What is the role of Willem Einthoven in the field of electrocardiography? He was the first to measure blood pressure He invented the ECG machine He discovered the SA node He developed the standard limb lead

The correct answer is **He invented the ECG machine**. Here's why:* **Willem Einthoven** is considered the **father of electrocardiography**. He was a Dutch physiologist who, in 1903, invented the **string galvanometer**, a device that allowed for the recording of electrical activity in the heart. This invention paved the way for the development of the modern electrocardiogram (ECG) machine.Let's look at the other options:* **He was the first to measure blood pressure:** While blood pressure measurement is crucial in medicine, this was not Einthoven's primary contribution. * **He discovered the SA node:** The sinoatrial (SA) node, the heart's natural pacemaker, was discovered by others, not Einthoven.* **He developed the standard limb lead:** Einthoven did develop the standard limb lead system, which is still used today, but his primary contribution was the invention of the ECG machine itself. **In summary, Willem Einthoven's invention of the string galvanometer revolutionized the field of cardiology by allowing for the non-invasive recording of electrical activity in the heart, leading to the development of the ECG machine.**