Remember only your doctor can tell you about your medical options. That however does assume your doctor knows about the available options. As a former project manager once told her group, never assume, 'That just makes an ass out of u and me' e.g. ass-u-me. Good luck treating your doctors lack of knowledge.
http://www.alphagalileo.org/ViewItem.aspx?ItemId=143268&CultureCode=en
Cardiac optogenetics achieve defibrillation without the pain of electric shocks
The
first evidence for a shockless treatment for atrial fibrillation (AF)
will be presented today at Frontiers in CardioVascular Biology (FCVB)
2014 in Barcelona, Spain. The meeting is organised by the Council on
Basic Cardiovascular Science of the European Society of Cardiology (ESC)
in collaboration with 13 European cardiovascular science societies.
http://spo.escardio.org/SessionDetails.aspx?eevtid=65&sessId=13104
Dr
Brian O. Bingen, first author, said: “AF is the most common cardiac
arrhythmia. Symptoms range from the feeling of fish flapping in the
chest, to tiredness and exercise intolerance. AF can lead to tachycardia
induced cardiomyopathy and thromboembolic events which increase the
risk of morbidity and death.”
He added: “Preventing these
symptoms and complications requires bringing the patient out of AF and
back to the normal sinus rhythm. The quickest way to do that is to
deliver an electric shock. The shock depolarises and synchronises the
heart muscle and allows the sinus node to re-establish a normal rhythm.”
Dr
Bingen continued: “Shocks are currently the most effective way to get
patients directly back into sinus rhythm but they are very painful. To
deliver a shock you have to give anaesthesia which comes with its own
possible adverse effects.”
AF usually progresses from a
paroxysmal form, in which episodes of AF last from several minutes up to
7 days, to a persistent and eventually a chronic form. People with the
latter are in AF 24 hours a day, 7 days a week, and shock treatment no
longer works. Dr Bingen said: “AF causes structural changes to the
atrium which make patients more prone to subsequent induction of AF.
That’s another reason to get patients back into sinus rhythm as soon as
possible.”
For the current study, the researchers devised a
method of shockless defibrillation. They used optogenetics to
genetically insert depolarising ion channels into the heart that can be
activated by light. Dr Bingen said: “The theory was that we could just
turn a light switch on and depolarise the entire myocardium without
needing a shock. In theory, the patient could be given an implantable
device with a mesh of light emitting diodes (LEDs) and when AF occurs
you turn the light on and the AF stops.”
During arrhythmias there
is activity subepicardially but the heart is a complex 3D structure and
it is only possible to directly observe the epicardium (outside layer).
To see how their method worked subepicardially, the researchers
developed 2D hearts. They isolated cardiac muscle cells from the rat
atrium, replated them in a culture dish and allowed the cells to form
intercellular connections, creating a 2D heart.
AF was induced in
31 of these 2D hearts. The researchers used a lentivirus to insert a
gene into the 2D hearts called calcium-translocating channelrhodopsin
(CatCh), which is a light sensitive depolarising channel.
Dr
Bingen said: “Then it was just a matter of switching on the light and
seeing what happened. We found that in all 31 of these 2D hearts we were
able to achieve the 2D equivalent of cardioversion into sinus rhythm.
The mechanism we saw was a bit different than the normal defibrillation
but was equally effective.”
He continued: “We now have to test
our method in the 3D setting. In that scenario we won’t be able to see
the defibrillating mechanism in as much detail, but we hope that it will
be possible to terminate AF in the complete heart. We will also test
other types of light or energy sources that penetrate the body more
deeply and could be applied externally, avoiding the need for an
implanted device.”
Dr Bingen continued: “This is the first
evidence of a shockless defibrillation. Our method of using optogenetics
to defibrillate by light is completely painless and looks promising but
more research is needed before it can be applied in patients.”
Please note Spanish version is available for this Press Release
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