Credit: AppleApple has introduced hypertension (chronic high blood pressure) notifications to compatible Apple Watch models in more than 150 countries and regions. According to Apple, those who own an Apple Watch Series 9 or later or an Apple Watch Ultra 2 or later can update their devices to the latest version of watchOS to begin using the feature. The feature reportedly uses the wearable's optical heart sensor to analyze how a person's blood vessels respond to heartbeats over a 30-day period. The Apple Watch uses new machine learning techniques to check your health data. If it finds signs that you may have high blood pressure, it will present a notification.