Which diagnostic test records the electrical activity of the heart?

• A. EEG
• B. Electrolyte panel
• C. ECG
• D. EMG

Answer: (C)

Understanding which test records the heart's electrical activity. The heart beats due to electrical impulses that travel through the heart muscle, and these signals can be captured noninvasively with electrodes on the skin. An electrocardiogram uses these electrodes to trace the heart’s electrical activity over time, producing a waveform that shows heart rate, rhythm, and conduction patterns. This makes it the primary tool for detecting arrhythmias, blocks, and signs of ischemia or infarction.

EEG records electrical activity of the brain, EMG records electrical activity of muscles, and an electrolyte panel screens blood electrolyte levels rather than heart signals.

So, the test that records the electrical activity of the heart is the electrocardiogram.