Nav: Home

'Digitizing' crosstalk among heart cells may help locate epicenters of heart rhythms

March 10, 2015

A team of scientists led by Johns Hopkins cardiologist and biomedical engineer Hiroshi Ashikaga, M.D., Ph.D., has developed a mathematical model to measure and digitally map the beat-sustaining electrical flow between heart cells.

The work, the scientists say, could form a blueprint for vastly more precise imaging tests that capture cell-to-cell communication and pinpoint the tiny clusters of cells at the epicenter of complex, life-threatening arrhythmias. Such imaging approaches, they add, would enable precision-targeted, minimally invasive treatments that eliminate rhythm-disrupting hotspots in the heart's electrical system.

The approach, described online March 4 in the Journal of the Royal Society Interface, is inspired by so-called information theory and built on the premise that cell-to-cell interaction follows a classic model of communication consisting of source, transmitter and receiver. Translating those cellular "conversations" into digital form -- a series of zeroes and ones that can be easily read and imaged by a computer -- can help spot breakdowns in communication that form the epicenters of dangerous rhythm disturbances.

"Successful arrhythmia treatment depends on correctly identifying the epicenter of the malfunction," Ashikaga says. "We cannot begin to develop such precision-targeted therapies without understanding the exact nature of the malfunction and its precise location. This new model is a first step toward doing so."

At the heart of the new model is the idea that heart muscle cells act as analog-to-digital converters, taking up information from their surroundings, converting or interpreting the information, and transmitting the message to neighboring cells. Ashikaga and colleagues say that capturing and quantifying information transmitted from cell to cell can help "catch" aberrant signals -- or communication breakdowns -- as they trigger electrical firestorms that cause the heart to beat abnormally and compromise its ability to pump blood.

The location of such communication glitches has been notoriously challenging to pinpoint with standard electrocardiograms, or EKGs, which provide limited information and are most helpful in diagnosing the type of arrhythmia rather than the exact cellular origin of the rhythm disturbance.

In their new model, the researchers mapped cellular information flow by creating computer representations of normal and abnormal heartbeats, ranging from simpler benign arrhythmias with well-defined epicenters to dangerous rhythms that arise in multiple hotspots. The scientists then "digitized" the electric flow by converting the electrical signals transmitted by cells into bits -- the zeroes and ones that are the basic units of information in computing and digital communications.

Next, they measured how much information was generated, transmitted and received during normal and abnormal heart rhythms and plotted the information onto a 2-D map to create an image of the arrhythmia.

The different types of arrhythmias generated markedly distinct spatial profiles. By contrast, regular EKG tracings of the same rhythm disturbances looked similar with a lot of overlapping features, an observation suggesting that quantifying and digitizing information flow inside the heart would far more reliably distinguish one form of arrhythmia from another.

The human heart is a muscle made up of 5 billion cells loosely linked together by so-called gap junctions that carry electrical signals from one cell to the next, a perfectly synchronized process that culminates in a heartbeat. At times, however, the propagation of the electrical signal fails due to an anatomic roadblock in the heart muscle -- such as scarring from a heart attack -- or because of chemical imbalances that lead to electric malfunction. Often, the misfiring cells can self-correct quickly, restoring the electric flow. But now and then, the aberrant signal can propagate into a cluster of neighboring cells and spark heart rhythm disturbances, some of them serious and some life-threatening. Two of those arrhythmias -- atrial fibrillation and ventricular fibrillation -- pose the gravest risk to health. Atrial fibrillation, which affects 6 million Americans, can lead to blood clot formation and stroke. It occurs when the heart's upper chambers start beating chaotically. Ventricular fibrillation, an often-lethal rhythm disturbance responsible for 150,000 cardiac arrests each year, occurs when the normal pumping activity of the heart's lower chambers degenerates into weak, quivering beats.

Current therapies for dangerous rhythms, including medication, catheter ablation or implanted defibrillators that shock the heart back into normal rhythm, are not always effective or have serious downsides. But pinpointing the origin of dangerous arrhythmias could lead to new therapies and improve the precision of surgical ablation, a minimally invasive procedure that uses heat energy to burn the hotspots that trigger aberrant rhythms. Ablation works well for simple rhythm disorders with a well-defined hotspot, but is far less effective for complex arrhythmias originating from multiple hotspots that cannot be precisely located with standard imaging techniques.
-end-
Other investigators involved in the research included José Aguilar-Rodríguez of the University of Zurich; Shai Gorsky of the University of Utah; Elizabeth Lusczek of the University of Minnesota; Flávia Maria Darcie Marquitti of the University of São Paulo, Brazil; Brian Thompson; Degang Wu of the Hong Kong University of Science and Technology; and Joshua Garland of the University of Colorado.

Media contacts:

Ekaterina Pesheva, epeshev1@jhmi.edu, (410) 502-9433

Helen Jones, hjones49@jhmi.edu, (410) 502-9422

Johns Hopkins Medicine

Related Atrial Fibrillation Articles:

Eating more protein could help ward off atrial fibrillation in women
Women who ate slightly more than the recommended daily amount of protein were significantly less likely to develop atrial fibrillation (AFib), a dangerous heart rhythm disorder that can lead to stroke and heart failure, when compared with those who consumed less protein, according to research being presented at the American College of Cardiology's Annual Scientific Session Together with World Congress of Cardiology (ACC.20/WCC).
Zebrafish teach researchers more about atrial fibrillation
Genetic research in zebrafish at the University of Copenhagen has surprised the researchers behind the study.
Personalized medicine for atrial fibrillation
The study, published in Europace, uses signals from implantable devices -- pacemakers and defibrillators -- to analyze electrical signals in the heart during episodes of atrial fibrillation.
Prescribing anticoagulants in the ED for atrial fibrillation increases long-term use by 30%
Patients prescribed anticoagulants after a diagnosis of atrial fibrillation in the emergency department are more likely to continue long-term use of medications to treat the condition, according to research published in CMAJ (Canadian Medical Association Journal).
Anticoagulant benefits for atrial fibrillation decrease with age
The net clinical benefit of anticoagulants for atrial fibrillation (AF) -- one of the most important causes of irregular heartbeats and a leading cause of stroke -- decreases with age, as the risk of death from other factors diminishes their benefit in older patients, according to a study led by researchers at UC San Francisco.
Research improves understanding of mechanism of atrial fibrillation
Mouse model studies show that noncoding DNA regions linked to atrial fibrillation risk can display long-range regulatory functions directed at Pitx2 gene and in this way predispose to the condition.
Medications used to treat atrial fibrillation may raise risk of falls
To prevent atrial fibrillation symptoms, health professionals may treat patients with medications to control their heart rate or rhythm.
Atrial fibrillation: New marker for atrial damage discovered
Atrial fibrillation is a common abnormal heart rhythm. It is treated either with medications or by applying heat or extreme cold to destroy small specific tissue areas in the atrium.
Former NFL players may face higher risk of atrial fibrillation
Former National Football League (NFL) players were nearly 6 times more likely to have atrial fibrillation (AF), a type of irregular heartbeat that can lead to stroke.
New technology improves atrial fibrillation detection after stroke
It's important to determine whether stroke patients also experience atrial fibrillation (Afib).
More Atrial Fibrillation News and Atrial Fibrillation Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.