What effect does hypercalcemia have on the heart?

Hypercalcemia, which refers to elevated levels of calcium in the blood, significantly influences cardiac function, primarily by affecting the excitability and contractility of cardiac muscle. One of the key effects of hypercalcemia is increased heart irritability, which can lead to arrhythmias. High calcium levels enhance the rhythmicity of cardiac cells, making them more prone to depolarization and thus increasing the likelihood of abnormal heart rhythms.

When calcium levels are elevated, the action potential duration in cardiac myocytes is lengthened, promoting greater spontaneous activity and excitability. This heightened irritability can result in various arrhythmias, as the heart becomes more susceptible to abnormal electrical activity.

In the context of other choices, decreased heart rate typically results from increased parasympathetic activity or decreased sympathetic drive, neither of which is directly linked to hypercalcemia. Weakened contractions are not characteristic of hypercalcemia; in fact, increased calcium levels generally enhance the strength of cardiac contractions. As for stimulated blood flow, this is more influenced by factors such as vascular resistance and heart rate rather than directly by calcium levels in the blood. Therefore, the option stating that hypercalcemia increases heart irritability aligns with the physiological responses observed under conditions of elevated calcium in the