Patient Care Technician (PCT) AAH Practice Exam

Which condition may present with a prolonged QT interval?

1. Hyperkalemia

2. Hypocalcemia

3. Sick sinus syndrome

4. Atrial fibrillation

The correct answer is: Hypocalcemia

A prolonged QT interval is an important finding on an electrocardiogram (ECG) that can indicate an increased risk of serious arrhythmias. Hypocalcemia, which is a low level of calcium in the blood, can lead to this prolonged QT interval due to the vital role calcium plays in cardiac muscle contraction and electrical conduction in the heart. When calcium levels drop, it affects the heart's repolarization phase, which can manifest as a lengthened QT interval. Monitoring and evaluating patients for changes in the QT interval is crucial, especially in those with electrolyte imbalances like hypocalcemia. Other conditions, while they may impact cardiac function or rhythm, do not specifically relate to the prolongation of the QT interval in the same way. For example, hyperkalemia can affect the heart but is more associated with changes in the QRS complex rather than a prolonged QT. Sick sinus syndrome is primarily a problem with the heartbeat's natural pacemaker, and atrial fibrillation is an irregular rhythm that does not specifically correlate with a prolonged QT interval. Thus, understanding the pathophysiology of hypocalcemia clarifies its direct impact on the QT interval.