Did Einthoven invent the first ECG machine?
A common misconception is that I invented the very first device to record the heart's electricity. In fact, Augustus Waller had already demonstrated the human electrocardiogram in 1887 using a capillary electrometer, but his recordings were crude and unreliable—the instrument's response was too slow to capture the heart's rapid electrical events. My contribution was not the concept of recording cardiac electricity, but the development of a practical, sensitive instrument that could produce accurate, reproducible tracings. The string galvanometer, which I perfected between 1901 and 1903, had a response time of less than 0.01 seconds, allowing it to faithfully reproduce the P, QRS, and T waves of the ECG. I also introduced the standard limb leads and the mathematical framework for interpreting them. So while Waller deserves credit for the first demonstration, I provided the tools and theory that made the ECG a clinical reality.
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