What aspect of heart function does an ECG NOT typically indicate?

An electrocardiogram (ECG or EKG) primarily measures the electrical activity of the heart, showcasing information about heart rhythm, heart rate, and potential abnormalities in electrical conduction. It reflects the timing and strength of electrical signals that prompt heart contractions. Therefore, it can effectively indicate heart rhythm abnormalities, which involve irregularities in the timing of heartbeats, and it can display heart rate variations based on the frequency of these signals.

However, an ECG does not provide direct measurement of blood pressure readings. Blood pressure is determined by the force of blood against the walls of arteries and requires different equipment, such as a sphygmomanometer, to assess. The ECG does not reflect this mechanical aspect of cardiovascular function; it focuses strictly on the electrical activity related to the heart's contractions. Thus, the correct answer identifies that blood pressure readings are not indicated by an ECG.