Which electrolyte imbalance can cause an atrioventricular block?

Hyperkalemia

Hyperkalemia is a condition in which there is too much potassium in the blood. It can cause an atrioventricular block because potassium can slow down the conduction of electrical impulses in the heart. This can lead to a delay in the electrical signals that cause the heart to contract, which can result in an atrioventricular block.