Listening to the heart’s weak electrical currents
A group of “electricians” at LTH have specialised in studying the weak electrical currents inside our bodies and are helping physicians to develop methods of analysis to examine heart function.
“We work with signal processing and try to better understand the heart; we map what is not visible to the naked eye. We extract information with measuring methods and mathematics. You could see it as working with a sort of microscope to find clinically interesting properties among the signals”, says professor Leif Sörnmo, who heads the team working on bioelectrical signal processing.
Electrodes and ECG (electrocardiogram) are just one among many ways of measuring the heart’s activity today. There are methods that we can use at home, such as an Iphone app which measures the pulse through the light in your thumb, specially designed measuring rods and a Swedish-design thumbplate for ECG. Atrial fibrillation – the most common cardiac arrhythmia particularly in men – can also be measured in the Iphone app and quickly analysed in a cloud service. New technology gives researchers enormous amounts of data to work with, making it easier to evaluate new methods. Reader Martin Stridh, who is working on this, has over 80 000 patients in his data from thumb ECGs.
The team comprises around ten researchers within EIT, the Department of Electrical and Information Technology. They are interested in developing new methods, for which they cooperate closely with physicians in Lund and within a large international network. Cardiologist Pyiotr Platonov is the most important cooperation partner at SUS (Skåne University Hospitals) at the moment. Clinical physiologists also cooperate with the team.
“We hope to be able to help cardiologists with patients suffering from atrial fibrillation, by determining what treatment is most appropriate for each individual, for example. Sometimes it is helpful to burn away heart cells by introducing a catheter, but not always. We work with methods to facilitate the treatment decision. Our findings have been published, but the steps to get the method out into clinics are long”, says Leif Sörnmo.
“One area that interests us is to examine kidney patients during dialysis. The heart is put under strain by dialysis but it is complicated for all parties to measure ECG during the process. Directly from the dialysis machine, we can extract significant information about the heart: heart rate, atrial fibrillation, dysrhythmias. Here we cooperate closely with Gambro, via Mattias Holmer who is doing an industry-based PhD funded by the Swedish Research Council, among others.”
Micropotentials in ECG can be realised through signal processing in spite of the fact that we are dealing with such weak currents that they are not “visible to the naked eye”, as Leif says. The heart is far from the only organ in the body to emit electrical signals. Researchers apply great effort to distinguishing the heart’s signals from those of other muscles in the body, for example. This is done in cooperation with physicians, mainly from the cardiology clinic in Lund, but also through many international cooperation initiatives. The research started as early as the 1970s with Leif’s predecessor Per-Ola Börjesson and clinical physiologist Olle Pahlm as the originators of the idea.
There are plenty of unresolved issues in the bioelectrical field. Arrhythmias of other kinds can be treated with pacemakers or defibrillators.
Text: MATS NYGREN