A new biologically integrated defibrillator can correct cardiac arrhythmias without the painful electric shock of traditional cardioversion. The device, known as the BioICD, combines gene therapy, light-sensitive heart cells and implantable LED technology. The approach has now been successfully tested on rats.
Cardiac arrhythmias are mainly treated with medication, ablation or electrical cardioversion, depending on their nature and severity. The most common cardiac arrhythmia in the Netherlands is atrial fibrillation; it is estimated that around 300,000 people in the Netherlands suffer from this condition. If other treatments prove ineffective, cardioversion may be necessary for atrial fibrillation.
In electrical cardioversion, the heart’s rhythm is restored using a powerful electrical impulse. Patients are usually conscious during an arrhythmia. The procedure is therefore generally carried out under general anaesthesia. An implantable defibrillator, such as an ICD, is by no means always an alternative in cases of atrial fibrillation.
Biological electricity
With the BioICD, however, researchers at the LUMC and Delft University of Technology are taking a different approach. The human heart naturally generates a constant stream of electrical signals, which control the contraction of heart cells. The researchers aim to use this so-called biological electricity to restore a disrupted heart rhythm.
The BioICD uses small LED light sources that can emit light at specific times and locations. To achieve this, the heart tissue must first be made light-sensitive. Gene therapy is used to introduce proteins into heart cells that react to light and subsequently generate an electrical signal. By controlling the intensity, timing and location of the light, the researchers aim to identify which electrical stimuli are required to terminate an arrhythmia.
Successfully tested in rats
Researchers at the LUMC and Delft University of Technology are working on small LED systems that can be implanted in the body and emit controlled light. The principle has now been successfully tested in rats. The next step in the research is to test the technology in pigs. Before such a treatment can be investigated in humans, further pre-clinical studies and extensive safety and efficacy trials are required.
In addition to animal studies, the researchers are using cultured human heart tissue to investigate the effects of light-controlled stimulation. This tissue is cultured using donated heart tissue. This creates a layer of tissue comparable in size to the atrial tissue of the human heart.
This larger model offers interesting possibilities. For example, the behaviour of heart cells depends, amongst other things, on the scale and interconnections within the tissue. The researchers can induce arrhythmias in a controlled laboratory setting and then treat them using various light patterns and LED configurations.
The LUMC has human cell lines that have been developed from donated heart tissue. These cell lines can be reused time and time again for research. The LUMC describes them as ‘unique human cell lines that may be of interest for both academic and commercial research’.
Automatically detecting and treating arrhythmias
As a next step, the researchers want to focus on automatically detecting an arrhythmia and, based on this, activating the implantable LED system. To this end, they are investigating, amongst other things, a wearable device for detecting an abnormal heart rhythm, such as a smartwatch. Via a wireless connection, this device can then activate an implanted receiver, after which the LEDs deliver targeted stimulation to the heart tissue.
In the longer term, the researchers are focusing on an even more advanced form of biological defibrillation, in which the heart itself detects and terminates an arrhythmia. “The ultimate goal is for the heart itself to recognise and stop an arrhythmia. Without electronics or light, but entirely biologically and without shocks. The heart as its own defibrillator,” says Daniël Pijnappels, Professor of Cellular Electrophysiology at LUMC.
