Mild hyperkalemia can affect muscle tissues, causing mild muscle tremors, while severe hyperkalemia may reduce the excitability of neuromuscular functions, leading to weakness and even flaccid paralysis in the limbs. Hyperkalemia can also impact the heart, mainly resulting in decreased myocardial excitability, decreased myocardial conductivity, and decreased myocardial automaticity. The effects on the electrocardiogram (ECG) primarily manifest as low and widened P waves, widened QS complexes, decreased R waves, and elevated T waves. Regarding myocardial contractility, hyperkalemia mainly causes a decrease in contractility and can lead to metabolic acidosis.