Rather than relying on painful electric shocks, a new method of treatment is being studied in which light would be used to achieve defibrillation in patients with atrial fibrillation.
In Barcelona, Spain, at the Frontiers in CardioVascular Biology 2014 conference, the first evidence for this potential new treatment for atrial fibrillation will be unveiled.
Atrial fibrillation (also known AF or A-Fib) is an irregular heartbeat or arrhythmia that is the most common serious heart rhythm abnormality in people over 65. When it occurs, the upper chambers of the heart (the atria) beat irregularly, resulting in a less effective flow of blood to the lower chambers (the ventricles).
A global health problem
Atrial fibrillation is a condition where the heart beats irregularly. It is the most common serious heart abnormality in individuals over the age of 65 in the US.
According to the American Heart Association (AHA), an estimated 2.7 million Americans have the condition. Untreated AF doubles the risk of heart-related death and makes the chances of stroke around 5 times as likely. 15-20% of people who have strokes also have AF.
Recently, Medical News Today reported on a study that had found that hospitalizations and health care costs for AF both rose between 2001 and 2010. The researchers noted that atrial fibrillation was likely to "become a major burden on hospitals."
In order to prevent the symptoms of AF developing further, the patient needs to be brought back to a normal heart rhythm. At present, the quickest and most effective way to do this is via an electric shock.
AF can affect the atria structurally as well, making them more prone to subsequent inductions. The condition can progress from episodes lasting several minutes to a situation where patients are permanently in AF and shock treatment is no longer effective.
Despite the risks, many patients are unaware of how dangerous AF is. According to the "Out of Sync" survey in 2009, only 33% of patients with AF believe that it is a serious condition. Less than 50% believe they have an increased risk of heart-related hospitalizations, stroke or death.
'First evidence of shock less defibrillation'
Dr. Brian O. Binger is first author of the research into the new method of defibrillation. He says that the electric shock method is very painful, and "to deliver a shock you have to give anesthesia which comes with its own possible adverse effects."
As an alternative, the researchers came up with a method that uses optogenetics - a technique that activates neurons by shining light on them - in order to reset the heartbeat. They genetically inserted depolarizing ion channels that could be activated by shining light into the heart. Dr. Binger explains:
"The theory was that we could just turn a light switch on and depolarize the entire [heart muscle tissue] 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 could turn the light on and the AF stops."
During AF, there is activity in the heart beneath its outside layer (epicardium), but it is not normally possible to observe it. The researchers had to develop some 2D hearts using isolated cardiac muscle cells from rats in order to fully see how their method worked below the epicardium.
The researchers induced AF in 31 2D hearts. They inserted a gene into the hearts called calcium-translocating channelrhodopsin (CatCH), a light sensitive depolarizing channel, and would then turn on a light to try and defibrillate.
In all 31 of the 2D hearts, they were able to achieve full restoration of the heartbeat back to a normal rhythm.
Dr. Bingen now looks ahead to the next stage of their research:
"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."
He believes that the early results look promising, but is aware that these are still the beginning stages of the project.
AF is a condition that the World Health Organization considers to be a growing global health problem, as reported by Medical News Today. If successful, this new branch of research could prove to be a game-changer in treating the condition.
Written by James McIntosh