An international team of scientists from the Max-Planck-Institute
for Dynamics and Self-Organization (Göttingen, Germany), Cornell University
(Ithaca, New York), the Ecole Normale Supérieure de Lyon (France), the University
Medicine Göttingen (Germany), the Rochester Institute of Technology (USA), and the
Institut Non-Linéaire de Nice (France) has developed a new low-energy method
for terminating life-threatening cardiac fibrillation of the heart. They have shown that their new technique called
LEAP (Low-Energy Anti-fibrillation Pacing) reduces the energy required for
defibrillation by more than 80% as compared to the current conventional method.
Their discovery opens the path for the
painless therapy of life threatening cardiac fibrillation. The scientists
describe their results in the current issue of Nature.
(Nature, published July 14, 2011)
healthy heart, electrical pulses that propagate across the heart muscle in an
orderly fashion control the organ’s movements: at regular intervals the heart’s
ventricles and atria contract and relax again. In the case of cardiac
arrhythmia, however, this does not work reliably. Here, electrical pulses may propagate
throughout the heart chaotically, disabling the regular heartbeat and thus
preventing the body from being properly supplied with blood. The most common cardiac arrhythmia is atrial
fibrillation, which affects more than 10 million people in Europe and US.
patients suffering from chronic atrial fibrillation there is one reliable solution:
a defibrillation. A strong electric
pulse, which patients perceive as painful and which can damage the surrounding
tissue, forces the heart back into its regular beating. The international team of scientists led by
Stefan Luther from the Max Planck Institute and Flavio Fenton from Cornell
University has proposed a new method. Using
a cardiac catheter the researchers create a sequence of five weak electrical
signals in the heart. Only a few seconds
later, the heart beats regularly again.
“LEAP requires 84% less pulse energy compared to conventional defibrillation”,
says Luther describing the team’s newest results.
though LEAP and standard defibrillation seem to work similarly at first sight,
they initiate completely different processes within the heart. The classical defibrillator works by using a
very strong electric field that excites all cells of the organ. "For a short moment they can no longer
transmit any electrical signals; the chaotic activity is terminated. Afterwards, the heart resumes its normal,
regular beating", says Robert Gilmour from Cornell University. The situation can be compared to turning a
malfunctioning computer off and on again. "In contrast to standard defibrillation,
which applies a painful and potentially damaging high-energy shock to terminate
all electrical signals at once, LEAP uses a sequence of low-energy pulses to
progressively synchronize the tissue”, says Fenton.
new method terminates the turbulent electric activity within the heart step by
step. “Our most important allies are
natural heterogeneities within the heart such as blood vessels, fatty tissue or
fibrotic tissue”, says Eberhard Bodenschatz from the Max Planck Institute. In experiments and computer simulations the
researchers were able to show that these heterogeneities can act as the origins
for synchronizing waves. “Quite weak
electrical pulses suffice to stimulate the cells in these regions”, says Alain
Pumir from Lyon. With every additional
pulse more heterogeneities are activated thus gradually suppressing chaotic
activity. “The heterogeneities act as
small control sites that – once activated – can “reprogram” the entire organ”,
adds Valentin Krinsky from Nice.
principle, the results also apply for the termination of ventricular
fibrillation, a life-threatening arrhythmia, which is terminated only by
external or implantable defibrillators. For
a large number of patients wearing implantable cardioverter-defibrillators
(ICD) the new technique may eliminate pain, improve the success rate of treatment,
prolong battery life and therefore reduce the need for surgical device
development of LEAP is a groundbreaking result and an outstanding example of
successful interdisciplinary collaboration between physicists and
physician-scientists, with immediate impact on the development of novel
therapies for life-threatening cardiac arrhythmias“, says Markus Zabel from the
University Center Göttingen. The ideas
leading to LEAP were first developed by asking elementary physical questions
about the interaction between electric field and cardiac tissue; these results
of earlier theoretical work in physics, in particular in the French National
Center for Scientific Research (CNRS), may be finding their way to clinics. Indeed, “we are working to get this to the
patient as fast as possible”, adds Gerd Hasenfuss, head of the Heart Center
work was supported by the Max Planck Society, the National Science Foundation
(#0800793 and #0926190); the National Institutes of Health; by IFCPAR; by BMBF
(FKZ 01EZ0905/06); by the Kavli Institute for Theoretical Physics and by the
European Community's Seventh Framework Programme FP7/2007–2013 agreement HEALTH-F2-2009-241526
S. Luther & F.H. Fenton et al., Low-energy Control of Electrical Turbulence in the Heart, Nature 475, 235-239 (2011).
R.A. Gray and J.P. Wikswo, Cardiovascular disease: Several small shocks beat one big one, Nature 475, 181-182 (2011).