CAMRT Radiography Practice Exam

Which wave on an ECG corresponds to cardiac diastole?

1. T wave

2. P wave

3. QRS complex

4. U wave

The correct answer is: T wave

The T wave on an ECG corresponds to the phase of cardiac diastole. During diastole, the heart's ventricles are relaxed and filled with blood, following the contraction of the heart during systole. The T wave specifically represents the repolarization of the ventricles, which occurs just before they enter diastole. This repolarization signifies that the ventricles are resetting their electrical state in preparation for the next heartbeat. In contrast, the P wave represents atrial depolarization, which occurs prior to the contraction of the atria. The QRS complex captures the depolarization of the ventricles, marking the beginning of ventricular contraction (systole). The U wave, while not as well understood, is believed to represent repolarization of the Purkinje fibers or the late repolarization of the ventricles but is not directly associated with the diastolic phase. Understanding the phases of the cardiac cycle and their corresponding ECG components is vital for interpreting the heart's electrical activity and function.