Abstract
Abstract Introduction Cardiovascular diseases represent a major cause of death world-wide and one of their greatest complications is the development of cardiac arrhythmias, in which ventricular fibrillation (VF) stands out as the most severe one. The only therapy that reverses VF is defibrillation. However defibrillatory shock is capable of killing heart cells and it is known that the orientation of the cell major axis with respect to the electrical field (E) direction is a determining factor for cellular excitation and injury, which is leading to the development of new defibrillation protocols. The aim of this work is to fill the gap in information about cell lethality for intermediate cell orientation angles. Methods Ventricular myocytes were extracted from adult male Wistar rats and the cells were plated in a chamber for perfusion and stimulation with bipolar voltage pulses to determine the stimulation threshold (ET). Then, monopolar stimulus was applied and amplitude was increased until cell lethal injury. This protocol was performed on four experimental groups: cells oriented at 0°, 30°, 60° and 90°, with respect to E direction. Results 87 cells were analyzed and an increase in amplitude of E associated with 50% lethality (E50) was verified as the direction of E application and cell major axis orientation departed. Conclusion Taken the same probability of lethality, our data suggest a nonlinear increase of E amplitude from 0° to 90° similar to that of ET. These in-between data had not yet been shown and are important for service-based future defibrillation protocols.
Highlights
Cardiovascular diseases represent a major cause of death world-wide and one of their greatest complications is the development of cardiac arrhythmias, in which ventricular fibrillation (VF) stands out as the most severe one
Values found for ∆VT, cell length and cell width were similar to those previously found in the literature (Bassani et al, 2006; Goulart et al, 2012; Oliveira et al, 2008)
It was not verified statistical difference among the experimental groups, which is important to ensure homogeneity of the cell samples used since it has already been shown that different cell sizes may influence excitation threshold (ET) and lethal E (Goulart et al, 2012)
Summary
Cardiovascular diseases represent a major cause of death world-wide and one of their greatest complications is the development of cardiac arrhythmias, in which ventricular fibrillation (VF) stands out as the most severe one. One of the major complications resulting from cardiovascular diseases is the development of cardiac arrhythmias, in which ventricular fibrillation (VF) stands out as the most severe and life-threatening arrhythmia, being able to quickly lead to the development of cardiac arrest and even death.
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