Your health tracker may not always be perfect—but for 28-year-old James Green of Brooklyn, New York, receiving a simple alert from his Apple Watch saved his life.
Green tweeted on Friday that HeartWatch, one of the Apple Watch’s health sensors, measured his heart rate at consistently above his resting rate of 54, even though he was just sitting at his desk. Turns out those spikes were signaling a pulmonary embolism, his doctors told him after he made his way to the hospital, where they performed CT scans to reach their diagnosis, The Telegraph reports.
A pulmonary embolism occurs when a clot deep in your vein, most commonly in your leg, travels to your lungs from its original spot, blocking some or even all of your blood supply, according to the American Heart Association. This can prevent vital organs from getting the oxygen and blood they need to properly function, which can be fatal.
Green, a self-proclaimed “serial health tracker,” has experienced a pulmonary embolism before, meaning he had all the more reason to pay attention to what his heart is doing. While he suffers from generalised anxiety disorder, he told The Telegraph he was experiencing other symptoms during the time he received the heart rate alert, which pushed him to believe that he wasn’t experiencing a panic attack, but rather “something more.”
HeartWatch monitors your heart rate data across four views: Waking, Regular, Workout, and Sleeping. Each view is isolated so you can learn to notice unusual changes in how your heart is beating, according to the app’s official page.
After Green’s diagnosis, his doctors performed a couple of ultrasounds and prescribed him blood thinners, which interfere with the proteins in your body responsible for blood clots, working to minimize the damage.
If you're looking to avoid any blood complications, check out the best 5 foods for your heart.
This article originally appeared on Men's Health