Figure 1.

Example of measuring multi-lead electrocardiogram (ECG) from a smartwatch. Multiple-lead ECG can be obtained from smartwatches by sequentially placing the smartwatch on different parts of the body. The figure depicts an example of measuring leads I, II, V1, and V4 sequentially. Lead I can be recorded with the smartwatch on the left wrist and the right index finger on the crown. Then, after removing the smartwatch from the left wrist, lead II can be recorded with the smartwatch on the left lower quadrant of the abdomen and the right index finger on the crown. Next, leads V1 and V4 can be recorded with the smartwatch on the fourth intercostal space at the right sternal border and fifth intercostal space at the midclavicular line, respectively, with the right index finger on the crown in both cases.