What is the primary purpose of an electrocardiogram?

The primary purpose of an electrocardiogram (ECG or EKG) is to assess the electrical activity of the heart. This diagnostic tool records the electrical impulses that trigger heartbeats, providing crucial information about the heart's rhythm, rate, and overall electrical conduction system. By analyzing the waves displayed on an ECG, healthcare providers can identify various heart conditions, such as arrhythmias, ischemia, and previous heart attacks.

Other options focus on different aspects of cardiovascular health. Measuring blood flow rate pertains more to techniques like Doppler ultrasound, which evaluates blood circulation, rather than the electrical activity, which is what an electrocardiogram specifically measures. Evaluating heart muscle strength typically involves imaging techniques, such as echocardiography, which can assess the structural function of the heart but does not provide direct electrical activity assessments. Lastly, determining oxygen levels in the blood is usually done through arterial blood gas tests or pulse oximetry, rather than through an ECG, which does not measure gas exchange directly. Therefore, the correct answer emphasizes the core function of the electrocardiogram in monitoring and diagnosing electrical heart activity.