"This book is incredibly complete and easy-to-understand for anybody. I certainly recommend it for patients who want to know more about atrial fibrillation than what they will learn from doctors...."

Pierre Jaïs, M.D. Professor of Cardiology, Haut-Lévêque Hospital, Bordeaux, France

"Dear Steve, I saw a patient this morning with your book [in hand] and highlights throughout. She loves it and finds it very useful to help her in dealing with atrial fibrillation."

Dr. Wilber Su Cavanaugh Heart Center, Phoenix, AZ

"Your book [Beat Your A-Fib] is the quintessential most important guide not only for the individual experiencing atrial fibrillation and his family, but also for primary physicians, and cardiologists."

Jane-Alexandra Krehbiel, nurse, blogger and author "Rational Preparedness: A Primer to Preparedness"


"Steve Ryan's summaries of the Boston A-Fib Symposium are terrific. Steve has the ability to synthesize and communicate accurately in clear and simple terms the essence of complex subjects. This is an exceptional skill and a great service to patients with atrial fibrillation."

Dr. Jeremy Ruskin of Mass. General Hospital and Harvard Medical School

"I love your [A-fib.com] website, Patti and Steve! An excellent resource for anybody seeking credible science on atrial fibrillation plus compelling real-life stories from others living with A-Fib. Congratulations…"

Carolyn Thomas, blogger and heart attack survivor; MyHeartSisters.org

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Terry Traver, former A-Fib patient

"If you want to do some research on AF go to A-Fib.com by Steve Ryan, this site was a big help to me, and helped me be free of AF."

Roy Salmon Patient, A-Fib Free; pacemakerclub.com, Sept. 2013

Implantable event monitors

A Primer: Ambulatory Heart Rhythm Monitors

A Primer: Ambulatory/Long-term Heart Rhythm Monitors

By Steve S. Ryan, PhD

ECG pads positioned

Source: www.afa.org.uk patient education brochure

If your arrhythmia is intermittent, your doctor may have you wear a mobile type of heart rhythm monitor to capture the electrical activity of your heart. As a general rule, in order to make a diagnosis of an arrhythmia, some form of electrocardiographic recording (i.e., EKG,) must be made at the time the arrhythmia is occurring.

If an arrhythmia becomes persistent and is present day-in and day-out, as often is the case for A-Fib, the diagnosis is quite easy with a routine EKG done in the physician’s office.

The challenge is when an arrhythmia occurs intermittently (on and off) or is self-limiting. In this case, an EKG performed in between A-Fib episodes can be completely normal. To circumvent this problem, one would go to the next level of evaluation with a long-term monitor.

Long-term monitors

Long-term monitors basically are EKG recorders that patients can take with them (ambulatory). They fall into two major categories: continuous recording (Holter) and intermittent recording (Event).

The Holter Monitor

Mortara H12+ Continuous 12-lead Holter recorder

Mortora H12+ Continuous 12-lead Holter recorder

A Holter Monitor (named after Dr. Norman Holter, go figure) records continuously the EKG of a patient, usually for 24 – 48 hours. More modern Holter units record onto digital flash memory devices. The data are uploaded into a computer where software analyzes the input, counting ECG complexes, calculating summary statistics such as average heart rate, minimum and maximum heart rate, and finding candidate areas in the recording worthy of further study.

The advantage of a Holter is that every single heartbeat during that day is recorded and can be analyzed. The disadvantage is that if an arrhythmia did not happen on that particular day, the Holter data would not be useful.

The Event Monitor

Cardionet wireless event monitor

Cardionet wireless event monitor

An Event Monitor, on the other hand, is a long-term monitor that can be used for up to 30 days or longer. The advantage is that the longer the recording period, the better chance of “catching” an intermittent arrhythmia. The disadvantage is that an Event Monitor must be activated by the patient and downloaded telephonically, a task that requires a certain amount of manual dexterity and may be difficult for some patients.

Some event monitors are patient activated when having an episode and save the last several minutes of data; others detect the irregular heart rate and automatically record the data.

Number of Electrodes

The number and position of electrodes varies by model, but most Holter monitors employ between three and eight, whereas the Event Monitors typically use two. Both the Holter and Event monitors record electrical signals from the heart via a series of electrodes attached to the chest. The Loop (event) monitor is not attached to the patient but is instead pressed to the chest by the patient when experiencing an A-Fib episode.

Implantable ambulatory event monitors

Medtronic Reveal® DX insertable cardiac monitor (ICM) continuously monitors

Medtronic Reveal® DX insertable cardiac monitor (ICM) continuously monitors

Implantable event monitors are also available for those instances where individuals experience such infrequent symptoms that extended monitoring is needed.

These devices are inserted just under the skin in the chest area during an outpatient surgical procedure. The device may remain implanted for over one year.

Implantable loop recorders have the ability to record events either automatically (auto activated) or by manual activation (self-activated).

Real Time Remote Cardiac Recording

CardioNet MCOTos Event wireless event monitor

CardioNet MCOTos Event wireless event monitor

An example of the newer monitoring technologies is the Ambulatory Cardiac Telemetry (ACT), a wireless cardiac telemetry system.  This event monitor is designed for remote arrhythmia monitoring in any location.

A small transmitter worn on the patient sends the ECG data to a portable handheld device where it is analyzed.  If an arrhythmia is identified, the data is automatically transmitted to a Monitoring Center for immediate review. Integrated into a state-of-the-art mobile phone, the ACT provides next generation cardiac arrhythmia monitoring. What’s interesting is the transmitter is a dongle type device worn around the neck with leads placed on the chest. You carry or have available what, in essence, is a mobile phone (it’s actually more than a phone). It is small and not cumbersome.

No patient input is required. Data collected from the monitors is transmitted to the monitoring center via a cellular network, the internet, or over the phone (based on model). Data from the monitors is not intended to be used directly by the patient but rather by the monitoring center and your cardiologist.

Next-Generation: the ‘Smart Band-Aid’ Zio Patch

Steve wearing a Zio Patch

Steve wearing a Zio Patch

The ‘Smart Band-Aid’ provides the next-generation ambulatory cardiac monitoring service with beat-to-beat, real time analysis, automatic arrhythmia detection and wireless ECG transmission.

The sensors in the Band-Aid can be modified to monitor a number of different tasks as they can also provide a comprehensive suite of post-symptom, looping, and auto trigger event monitors as part of its turn-key cardiac event monitoring service.

Additional Reading

For a scholarly review of medical heart rate monitors, see: New Methodologies in Arrhythmia Monitoring by Anderson & Donnelly.

References for this article

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Return to Index of Articles: Diagnostic Testing

Last updated: Thursday, September 3, 2015


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