One of the most anticipated features on the all-new Apple Watch Series 4 is the introduction of an electrical heart rate sensor that can take an electrocardiogram (ECG) using a new ECG app. Soon after announcing the new watch, Apple released more information on this ground-breaking technology. 

The new technology, which has been granted a De Novo classification by the FDA, takes advantage of the electrodes built into the wearable device’s Digital Crown and new electrical heart rate sensor in the back crystal. From the ECG app, you need to touch the Digital Crown for 30 seconds. From there, you’ll receive a heart rhythm classification. This information will tell you whether it detected a normal pattern or whether there are signs of Atrial Fibrillation or AFib, which is a heart condition that could lead to significant problems.

Data collected through the ECG app is automatically sent to the Apple Health app. You can share this information with your doctor by sending a PDF.

With watchOS 5, Apple Watch also intermittently analyzes heart rhythms and sends a notification when it detects an irregular heart rhythm. It will also alert you if your heart rate exceeds or falls below a specified threshold.

The new ECG technology will be released later this year through a software update for the Apple Watch Series 4. It’s only available for users in the United States.

The Apple Watch Series 4 is available in two versions, 40m and 44mm. On each, the display is over 30 percent larger than on previous models. The wearable device includes new watch faces and can detect if you have a fall, Pre-orders for the Apple Watch Series 4 are being accepted in many countries beginning on Friday, Sept. 14 with prices beginning at $399 for the GPS model and $499 for the GPS + Cellular model.