At what current value do heart rhythm problems begin?

At what current value do heart rhythm problems begin?

• A. 75 mA
• B. 5 mA
• C. 10 mA
• D. 100 mA

Answer: (A)

The tendency for the heart to go into dangerous rhythm disturbances happens when enough current can pass through the chest to disrupt the heart’s electrical signaling. At power‑line frequencies (AC around 60 Hz), there is a threshold in the tens of milliamps where ventricular fibrillation becomes possible. About 75 milliamps is a commonly cited value for the current level at which heart rhythm problems can begin under typical conditions (wet skin, path through the chest). Currents well below that are more likely to cause tingling or a weak grip and are less likely to trigger fibrillation, while currents around and above this level markedly raise the risk of dangerous heart rhythms. The exact threshold can vary with skin resistance, contact area, duration, and the path the current takes through the body, but 75 mA captures the practical point where the heart’s rhythm starts to be seriously affected. For safety, any substantial current through the body from a shock is a serious hazard and should be treated with extreme caution.

The tendency for the heart to go into dangerous rhythm disturbances happens when enough current can pass through the chest to disrupt the heart’s electrical signaling. At power‑line frequencies (AC around 60 Hz), there is a threshold in the tens of milliamps where ventricular fibrillation becomes possible. About 75 milliamps is a commonly cited value for the current level at which heart rhythm problems can begin under typical conditions (wet skin, path through the chest). Currents well below that are more likely to cause tingling or a weak grip and are less likely to trigger fibrillation, while currents around and above this level markedly raise the risk of dangerous heart rhythms. The exact threshold can vary with skin resistance, contact area, duration, and the path the current takes through the body, but 75 mA captures the practical point where the heart’s rhythm starts to be seriously affected. For safety, any substantial current through the body from a shock is a serious hazard and should be treated with extreme caution.