News | EP Lab | July 27, 2017

Ohio State Researchers Prove Human Heart's 'Battery' Has Multiple Backups

Better understanding of intranodal pacemakers may help cardiologists more accurately determine who needs a pacemaker

Ohio State Researchers Prove Human Heart's 'Battery' Has Multiple Backups

July 27, 2017 — There is good news when it comes to the heart’s sinoatrial node (SAN), the body’s natural pacemaker. Scientists at The Ohio State University Wexner Medical Center have shown the human SAN is hardwired with a backup system — three diverse regions of pacemakers acting as batteries and up to five conduction pathways that act as wires to connect the signal to the atria. This built-in redundancy maintains consistent heart rhythm, even under trying conditions.

The research is published online by the journal Science Translational Medicine.

Like a battery, the SAN generates electrical impulses to initiate heartbeats. Until now, scientists didn’t know for sure how the SAN protected the heart’s rhythm and how the system failed.

“It’s been challenging because our human SAN differs greatly from well-studied animal models, and clinical electrode recordings only capture what’s on the surface,” said Vadim Fedorov, an associate professor in Ohio State’s Department of Physiology and Cell Biology.

So Fedorov and his team applied optical mapping, 3-D structural imaging and molecular mapping to 21 explanted human hearts to define the internal function of the SAN. The hearts, which are not viable for human transplant, were donated by heart transplant recipients and Lifeline of Ohio.  

To resuscitate the hearts, researchers placed them in a glass chamber filled with an oxygenated solution at body temperature and perfused the coronary arteries with warm, oxygenated solution that simulates blood flow, allowing the SAN to beat again with the same rhythm as when it was inside the body for at least 12 hours.

Then the chamber with live heart tissue is surrounded by four highly-sensitive infrared cameras, and a fluorescent dye is injected. This dye can visualize spontaneous electrical activity moving within the human SAN in 3-D.

“We observed that all three intranodal pacemakers are used, depending on the heart’s needs at rest, or during normal or high exertion,” Fedorov said.

To study how the SAN functions under stress, Fedorov’s team applied adenosine, a heart rhythm regulator that is overproduced when there is heart failure and inadequate blood supply.

“The central pacemaker was most affected, as it is highly sensitive to adenosine. The head and tail pacemakers were able to maintain a slower rhythm and prevent complete cardiac arrest. We saw similar shifts in the preferred conduction pathways,” Fedorov said. Total cardiac arrest occurs only when all pacemakers or conduction pathways fail, whether due to disease or age.”

When there is a problem with SAN pacing or conduction, doctors implant an electronic pacemaker to prevent cardiac arrest. Approximately 225,000 Americans get a pacemaker every year, according to the World Society of Arrhythmia.

“Patients are at high risk of cardiac arrest if the SAN gets down to one pacemaker, or one conduction pathway,” Fedorov said. “Knowing this, our next quest is to work with electrophysiologists to more precisely identify who needs a pacemaker implant, and who still has backups and can get along without one.”

Clinicians are excited by this discovery.

“It’s groundbreaking. This is the first step in explaining why the SAN can be ‘sluggish’ for years before a total failure, allowing the clinician to detect the problem before a catastrophic event,” said Raul Weiss, M.D., a cardiologist and clinical researcher at Ohio State.

“I think this work can fundamentally change the way we diagnose disease of the heart’s natural pacemaker,” said John Hummel, M.D., a cardiologist and clinical researcher at Ohio State. “In some patients, it can be incredibly challenging, and these insights may allow us to diagnose those challenging patients more effectively.”

Because a pacemaker is merely a crutch and cannot fix the underlying problem, Fedorov’s team is also seeking out ways to improve or restore the impaired portions of the SAN. Their hope is that someday, pacemaker implants could be obsolete.

This research was funded by the National Institutes of Health, the American Heart Association, the C.R. Webb Fund in Cardiovascular Research and the TriFit Challenge Discovery Fund.

Other Ohio State researchers include: Ning Li, Brian Hansen, Thomas Csepe, Anthony Ignozzi, Lidiya Sul, Stanislav Zakharkin, Anuradha Kalyanasundaram, Jonathan Davis, Brandon Biesiadecki, Ahmet Kilic, Paul Janssen and Peter Mohler.

For more information: www.stm.sciencemag.org

Related Content

Societies Publish New Guidance for Treatment of Slow, Irregular Heartbeats
News | EP Lab | November 09, 2018
The American College of Cardiology (ACC), the American Heart Association (AHA) and the Heart Rhythm Society (HRS)...
A view of the EPD Solutions catheter ablation system image guidance. It displays the catheter within a pre-acquired 3D segmented CT image. The D700 system provides a real-time lesion assessment tool that predicts transmurality and permanency of lesions, pre- and immediately post-ablation.

A view of the EPD Solutions catheter ablation system image guidance. It displays the catheter within a pre-acquired 3D segmented CT image. The D700 system provides a real-time lesion assessment tool that predicts transmurality and permanency of lesions, pre- and immediately post-ablation.

News | EP Lab | June 05, 2018
June 5, 2018 — Philips Healthcare has signed an agreement to acquire EPD Solutions, a provider of image-guidance in c
A recent study shows the Baylis NRG radiofrequency (RF) Transseptal puncture catheter has a lower incidence of embolism in EP cases.
News | EP Lab | May 21, 2018
May 21, 2018 — A recent study published in Heart and Vessels has found that the use of the Baylis Medical NR
Myocarditis is an Under-recognized Etiology of Symptomatic Premature Ventricular Arrhythmia (PVCs). #HRS #HRS2018
News | EP Lab | May 18, 2018
May 18, 2018 — A significant number of patients with symptomatic premature ventricular contractions (PVCs) have under
Novel Antibiotics Can Help Lower EP Device Infection Rates. Pictured here is an ICD. Implantation of pacemakers, ICDs and the related cardiac leads opens patients to infection risk.

Implantation of pacemakers, ICDs and the related cardiac leads opens patients to infection risk.

News | EP Lab | May 17, 2018
May 10, 2018 – A new study is the first to test the clinical effectiveness of incremental peri-operative antibiotics
The Apple Watch Series 2, Samsung Galaxy Gear S3 and the Fitbit Charge 2 were all able to properly diagnose the very rapid heart beats involved in  paroxysmal supraventricular tachycardia (PSVT). #HRS2018

The Apple Watch Series 2, Samsung Galaxy Gear S3 and the Fitbit Charge 2 were all able to properly diagnose the very rapid heart beats involved in  paroxysmal supraventricular tachycardia (PSVT).  

News | EP Lab | May 16, 2018
May 16, 2018 — A new study is the first to validate the accuracy of wrist-worn wearable devices in measuring induced
LivaNova Completes Sale of Cardiac Rhythm Management (CRM - electrophysiology) Business to MicroPort Scientific
News | EP Lab | April 30, 2018
April 30, 2018 — LivaNova announced it completed the sale of its cardiac rhythm management (CRM) business to MicroPor
LivaNova Enters Binding Letter of Intent to Sell Cardiac Rhythm Management Business
News | EP Lab | January 26, 2018
January 26, 2018 — LivaNova PLC and MicroPort Scientific Corp.
Societies Detail Treatment for Patients With Ventricular Arrhythmias
News | EP Lab | October 30, 2017
The American College of Cardiology, along with the American Heart Association and the Heart Rhythm Society, published...
Overlay Init