Evolution of the clinical electrocardiogram.

As a laboratory procedure the electrocardiogram (ECG) is unique, having been in continuous and ever increasing use since its introduction nearly 90 years ago by Willem Einthoven. Some would suggest that, conservatively speaking, a volume of approximately 100 million ECGs recorded annually at a cost approaching $5 billion attests to the importance of the procedure. Others would point to the capability and versatility of the ECG as far more important measures of its contribution to the care of patients with and without heart disease. Electrocardiography, the only practical method of recording the electrical behavior of the heart, has the potential to reflect anatomy, blood flow, served that if the nerve of the Galvani nerve-muscle preparation was laid across the beating heart, the muscle of the nerve-muscle preparation contracted in synchrony with the beating heart. In 1855, Kolliker and Muller also placed the