Smartphone app detects cardiac arrhythmia

Atrial fibrillation is one of the causes for a stroke and often appears without any previous indications. To reduce the risks and provide fast results, the application FibriCheck was invented. With the app it is possible to collect and measure data via smartphone camera.

In an interview with MEDICA-tradefair.com Bieke van Gorp talks about the process of the measurements and further possibilities of using the app with wearables.

How did the application come to life?

Bieke van Gorp: For us, the whole story started with Luc, the father of my co-founder who suffered a stroke due to an undetected atrial fibrillation. Atrial fibrillation is the most common cardiac arrhythmia that is even today still causing approximately 20 percent of all strokes. The difficulty to timely detect atrial fibrillation is due to the fact, that it is often without indications and has an intermittent nature. Even if a person is showing symptoms at one point, by the time they are with a doctor the symptoms might not be showing anymore. Today a stroke itself often is the first symptom. That is the reason why in cooperation with a hospital and a cardiologist center we have been asking: "Can’t we use the mobile devices that are already with the people as a source to detect cardiac arrhythmia?" This question was the starting point for the application back in 2014.

How does the app work?

van Gorp: FibriCheck is an app to detect cardiac arrhythmia. The process itself is quite simple. The user has to put his finger on the camera of his mobile device for 60 seconds to record the pulse rhythm and we take care the rest. With a smart watch it is even easier because the measurements happen automatically at the wrists without the need for any specific user involvement.

How are doctors kept in the loop for diagnosis?

van Gorp: The process usually starts with doctors prescribing the application to their patients. Then patients get an invitation code from the doctor. When they use this code during the registration process a link between the doctor and the patient is established. From that moment onward all measurements are linked and send to the doctor automatically and immediately. The doctor can see all measurements of his patients separately, but since that takes too much time he gets reports when we find something new for a patient that needs attention. They can check the data in a separate web application or integrate it into another system.

How exactly does the app recognize heart rhythm irregularities?

van Gorp: We always need a detector and a light source to recognize cardiac arrhythmia. FibriCheck uses a different measurement technique. The medical application does not focus on the electrical impulses themselves, but on the effect that the beating heart has on blood vessels. With each heartbeat blood flows from the heart in the blood vessels. These waves of blood put pressure on the blood vessel walls and cause them to stretch temporarily. So with each pulse, the diameter of your blood vessels 'enlarges', in between two beats the blood vessel ‘shrinks’ back to its original size.

The FibriCheck app illuminates the fingertip with the flash of the camera of the smartphone and measures the difference in light absorption over time. When the blood vessels are filled with blood right after a heartbeat the absorption will be high. In between heartbeats the amount of blood in the vessels decreases and absorption will be lower. The result of this measurement is called a photophlethysmogram or PPG.

What happens once the data is collected by the app?

van Gorp: Once the data is collected it is automatically sent to a secure sector, which is in Frankfurt in Germany. The app itself is a dumb device, since there is no intelligence formatted on it yet. The data is immediately transmitted to the secured environment and from that moment on analyzed by the algorithm. Within seconds after the measurement the user and the doctor receive feedback on the results.

The app can now be used with a Fitbit smartwatch. Is the app compatible with other wearables as well?

van Gorp: From a technology perspective the application is compatible with smart watches and other future wearables such as earplugs. When the mobile devices or wearables uses PPG sensors FibriCheck can be used. The only thing needed is the raw signal. Sometimes smart watch providers are blocking the raw signal, then the app is not accessible because we can’t use our algorithm for the analysis.

Is the app user-friendly for elderly people?

van Gorp: When we started in 2014 it was not as common to measure data with apps for elderly people of the age 60 or above. But since then more and more people over 60 started using a smartphone. We develop our app together with patient groups to make sure, that it is easy to use for elder target groups as well. Today we have over 200.000 people that have used FibriCheck. The average age of users is 50+ with 60 percent of all users. Smart watches are further advancing the usage, because they just need to be worn to monitor the person.

FibriCheck has already been on the market for quite some time. What are some of your future goals?

van Gorp: From a commercial perspective, we focus on internationalization. Since we are doing a lot of work in the UK, on the Italian market and starting in the German market as well. We have the FDA Approval for the US market so we will be further expanding in that area.

From a technology perspective, we are focusing on continuously monitoring heart rhythm via smartwatch on the wrists. In one to four months we want to provide a solution that can automatically monitor the heart rhythm at night without any involvement of the user.