By Sree Roy
Sleep specialists can increase their role in the early detection of cardiac comorbidities in sleep apnea patients. Sleep Review’s cardiology-sleep solutions column shares new technologies that can help. Email [email protected] with solutions you’d like to see featured here.
Blood pressure cuffs, ubiquitous today, may soon be seen as relics from a time when their spot checks offered too little, too late. New US Food and Drug Administration (FDA)-cleared technology from Bodimetrics with GTCardio Inc boasts a ring–watch combination that measures continuous blood pressure fluctuations overnight, along with peripheral oxygen saturation. The new CirculVS can potentially detect symptoms of cardiovascular diseases that first (or most often) appear during sleep, its developers say, resulting in earlier, targeted interventions that could save lives.
Particularly in the early morning hours when rapid eye movement (REM) sleep dominates, sleep can amplify heart problems. REM-linked bursts in sympathetic and parasympathetic tone are linked to spikes in blood pressure, which can lead to cardiac arrhythmias. Blood pressure fluctuations can also dislodge vulnerable plaque, which can cause heart attacks and strokes. “So a lot of bad things happen during sleep,” says sleep physician Meir H. Kryger, MD, FRCPC, scientific advisor at Bodimetrics. When sleep apnea is also present, “there’s a perfect storm of things that can harm a patient,” says Kryger, a professor emeritus at Yale University.
With CirculVS measuring blood pressure fluctations during sleep, there’s the potential of detecting links between sleep apnea and blood pressure problems in individual patients, Kryger says. At night, blood pressure dips in healthy people, he explains, so seeing it remain the same or increase in someone with sleep apnea is a harbinger of potential heart trouble to come.
“It reminds me of the era when pulse oximetry first came in…all of a sudden, you can measure blood oxygen levels continuously. And that was fabulous,” he says. “And now we can measure important cardiovascular functions…We’ve been able to do the electrocardiogram during the night. But that doesn’t look at the pressures or a possible hypertensive burden. So this is brand new.”
Key Takeaway: CirculVS, a continuous overnight blood pressure monitor, may reveal early cardiovascular risks—especially in patients with sleep apnea—that traditional spot checks miss.
Static Versus Dynamic Blood Pressure
Another limitation of traditional blood pressure cuffs is that they measure what Ehud Baron, MD, DSc, founder and president at GTcardio Inc, refers to as “static” blood pressure. “Static” meaning the cuff artificially occludes blood flow before slowly releasing it. “This is not the right way to know what is happening, like during heart attack or [other cardiac events], because in the heart attack, there is no stopping the blood flow. There is a big flow in the beginning, and this flow has a dynamic or a kinetic energy,” Baron says. Imagine a tsunami, he says, as the high-velocity wave rushes ashore, wreaking havoc on everything in its path.
The developers of CirculVS say these dynamic fluctuations are the most dangerous blood pressure-related vital sign. Though static and dynamic blood pressure are related, they are not the same. Blood pressure cuffs, Baron says, “are not measuring the correct blood pressure.”
The CirculVS provides both static and dynamic blood pressure readings. It combines two FDA-cleared devices, a wrist-worn ambulatory blood pressure monitor and a ring-based pulse oximeter. “The system can actually measure blood pressure continuously, beat by beat,” Kryger says.
Key Takeaway: Traditional blood pressure cuffs miss dynamic, high-risk fluctuations that occur during real-life cardiac events—something the CirculVS aims to capture with continuous, beat-by-beat monitoring.
Early Cardiovascular Disease Detection
Bodimetrics-GTcardio’s mission with CirculVS is to detect cardiovascular disease in the early stages. “The disease that will kill you when you are 70 actually starts when you are 40,” Baron says. “But it progresses slowly.”
Kryger says, “There are conditions where finding out that someone has high blood pressure early on could be really important and potentially life-saving.” One example, he says, is preeclampsia during pregnancy. Instead of waiting for soaring blood pressure and symptoms to require a pregnant woman to rush for an emergency delivery, he asks, “Wouldn’t it be great to be able to measure her blood pressure all night earlier in pregnancy to see whether, in fact, her blood pressure goes up during the night?”
Key Takeaway: Continuous nighttime blood pressure monitoring could enable earlier detection of progressive conditions like cardiovascular disease and preeclampsia, allowing for timely, potentially life-saving interventions.
‘Nocturnal Medicine’
Neil Friedman, chief operating officer at BodiMetrics, says the potential applications of CirculVS go well beyond the medical fields of sleep medicine and cardiology. He says, “When we talk to people, they’re not just interested in this in sleep, but all the different areas and specialties within medicine are now going to have information available to them that they never had.” For example, he is curious whether people with dementia have blood pressure spikes at night—if shown, these fluctuations could become a new treatment target.
“We’re opening a new area, and that’s nocturnal medicine,” Friedman says. “People have not been studied enough during the night, across all specialties of medicine…There’s a huge amount to learn.”
In sleep medicine specifically, Bodimetrics partnered with EnsoData to bring its Circul line to clinicians. Friedman sees potential for a new business model in which a physician could be reimbursed for both the home sleep test and the ambulatory blood pressure monitoring. For long-term management, remote patient monitoring codes could be used. “The most important thing is taking the proper care of their patients, and if there is a new technology out there that is going to give them better insight into the sleep patterns of their patients, let’s take care of them the right way,” Friedman says.
A year and a half ago, the ability to measure blood pressure noninvasively beat-by-beat overnight did not exist, and “I was not even thinking about it,” Kryger says. Now that the technology is here, he is excited to see what it finds. He says, “If I had had something like this 30 to 40 years ago, I would have loved it.”
Key Takeaway: The advent of overnight, noninvasive beat-by-beat blood pressure monitoring opens a new frontier—“nocturnal medicine”—with potential applications across medical specialties and new opportunities for earlier diagnosis, treatment, and reimbursement.
