A measurement of heart electrical activity.

• A. Electroencephalogram
• B. Echocardiogram
• C. Angiogram
• D. Electrocardiogram (EKG)

Answer: (D)

Measuring the heart's electrical activity is what an electrocardiogram does. The heart generates electrical impulses that coordinate its beating, and an electrocardiogram records these impulses with skin electrodes to produce a tracing of atrial and ventricular depolarization and repolarization over time. This tracing helps assess heart rhythm, conduction problems, and potential ischemia or injury. The other tests look at different things: an electroencephalogram measures brain electrical activity; an echocardiogram uses ultrasound to visualize heart structure and motion; an angiogram uses contrast and X-rays to image blood vessels. Since the item asks for a test that records electrical signals from the heart, the electrocardiogram is the appropriate choice.