Picture a typical doctor's trip, where a blood pressure cuff is wrapped around your bicep and inflated to get a reading. HeartGuide works similarly: A thin airbag sits under the watch band, tightening gradually around your wrist to read your blood pressure at the press of button. The process takes 30-40 seconds and requires you to raise your arm to your heart. "It's the exact same technique we've used for 40 years, we've just made it wearable," said Jeff Ray, Omron Healthcare's executive director of new technology.

The benefits, Ray says, are that anyone dealing with heart attack and stroke risks can monitor how their daily activity -- exercise, diet, medication -- affects their systolic and diastolic pressure, which changes over the course of the day. While it still requires the user to be diligent about regular measurements and correlate it with their behavior, Ray says they may allow the watch to make automatic measurements in future.

All data is stored in HIPAA-compliant databases, and you have to opt in to share it with doctors or other apps. Besides blood pressure, HeartGuide also monitors activity like steps, calories and sleep, requiring charging two to three times per week (or every 40 blood pressure measurements). It ships on January 8 for $499.