ECG Vs PPG: Key Distinctions In Heart Activity Monitoring

ECG and PPG represent separate approaches used to measure heart activity, but they function through unique mechanisms and provide complementary information. The term ECG refers to electrocardiogram and detects cardiac electrical impulses produced by the heart as it beats. The detection relies on skin-mounted electrodes, typically on the chest, arms, or legs. The recorded trace shows the pattern and intensity of the electrochemical triggers that trigger cardiac contractions. This makes ECG highly accurate for identifying arrhythmias, heart attacks, and other electrical abnormalities in the heart.



The acronym PPG refers to photoplethysmogram and relies on optical sensing to track variations in vascular blood flow in the vessels. The PPG device, commonly found in fitness trackers and smartwatches, projects wavelengths such as green or IR into the skin and analyzes the intensity of returned light. As blood flows through the vessels with each heartbeat, the optical density changes slightly, permitting pulse rate approximation and occasionally reveal flow irregularities. PPG is ideal for ongoing, contactless assessment during everyday routines, but it is easily disrupted by motion, pigmentation levels, and ambient lighting, which can affect its accuracy.



While ECG gives a detailed view of the heart’s bioelectric patterns, PPG is indicative of the mechanical side of the heartbeat—the arterial pressure wave generated by ventricular contraction through arteries. ECG is the gold standard in healthcare facilities for diagnosing cardiac conditions, whereas PPG serves primarily for non-clinical fitness tracker assessment and heart rate estimation. Newer health gadgets merge ECG and PPG to provide deeper physiological understanding, but it’s important to understand that they are not interchangeable. ECG is superior for targeted cardiac diagnosis, while PPG supports continuous wellness observation in real-world settings.