands, increased mitochondrial numbers, and electron-dense mitochondrial inclusions are common in descriptions of ischemic22' 23 and electrical myocardial injury,24 25 suggesting these may be nonspecific myocardial responses to severe injury. The intense local inflammatory reaction evolved to organization and replacement by scar in every dog examined.…”

Cardiovascular responses to transvenous electrical cardioversion of atrial fibrillation in anaesthetized horses

“…Although several of these can, at least partly, be attributed to the preceding ventricular fibrillation, electroshocks per se may also depress ventricular function. In vitro , injury to the cardiac sarcolemmal membrane (so called electroporation) after defibrillation shocks (Jones et al. 1980) or high‐intensity electric field stimulation (Jones et al.…”

“…1980) or high‐intensity electric field stimulation (Jones et al. 1987) has been reported and may result in short‐lived myocardial functional deficits, although recovery probably occurs within seconds (Jones et al. 1980, 1987).…”

Prevention of Sudden Death – Implantable Cardioverter Defibrillator and/or Ventricular Radiofrequency Ablation

“…The first explanation is a www.intechopen.com Cardiac Defibrillation -Prediction, Prevention and Management of Cardiovascular Arrhythmic Events 86 direct damage on the myocardium. Animal models have demonstrated a vast array of potentially deleterious effects of DC shocks including alterations in cellular morphology, biochemical function, electrophysiologic function, and hemodynamic function (Tedeschi, 1954;Van Vleet, 1977;Babbs, 1980;Jones, 1980;Wilson, 1988;Trouton, 1992). Many of the morphologic, biochemical, electrophysiologic and hemodynamic adverse effects of high-intensity DC shocks reported in animals models have also been noted, although with lower frequency, in patients who have received DC shocks of clinically significant intensities.…”