Which statement about ECG (or EKG) devices is true?

• A. Detects maximum oxygen uptake
• B. Detects heart murmurs
• C. Measures heart chamber size
• D. Detects arrhythmias

Answer: (D)

An ECG is a tool that monitors the heart’s electrical activity over time, which is key for identifying rhythm problems. The track it provides shows the timing and pattern of electrical signals that coordinate heartbeats. When a rhythm is off—such as irregular spacing between beats, an unusual pace, or abnormal conduction—the ECG reveals these arrhythmias through characteristic patterns like irregular P–R intervals, wide or absent QRS complexes, or irregular ventricular responses. That makes it the most direct and reliable method for detecting arrhythmias.

Maximum oxygen uptake, or VO2 max, is measured with metabolic testing during exercise and gas analysis, not with an ECG. Heart murmurs are sounds produced by turbulent blood flow through the valves and are detected with a stethoscope during auscultation, not by measuring electrical activity. Heart chamber size is assessed with imaging techniques such as echocardiography or MRI, which visualize structures rather than electrical signals. So the ECG’s primary strength is revealing arrhythmias, not these other aspects.