What is the test that checks the heart's electrical activity and presents line tracings on paper with waves?

• A. ECG
• B. Echocardiogram
• C. MRI
• D. CT scan

Answer: (A)

An electrocardiogram records the heart’s electrical activity and presents line tracings on paper or a screen. Those tracings show the familiar waves: the P wave reflects atrial depolarization, the QRS complex reflects ventricular depolarization, and the T wave reflects ventricular repolarization. By analyzing the size, timing, and rhythm of these waves, clinicians assess heart rate, rhythm disturbances, and conduction problems, and can detect signs of ischemia or past infarction. It’s a quick, noninvasive test that directly measures electrical activity.

Other imaging options serve different purposes: an echocardiogram uses ultrasound to visualize heart structure and function (chambers, valves, motion), MRI provides detailed tissue and anatomy images, and CT scans give cross-sectional anatomy and, with contrast, detail of blood vessels.