What does a 12-lead ECG refer to?

• A. A single-lead monitor.
• B. An ECG in which 12 nodes are used to measure the electrical activity of the heart.
• C. An EEG.
• D. An ultrasound of the heart.

Answer: (B)

A 12-lead ECG records the heart’s electrical activity from many angles using multiple electrodes. It uses ten physical electrodes placed on the limbs and chest to derive twelve different leads, giving views of the heart in both the frontal and horizontal planes. This multi-view setup lets clinicians see how electrical activity travels through different regions of the heart, helping to identify problems such as ischemia or infarction and to analyze rhythm and conduction. It’s distinct from an EEG, which measures brain activity, and from an ultrasound (echo), which images the heart’s structure and motion using sound waves.