Final answer:
Hypercalcemia can affect heart rate and contractility. It may lead to a shortened QT interval in the ECG.
Step-by-step explanation:
Hypercalcemia is a condition characterized by high levels of calcium ions in the blood. When calcium ion levels increase, heart rate (HR) and contractility also increase. In an electrocardiogram (ECG), hypercalcemia may be associated with a short QT interval and a widened T wave. On the other hand, hypocalcemia (low levels of calcium ions) may result in a prolonged QT interval.