A 65-year-old man had an ECG at a local emergency after a biking accident. His weight was 80 kg, and his blood pressure was 160/90 mm Hg. The QRS voltage was 0.5 millivolt in lead I and 1.5 millivolts in lead III. What is the QRS voltage in lead II?
High-Yield Explanation
Einthoven's law states that the voltage in lead I plus the voltage in lead III is equal to the voltage in lead II, i.e. II = I + III which in this case is 2.0 millivolts