What does the "PP interval" on an EKG measure?

The "PP interval" on an EKG specifically measures the time between consecutive P waves. This interval is particularly important for assessing the atrial rhythm and can help identify arrhythmias, such as atrial flutter or atrial fibrillation, where the P waves may become irregular. By measuring the PP interval, healthcare providers can determine the frequency of atrial contractions and evaluate the overall cardiac rhythm more accurately.

Understanding the other choices adds clarity. The time between systole and diastole, for instance, relates to the cardiac cycle rather than the electrical activity represented by P waves. The overall heart rate is derived from the measurement of intervals like the RR interval or counting beats over time, but it does not specifically reflect the interval between P waves. Finally, the duration of the PR interval is separate from the PP interval; the PR interval encompasses the time from the beginning of the P wave to the beginning of the QRS complex, indicating the time taken for electrical impulses to travel through the AV node, not just the atrial activity represented by the P waves.