Patient Care Technician (PCT) AAH Practice Exam

U waves are thought to represent the repolarization of which heart structure?

1. AV node

2. Purkinje fibers

3. Myocardium

4. Atria

The correct answer is: Purkinje fibers

The U waves seen on an electrocardiogram (ECG) are generally believed to reflect the repolarization of the Purkinje fibers. These specialized fibers are responsible for conducting electrical impulses throughout the ventricles, leading to coordinated contraction. U waves often appear after the T wave, which represents the repolarization of the ventricles, indicating a potential electrical activity associated with the Purkinje fibers as they reset for the next cycle. Understanding the context of U waves is essential, as they can be influenced by various factors, including electrolyte imbalances and heart rate. While other heart structures like the AV node, myocardium, and atria have their own unique roles in electrical conduction and repolarization, it is the Purkinje fibers that are most closely associated with U waves on an ECG. This makes Purkinje fibers the correct choice for representing the repolarization indicated by U waves.