Heartfelt it is possible to recognize the risk of sudden death from the variation in heart rate, says the team of physicists at the University of Tampere.
“The risk of sudden cardiac death can be estimated from a couple of minutes of resting heart rate based on heart rate variability even more accurately than with a traditional cardiological stress test,” says the director of the Monicardi project, professor of physics Esa Räsänen.
This was revealed in a recent study that is currently undergoing peer review. The mathematical analysis method also detects heart failure and a prolonged QT interval from the heart rate, which can easily lead to arrhythmias.
The variation in heart rate is about the fact that the heart never beats at a steady pace. If the heart rate is 60 times per minute, the interval between the beats is not exactly one second, but it varies continuously.
Group is developing a commercial software application based on its algorithms that could work in medical devices, but also in sports watches and smart rings used by ordinary people.
“Anywhere, that measures heart rate,” says Räsänen.
He sees great potential in applications. “Almost everyone uses these devices, but the data is not utilized.”
What would be the benefit of constant self-observation in practice?
Räsänen says that, for example, the disease of a diagnosed heart patient could be monitored in real time and unnecessary follow-up visits to the doctor could be dispensed with. Instead, the device could refer to a doctor as soon as there is a reason for it.
More obscure is what kind of information the app should provide to the average sports watch user.
“The device can’t tell you that you’re going to die.”
5,000–10,000 people experience sudden cardiac death each year.
The user should also not have to interpret the information himself. According to Räsänen, a thorough discussion with medical experts is needed to solve the questions.
Smart watch brands Garmin and Apple Watch have already entered the field with applications that inform the user of the watch about atrial fibrillation.
Already small heart rate variability is known to predict mortality in heart disease. It has been shown in several follow-up studies.
According to Räsänen, his group has gone further and is not just measuring the magnitude of the variation. The method is able to examine the characteristics of variation and how they change from moment to moment.
In a healthy person, there are large and small changes in the variation in an appropriate ratio, which affect future changes. If these effects disappear, something is wrong.
In patients suffering from the same heart problems, the characteristics of heart rate variability have changed in the same way. This is how a person is identified as belonging to a certain disease profile.
RäsäNen ended up in the world of heart disease through twists and turns. For a long time, his research focused on computational quantum physics.
Surprisingly, it turned out that the same methods can be applied to complex time series. The variation in heart rate intervals produces exactly those.
First, however, Räsänen began to study music. He found that drummers’ rhythms have the same fine, irregular variation as a heartbeat.
“It makes the music pleasant and groovy,” says Räsänen.
The jump to heart beat intervals happened when Räsänen was in 2012 at a public event to make the public aware of the Nobel Prize received by quantum physicists. On the same occasion, a cardiologist Katriina Aalto-Setälä told how stem cells differentiated into heart cells beat almost regularly.
Räsänen woke up to the word nearly. That was the beginning of the cooperation with Tays cardiologists.
“So this is the sum of coincidences.”
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An exercise application could determine the heart rate limits that are important for athletes and avid exercisers.
Sports watches and other portable heart rate measuring devices already monitor the variation of the heart rate interval and, based on that, tell about the user’s stress and recovery.
In many of them, the Finnish Firstbeat software is ticking, which was developed 20 years ago by researchers from the Research Center for Racing and Elite Sports and the University of Jyväskylä.
The basis of the invention was the observation that, when stressed, the variability of the heart rate also decreases. If the variation in heart rate is wide at rest, it means that the person is not stressed but is recovering.
A company is also planned to be established in the Monicardi project in Tampere. The project receives support from Business Finland.
However, the commercialization of applications related to heart health may take time due to strict regulation.
The first finished product can be an exercise app that determines the heart rate limits important to athletes and avid exercisers.
So Endurance training would be effective, it must be done with suitable power. Exercising at too high a heart rate does not develop basic endurance. Speed endurance, on the other hand, must be practiced with sufficiently hard power.
The correct heart rate ranges are individual and change as fitness increases. Laborious and expensive tests are needed to determine them. Heart rate limits are measured at the test station from blood samples or breathing gases, when the person being tested stretches himself to exhaustion.
Easier the alternative has been to calculate the heart rate limits based on the maximum heart rate, but the calculation formula does not give the right result, especially for top-fit athletes.
The Tampere group has also succeeded in identifying these endurance training thresholds based on heart rate variability.
Thanks to the new application, even an ordinary exerciser could determine the heart rate limits themselves with a sports watch or a smart ring.
Threshold values calculated from heart rate intervals corresponded well to those measured from blood lactates. However, the study has only been conducted with 15 test subjects, and the result must be confirmed with a significantly larger group, says Räsänen.
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