--- description: The Kardia band for Apple Watch detects electrical activity produced by the heart to learn about your health. title: This New Apple Accessory Can Predict a Stroke image: https://static.time.com/v3/assets/bltea6093859af6183b/bltbdd39dcb7b70c0ea/69888b3a2dce01a5739e838a/kardia.jpg?branch=production&width=828&quality=75&auto=webp&crop=16:9 ---  * [Business](/section/business/) ## Business Update your preferences in [Account Settings](/account/preferences/) Close * [Tech](/tag/time-section-tech/) ## Tech Update your preferences in [Account Settings](/account/preferences/) Close # This New Apple Watch Accessory Can Predict a Leading Cause of Strokes  by [Lisa Eadicicco](/author/lisa-eadicicco/)  ## Lisa Eadicicco Update your preferences in [Account Settings](/account/preferences/) Close Updated: Dec 13, 2023 4:12 PM CUTPublished: Mar 16, 2016 2:25 PM CUT  Kardia Band for Apple Watch (PRNewsFoto/AliveCor, Inc.) Kardia Band for Apple Watch (PRNewsFoto/AliveCor, Inc.)AliveCor Inc. via PR NEWSWIRE—PR NEWSWIRE  by [Lisa Eadicicco](/author/lisa-eadicicco/)  ## Lisa Eadicicco Update your preferences in [Account Settings](/account/preferences/) Close Updated: Dec 13, 2023 4:12 PM CUTPublished: Mar 16, 2016 2:25 PM CUT The Apple Watch already comes with a built-in heart rate monitor, but certain factors can prevent it from getting an accurate reading. The way the strap fits on a user’s wrist, how he or she moves their wrist, and the presence of tattoos can all impact the device’s heart rate monitor, [as Apple explains](https://support.apple.com/en-us/HT204666 "undefined"). But [AliveCor’s Kardia Band ](http://www.prnewswire.com/news-releases/new-kardia-band-for-apple-watch-delivers-medical-grade-electrocardiogram-ekg-anytime-anywhere-300236825.html "undefined")claims to bring medical-grade heart tracking to the Apple Watch by using a different type of technology more commonly used by health professionals. The Kardia band for Apple Watch, which is expected to be available in late spring, uses electrocardiogram technology (EKG) to check the state of a wearer’s heart. The Apple Watch’s heart rate sensor works through photoplethysmography, which flashes LED lights hundreds of times per second to detect blood flow through the wrist. This allows the watch to calculate how many times a wearer’s heart beats per minute. EKG sensors instead monitor the electrical signals that are produced by a heartbeat, [according](http://www.heart.org/HEARTORG/Conditions/HeartAttack/SymptomsDiagnosisofHeartAttack/Electrocardiogram-ECG-or-EKG%5FUCM%5F309050%5FArticle.jsp#.VulmLVPG29U "undefined") to The American Heart Association. ### See What's Inside the Apple Watch  The display is carefully removed, revealing the innards of the Apple Watch iFixit  A plastic tool is used to remove the device’s battery. The Apple Watch sports a 3.8 V, 0.78 Wh lithium-ion battery, which has a life of about 18 hours for general use before needing a recharge iFixit  The Taptic Engine is the tiny motor that provides force feedback whenever the watchface is pressed or when the user receives a notification. Here, we see that it is attached to the Apple Watch’s speaker iFixit  The antenna assembly is removed, which likely controls the watch’s Wi-Fi and Bluetooth functionality iFixit  Removing the digital crown bracket is the final step before having access to the Apple Watch’s integrated computer chip, the S1 iFixit  Deep in the Apple Watch’s casing is the S1, the integrated computer chip that gives the device its smarts. It’s extremely difficult to remove iFixit  At the bottom of the watch case lies the plethysmograph that serves as the Apple Watch’s heart rate monitor. The device may also be able to measure a user’s blood oxygen level, but Apple hasn’t promoted this feature, possibly due to FDA regulations iFixit  The separate components of the Apple Watch iFixit AliveCor says the sensor in its band for the Apple Watch can detect Atrial fibrillation, which is an irregular heart rate that can increase the risk of a stroke and other heart complications, as The Mayo Clinic [explains](http://www.mayoclinic.org/diseases-conditions/atrial-fibrillation/home/ovc-20164923 "undefined"). The strap is also capable of detecting whether or not a user’s heart rate and heart rhythm are normal, and can alert wearers when a reading is unreliable so that another can be taken. Kardia works with an accompanying app made by AliveCor and feeds data into Apple’s Health app, allowing users to track their EKG readings along with the other types of health information the Apple Watch records, like step and calorie count. 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