Sensor Belt Measures Longest ECG Ever

Karlsruhe Institute of Technology, Karlsruhe, Germany

www.kit.edu/english/

Patients with cardiac diseases may ignore symptoms for months before an emergency arises. Then, seconds count. A long-term recorded electrocardiogram (ECG) may help physicians determine if an emergency is pending. A sensor belt developed at Karlsruhe Institute of Technology (KIT) for the first time allows physicians to document cardiac activity of a patient over a long period around the clock for up to six months.

Fig. 1 – The sensor belt reliably monitors cardiac activity and other parameters over a long period of time. (Credit: KIT)

“The sensor belt also detects very rare cardiac events and, hence, helps find an appropriate therapy,” Wilhelm Stork of KIT explains. The device measures a number of parameters, such as cardiac and breathing frequency, activity, and conductivity, continuously over a very long term and records an ECG. “Then, the doctor has all the data he needs to help the patient early so that no emergency develops.”

How It Works

The sensor belt contains four novel dry electrodes that collect reliable measurement data. The patient can put on the belt himself. “The belt resembles known pulse monitors for joggers and also looks similar. However, it records far more data,” Malte Kirst, one of the developers at KIT, says. The measurement electronics are about the size and weight of a small mobile phone. Over one week the unit acquires more than one gigabyte of data. Then, the memory card is read out and the accumulator is recharged. “Due to the special design and data evaluation, a usable ECG is recorded for about 99 percent of the time, even when single electrodes fail as a result of body movement, for instance,” Kirst says.

Conventional mobile ECG measurement devices require conductive pastes. The self-adhesive electrodes are attached precisely to the skin by medical staff. Often, skin irritations occur after some days or the paste dries out. As a rule, data records for 24 hours, sometimes for seven days. In the case of high-risk patients, the measurement devices used for monitoring may also be surgically implanted. The new sensor belt combines the advantages of both systems.

Since chronic cardiac insufficiency is one of the most frequently occurring cardiovascular diseases affecting more than 10 million people in Europe, the disease costs billions of dollars in healthcare due to intensive treatment of emergencies and subsequent long stays at hospitals. Therefore, it is highly beneficial for both patients and the healthcare system to diagnose beginning cardiac failure (decompensation) and to initiate treatment early. Continuous monitoring with the sensor belt, for example, or another device, can predict decompensation so that appropriate measures can be taken in time.

The sensor may also be applied to diagnose atrial fibrillation and syncopes, i.e., spontaneous loss of consciousness, which affect about 400,000 patients in Germany. For these, reliable, long-term ECGs are required in order to identify or exclude the heart as the cause.

What’s Next

A team of four researchers is currently working on turning the sensor belt prototype into a medical product for this application. Under the Exist programme of the Federal Ministry of Economics, the development work was funded with EUR 500,000.

The researchers tested the long-term usability of the sensor belt at KIT, the Karlsruhe Municipal Hospital, and the University Hospital of Tübingen. About 50 people took part and wore the belt from several days up to a few weeks, with about two weeks on average. Before, the patients had suffered from an acute cardiac insufficiency. In the post-treatment phase, the sensor belt was applied for continuous monitoring. One test person was monitored for a continuous period of six months.