Willem Einthoven (1860 – 1927) was a Dutch physician and physiologist. Invented the first practical electrocardiogram (ECG) in 1903
A brief history of the ECG and electrocardiography and the eponymous names behind the ECG/EKG...
ECG features of Upper Limb Lead reversal - left arm/right arm lead reversal. Einthoven's triangle flips 180 degrees horizontally around an axis formed by lead aVF.
A review of the different types of limb lead reversal with some excellent example ECGs and Einthoven's triangle explanation