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Sudden cardiac death. Right-wing hurricanes in the heart
Every five minutes alone a person dies of a sudden cardiac death. Cardiac arrest is caused by ventricular fibrillation - a severe cardiac arrhythmia. Doctors still do not understand in detail what exactly happens in the heart. So far, physicians have not been able to visualize the dynamic processes in the flickering heart muscle. For the first time, a new research work has brought astounding findings to light.
When ventricular fibrillation, the pumping power of the heart is life-threatening and there is a threat of sudden cardiac arrest. (Image: spkphotostock / fotolia.com) In today's publication of the journal Nature, an international team of researchers led by Jan Christoph and Stefan Luther from the Max Planck Institute for Dynamics and Self-Organization and Gerd Hasenfuß from the Heart Center of the University of Göttingen show for the first time how vertebral rotating contractions underlying life-threatening atrial fibrillation occur Inside the heart can be observed. They use a new imaging technique for which ultrasound devices that are well established in medicine can be used. Doctors will be better able to examine cardiac arrhythmias, as well as other heart diseases, and to develop new treatment methods.
On the core of ventricular fibrillation: from ultrasound images (left) Max Planck researchers reconstruct how the heart muscle in a cardiac arrhythmia contracted vertebral (center). You can also locate the filaments (right) that form the cores of the vertebrae. These insights provide starting points for improved therapies.
When the heart muscle no longer contracts in a coordinated manner, but only flickers, it becomes life-threatening. Doctors speak of a fibrillation. If the main chambers of the heart twitch in this disorderly way, there is only one salvation: The heart muscle has to be defibrillated within a few minutes with a strong current surge, which is very painful and can damage the heart tissue. Atrial fibrillation, on the other hand, does not lead directly to death, but if left untreated, can also have fatal consequences. "The key to a better understanding of fibrillation lies in a new high-resolution imaging, with which the processes can also be observed inside the heart muscle," says Stefan Luther, head of the research group "biomedical physics" at the Max Planck Institute for Dynamics and Self-organization and professor at the University Medical Center Göttingen.
"The mechanical movement of the heart muscle in fibrillation is highly complex, but it is also very characteristic - almost like a fingerprint of fibrillation," says Jan Christoph, a researcher at the Max Planck Institute for Dynamics and Self-Organization and the German Center for cardiovascular research in Göttingen and lead author of the study. Together with Stefan Luther and an international team of researchers, the physicist is now presenting a diagnostic method with which the flickering of the heart muscle can be examined in a time-resolved manner in three dimensions with a conventional ultrasound device and thus much more accurately than was previously possible in the patient.
Helpful for diagnosis and therapy of heart failure
3D ultrasound measurements of mechanical filaments in the fibrillating heart
The new diagnostic method will help to make the treatment of ventricular fibrillation and possibly atrial fibrillation more effective. Thus, a better understanding of the fibrillation that can be achieved with the procedure will help advance the development of low energy defibrillation. This weaker, but much more targeted power surges to end the ventricular fibrillation than in today's usual painful defibrillation with high-energy electric shock. With the new form of ultrasound diagnostics, medical professionals can figure out how to use the lower energy surges to get the heart back to normal.
The Göttingen researchers are also developing the method so that it also visualizes the complex arousal dynamics in atrial fibrillation. In the future, cardiologists will be able to see at what points they should become obliterated by ablation of pathological centers of excitement. The new ultrasound method should also be helpful for the research, diagnosis and treatment of myocardial insufficiency. The heart muscle cells are ineffective because their coordinated contraction is disturbed. The reasons for this could be found in doctors with detailed ultrasound scans, so they can detect heart failure earlier and treat it more effectively.
Electrical stimulation causes mechanical contractions of the heart
Computer simulation of an electromechanical vertebra in cardiac muscle tissue
Computer simulation of an electromechanical vertebra in cardiac muscle tissue
Each heartbeat is triggered by electrical waves of excitation, which shoot through the heart muscle at high speed, causing the heart muscle cells to contract. If these excitation waves get mixed up, cardiac arrhythmias arise. For some time, physicians have been aware that cardiac arrhythmia causes electrical stimulation to travel through the heart muscle in a whirling pattern. So far, they have focused on these electrical vertebrae in the study of cardiac arrhythmias. But they could not give a complete picture of the dynamics in everyday medical life. The Max Planck researchers now took a different approach and instead of the electrical stimulation, looked at the twitching contractions of the flickering heart muscle. "So far, little importance has been attached to the analysis of muscle contractions and deformations during fibrillation. In our measurements, however, we saw that the electric vortex always occurs with corresponding vortex-shaped mechanical deformations, "says physicist Jan Christoph.
To illustrate the trembling movements inside the heart muscle in three dimensions and to correlate with the electrical excitation of the heart, the researchers developed new high-resolution ultrasound measurement methods. They also demonstrated that these methods can be used in high-performance ultrasound machines that are already routinely used in many cardiology institutions. By analyzing the image data of the muscle contractions, they were able to follow in a flickering heart exactly how areas of contracted and relaxed muscle cells move in a vortex through the heart muscle. They also observed filamentous structures that physicists were previously known only in theory and from computer simulations. Such a filamentous structure resembles a thread and marks the eye of the hurricane moving through the heart muscle. Locating the centers of the vertebrae inside the muscle is now possible for the first time.
In addition to the ultrasound recordings, the researchers used high-speed cameras and fluorescent dyes, which visualize the electrophysiological processes in the heart muscle. The images thus obtained confirmed that the mechanical vortices reflect the electric vortices very well.
Potential to revolutionize the treatment of cardiac arrhythmias
Electric whirl on the heart surface
According to the Göttingen researchers, ultrasound technology has undergone tremendous development in recent years in terms of image quality and recording speeds - the potential of modern ultrasound technology has not yet been fully exploited. "Together with the immensely increased computing power of modern computers and the rapid advances in computer graphics and digital image processing, completely new measurement and visualization possibilities open up in the heart. We can use these developments in medicine today, "says Jan Christoph.
The study is an example of successful interdisciplinary cooperation between physicists and physicians in the German Center for Cardiovascular Research. "This development has the potential to revolutionize treatment options for patients with cardiac arrhythmias. As early as 2018, we will be using the new technology in our patients in order to better diagnose and treat cardiac arrhythmias as well as heart muscle diseases, "says Gerd Hasenfuss, co-author of the study, chairman of the Göttingen Heart Research Center and the Heart Center of the University Medical Center Göttingen. Stefan Luther is certain: "A deep look into the inner dynamics of the heart is a milestone in heart research and will decisively shape the understanding and treatment of heart disease in the future." MPIDS / PH