Quanttus's original research device. The current prototype is worn on the wrist.

Quanttus, the stealthy Cambridge, Massachusetts-based startup that raised $19 million last year for a wearable vitals monitor is deep into clinical tests for its wristworn device, which is tackling the intractable problem of continuous blood pressure monitoring.

"Cardiovascular disease is the number one killer in the US, and it hits more than all cancers and AIDS combined," David He, cofounder and chief scientific officer of Quanttus, said at the HxRefactored event last week. "But if you look at the apparatus used in the last hundred years, versus what you see in the doctors’ office today, it hasn’t changed much. Actually if it weren’t for the ban on the use of mercury, you’d still see the same devices. There has been some innovation: Withings has done some work to make the experience better. But it’s still the same technology. It’s uncomfortable, episodic, and burdensome."

Most blood pressure monitors still rely on a cuff that slows the flow of blood, which is both uncomfortable and makes continuous monitoring impossible. It also makes nocturnal monitoring difficult-to-impossible, which is one of the biggest value propositions for Quanttus. According to He, studies have shown that when patients' blood pressure doesn't drop at night, patients are more at risk for heart disease.

"Every 5 percent decrease in your drop in blood pressure at night reduces your risk of cardiovascular disease by 20 percent," he said. "This is huge. It’s way more diagnostic than getting your blood pressure taken at a doctor’s office or at home."

The startup has already done a number of tests on its device at Massachusetts General Hospital, and is planning to scale those up as they seek to gather enough data for an FDA clearance. He said they hope to have the device on "thousands of wrists" for testing purposes in the near future.

By offering a clinical but consumer-friendly wearable device, Quanttus hopes to identify other predictive trends, like nocturnal blood pressure, that haven't been visible before because continuous blood pressure monitoring is so uncommon at present.

They also want the tool to help users self-manage their blood pressure. The initial design of the device was placed behind the user's ear. But, according to VP of Experience Design Scott Mackie, who also spoke at the event, they moved it to the wrist so users could interact with the device like a watch, to promote not just monitoring but behavior change.

"Less than 50 percent of people with hypertension have it under control," Mackie said. "They’re just letting it slowly kill them. And the big reason for that is it’s subtle. You don’t feel it. You don’t know how to affect it. There’s no feedback loop. If we can monitor your blood pressure and explore the causes, we can start to build that feedback loop between what I choose to do and how healthy I am, and our hope is that that can be an accelerated feedback loop. ... It’s only through sustained continuous engagement that people are going to reach the outcome that they really want."

The company will focus on five generally accepted measures for controlling blood pressure: educating people about their numbers, improving their medication habits, moderating their diet (including sodium, caffeine, alcohol, and tobacco), encouraging physical activity, and managing stress levels. The company is in the process of developing algorithms that monitor these factors and can provide nudges to ultimately change users' behavior.