A research team from the University of Bonn has succeeded for the first time in using light stimuli to stop life-threatening cardiac arrhythmia in mouse hearts. Furthermore, as shown in computer simulations at Johns Hopkins University, this technique could also be used successfully for human hearts. The study opens up a whole new approach to the development of implantable optical defibrillators, in which the strong electrical impulses of conventional defibrillators are replaced by gentler, pain-free light impulses. The "Journal of Clinical Investigation" has now published the results.
! When the heart muscle races and no longer contracts in an orderly fashion, sudden death often follows due to the lack of blood circulation. In such an emergency, a defibrillator helps to restore normal heart activity by means of intense electrical shocks.
In patients with a known risk for these arrhythmia, the prophylactic implantation of a defibrillator is the treatment of choice. If ventricular fibrillation is detected, a pulse of electricity is automatically generated, which normalizes the excitation of the heart muscle and saves the person's life.
"When an implanted defibrillator is triggered, which unfortunately can also happen because of false detection of arrhythmia, it is always a very traumatic event for the patient", says the head of the study, Junior-Professor Philipp Sasse of the Institute of Physiology I at the University of Bonn.
"The strong electrical shock is verVentricular fibrillationy painful and can even damage the heart further". Therefore, Professor Sasse's team investigated the principles for a pain-free, gentler alternative. As the scientists have now shown, ventricular fibrillation can be stopped by optical defibrillation.
Optical defibrillation requires gene transfer
The team used the new method of "optogenetic" stimulation of mouse hearts, which had genes inserted for so-called channelrhodopsins. These channels are derived from a green algae and change the ion permeability of heart cell membranes when illuminated. When the researchers triggered ventricular fibrillation in the mouse heart, a light pulse of one second applied to the heart was enough to restore normal rhythm. "This is a very important result", emphasizes lead author Dr. med.
Tobias Brügmann of Professor Sasse's team. "It shows for the first time experimentally in the heart that optogenetic stimulation can be used for defibrillation of cardiac arrhythmia". It also worked in normal mice that received the channelrhodopsin through injection of a biotechnologically-produced virus. This shows a possible clinical application, because similar viruses have already been used for gene therapy in human patients.
Simulations show that findings could be applied to patients
But are the findings with mouse hearts applicable to humans? In order to answer this question, the scientists at the University of Bonn are working together with Prof. Natalia Trayanova’s Computational Cardiology Lab at the Institute for Computer Medicine and the Department of Biomedical Engineering at Johns Hopkins University (Baltimore, USA). There, optogenetic defibrillation is being tested in a computer model of the heart of a patient after cardiac infarction.
"Our simulations show that a light pulse to the heart would also stop the cardiac arrhythmia of this patient", reports Research Professor Patrick Boyle, who is also a lead author. To do so, however, the method from the University of Bonn had to be optimized for the human heart by using red light to stimulate the heart cells, instead of the blue light used in mice. This aspect of the study demonstrates the important role that can be played by computational modelling to guide and accelerate the systematic development of therapeutic applications for cardiac optogenetics, a technology that is still in its infancy.
Implantable optogenetic defibrillators could be feasible
"Our data show the fundamental feasibility of optogenetic defibrillation for the treatment of ventricular fibrillation", summarizes Prof. Sasse. Using light to return the fibrillating heart to a normal rhythm can be expected to be pain-free and much gentler for the patient than the use of electric shock. However, the new method is still in the stage of basic research. Until implantable optical defibrillators can be developed for the treatment of patients, it will still take at least five to ten years, estimates Prof. Sasse.
Publication: Optogenetic defibrillation terminates ventricular arrhythmia in mouse hearts and human simulations, "Journal of Clinical Investigation", DOI: 10.1172/JCI88950
Contact for the media:
Junior Prof. Philipp Sasse
Institute of Physiology I
University of Bonn
Dr. Tobias Brügmann
Institute of Physiology I
University of Bonn
Johannes Seiler | idw - Informationsdienst Wissenschaft
A first look at interstitial fluid flow in the brain
05.07.2018 | American Institute of Physics
A sentinel to watch over ocular pressure
04.07.2018 | Fraunhofer Institute for Microelectronic Circuits and Systems
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences