What is the approximate current level known to cause ventricular fibrillation in adult humans with epicardial contact?

The approximate current level known to cause ventricular fibrillation in adult humans with epicardial contact is around 50 microamperes (uA). Ventricular fibrillation is a critical condition where the heart's electrical rhythm becomes disorganized, leading to ineffective pumping and potential cardiac arrest. Research has shown that this threshold of approximately 50 uA is sufficient to disrupt the heart’s normal electromechanical function when direct contact with the heart tissue occurs.

Understanding this level is crucial for medical professionals, especially when working with devices that may deliver electrical shocks, such as defibrillators. The implementation and calibration of such devices rely on knowledge of these thresholds to ensure patient safety while providing effective treatment. Higher currents can lead to more severe cardiac disturbances or damage to heart tissue, while lower currents may not elicit significant physiological responses.