Lethal effect of electric fields on isolated ventricular myocytes

Area of Science:

• Cardiovascular Science
• Electrophysiology
• Cellular Biology

Background:

• Defibrillator shocks can induce electrical and contractile dysfunction in cardiomyocytes.
• Understanding the cellular response to defibrillator shocks is crucial for optimizing defibrillation strategies.

Purpose of the Study:

• To investigate the relationship between electric field intensity and lethal injury probability in isolated rat ventricular myocytes.
• To analyze the influence of electric field orientation and stimulus waveform on myocyte injury.

Main Methods:

• Isolated rat ventricular myocytes were subjected to controlled electric field stimuli.
• Variations in transmembrane potential and cell death were measured under different electric field intensities, orientations, and waveforms.

Main Results:

• A sigmoidal relationship was observed between electric field intensity and lethal injury, with irreversible injury occurring above 50 V/cm.
• Myocytes were twofold more sensitive to electric fields applied longitudinally versus transversally to the cell axis.
• Biphasic shocks caused less cell injury than monophasic shocks for the same stimulus duration and electric field intensity.

Conclusions:

• While defibrillator shocks can cause significant myocyte death within clinically relevant electric field ranges, biphasic waveforms demonstrate a reduced likelihood of irreversible cell injury.
• Field orientation and stimulus waveform are critical factors influencing myocyte sensitivity and injury during defibrillation.