New low-energy cardiac defibrillation method developed
15 July 2011
An international team of scientists 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% compared to the current conventional
method. Their discovery opens the path for the painless therapy of
life threatening cardiac fibrillation.
The researchers are 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).
The results are describe their results in the current issue of
In a 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.
Spatial-temporal excitation pattern during
cardiac fibrillation on the surface of heart (field of view 6 x 6
cm2). Colour code: black = resting, yellow = excited. Credit: MPI
for Dynamics and Self-Organization
For 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”, says
Luther describing the team’s newest results.
Even though LEAP and standard defibrillation seem to work
similarly at first sight, they initiate completely different
processes within the heart. “The classic defibrillator works by
using a very strong electric field that excites all cells of the
organ. In contrast, LEAP uses low-energy pulses to synchronize the
tissue”, says Fenton. 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. The
situation can be compared to turning a malfunctioning computer off
and on again,” says Robert Gilmour from Cornell University.
The 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.
In principle, the results also apply for defibrillation of
ventricular fibrillation, a life-threatening arrhythmia, which is
terminated only by external and 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 exchanges.
"The 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; the 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, the head of the Heart Center Göttingen.
Stefan Luther, Flavio H. Fenton, Bruce G. Kornreich, Amgad
Squires, Philip Bittihn, Daniel Hornung, Markus Zabel, James
Flanders, Andrea Gladuli, Luis Campoy, Elizabeth M. Cherry, Gisa
Luther, Gerd Hasenfuss, Valentin I. Krinsky, Alain Pumir, Robert F.
Gilmour Jr., Eberhard Bodenschatz. Low-energy Control of Electrical
Turbulence in the Heart. Nature, 14 July 2011.
This work was supported by the Max Planck Society, the National
Science Foundation (#0800793 and #0926190); the National Institutes
of Health; by IFCPAR; by BMBF; by the Kavli Institute for
Theoretical Physics and by the European Community's Seventh
Framework Programme FP7/2007–2013 through HEALTH-F2-2009-241526