In the evaluation of hypocalcemia, what heart rhythm change is often observed?

In the context of hypocalcemia, a common cardiac manifestation is the prolongation of the QT interval on an electrocardiogram (ECG). This prolongation occurs due to the influence of low calcium levels on the electrical activity of the heart. Calcium plays a critical role in cardiac myocyte action potential generation and propagation. Specifically, calcium ions are essential for the depolarization and repolarization phases of the cardiac cycle.

When calcium levels drop, one of the key effects is the prolongation of the ventricular action potential duration, which can be visualized as a longer QT interval on the ECG. This alteration increases the risk of potentially life-threatening arrhythmias, such as Torsades de Pointes, which is a specific type of polymorphic ventricular tachycardia.

On the other hand, options like bradycardia and atrial fibrillation are not directly associated with hypocalcemia; rather, they are influenced by other electrolyte disturbances or cardiac conditions. Ventricular tachycardia is also not specifically linked to hypocalcemia in the same way that a prolonged QT interval is. Therefore, the characteristic ECG change seen in hypocalcemia is the prolongation of the QT interval, making it the correct answer in the evaluation