Detecting Atrial Fibrillation Using Video Technology in Mobile Devices

After more than a decade on faculty at the University of California, San Diego, Sanjiv M. Narayan, MD, Ph.D. became a professor of medicine at Stanford University. A cardiologist, Dr. Sanjiv Narayan focuses on the diagnosis and treatment of atrial fibrillation.

Wearable and mobile devices may play a bigger role in the diagnosis of arrhythmias like atrial fibrillation. A recent study showed the efficacy of using smartphones to monitor for atrial fibrillation. The researchers used videoplethysmography software on smartphones that can use the selfie video function to identify irregular pulse rates. This sort of technology has become more important in recent months with telemedicine becoming more prevalent due to the coronavirus pandemic.

The video technology makes it possible to intermittently monitor for atrial fibrillation in a long-term fashion without the need for wearable devices. The software detects very subtle changes in skin color of the face during heartbeats to determine pulse rate. When compared to a standard ECG patch, the mean difference in pulse and heart rate between the technologies was only 0.3 beats per minute, indicating the efficacy of using smartphones as a contactless monitoring device.

Atrial Fibrillation Treatments at the Stanford Arrhythmia Center

Board certified in clinical cardiac electrophysiology, Dr. Sanjiv M. Narayan teaches medicine, cardiology, and bioengineering as a professor at Stanford University. Dr. Sanjiv Narayan also co-founded the Stanford Arrhythmia Center, which develops world-class therapies for heart-rhythm disorders.

Disorders treated at the center include atrial fibrillation (AFib), a condition characterized by an abnormal heart rhythm that causes fatigue and heart palpitations. The center’s staff and specialists provide comprehensive care for patients with AFib using the least invasive techniques possible. Patient treatment begins with two essential steps: stroke assessment and management, followed by the restoration of normal heart rhythm and rate.

Every patient at the center receives a care plan based on a thorough evaluation of his or her risk for a stroke. The plan outlines the necessary medications and advanced treatments to manage strokes. The second step focuses on restoring the heart’s normal rhythm and rate and relieving associated symptoms. While the center’s care staff prioritize finding the most minimally invasive approaches, treatments can range from medication to lifestyle changes. Furthermore, doctors may consider ways to alleviate related heart disorders.

If minimally invasive approaches fail to correct AFib symptoms, the center offers a variety of procedures carried out by skilled doctors and surgeons. Doctors collaborate with patients to determine the best possible approach, which may include electrical cardioversion, catheter ablation, or maze surgery.

Studying Localized Drivers in Persistent Atrial Fibrillation

Dr. Sanjiv M. Narayan helped spearhead medical results that led to a technology acquired by Abbott Laboratories. Currently a Stanford University professor of medicine, Dr. Sanjiv M. Narayan has been at the forefront of research that examines the mechanisms governing persistent atrial fibrillation.

Previously, the drivers of persistent atrial fibrillation have not been easily traceable or understood. For a recent clinical trial, the research team operated on the hypothesis that putative AF drivers may have a dynamic synergy with disorganized zones across small time frames. They examined these types of interactions across long periods of time with an emphasis on areas where mapping methods were able to indicate regions of termination via ablation. 

Among the 55 patients who participated in the study, AF termination points via ablation had organized activation that varied across different time points when interacting with fibrillatory waves and/or organized zones, but showed more consistent recurrence in conserved spatial areas. Researchers concluded these results show that mapping the atrium in each patient undergoing AF ablation may help to understand the interaction between important sites (AF drivers) and hence guide ablation. These tools should be integrated with other AF mapping methods.

Study Correlates Atrial Fibrillation and Long-Term Stroke Risk

Dr. Sanjiv M. Narayan is a respected presence in the atrial fibrillation (AF) research community who has developed novel mapping techniques and serves as Stanford University professor. Focused on developments in his field, Dr. Sanjiv Narayan stays informed on the latest studies on AF diagnosis and treatment approaches. 

As noted on the Harvard University health website, a recent study published by JAMA Cardiology (May 2018) brought focus to the risks of stroke presented by atrial fibrillation episodes, which involve an irregular and chaotic heart rhythm. With such episodes lasting anywhere from minutes to weeks, the condition is described as encouraging formation of blood clots within the heart. 

The study involved 2,000 paroxysmal (intermittent) AF patients, who were not on anti-clotting drugs, wearing a skin patch that provided continuous heart rate monitoring over a two-week period. Over the next five years, participants' stroke incidences were monitored, with a core finding being that atrial fibrillation episodes lasting more than 11 percent of the total time were associated with increased stroke incidence three times that of the baseline.

The research suggests that even intermittent AF bouts can have a significant impact in elevating the risk of stroke. Further studies are needed to determine better ways of evaluating specific prevention strategies that minimize the stroke risk burden.

Dipole Density Mapping Validated in Atrial Fibrillation Cases

Dr. Sanjiv M. Narayan, a respected presence in the Southern and Northern California cardiology sphere, developed pioneering atrial fibrillation (AF) care techniques which are now supported other studies. Sanjiv Narayan’s research findings have been validated in the 2017 paper "Dipole Density Mapping of Atrial Fibrillation” (European Heart Journal).

With primary researcher Cambridge University professor Andrew Grace serving on the Acutus Medical Scientific Advisory Board, the study involved a new Acutus Medical mapping system that addresses the complexity of AF patient-specific arrhythmia. Unfortunately, the present care standard for persistent AF is the same as for paroxysmal AF, although the outcomes are significantly inferior for patients with the persistent form of the condition. 

An innovative diagnostic tool, the AcQMap System enables the cardiac tissues that cause arrhythmias to be located and precisely targeted, in the process minimizing the need for redundant therapies. The early clinical results reveal that this approach elevates the accuracy of left atrial reconstruction, without elevated patient risk, through successfully mapping unstable and stable atrial arrhythmias. 

As described by Dr. Grace, the AcQMap’s advanced performance is likely to present an improved pathway for treating persistent AF, as compared with 3D voltage-based mapping systems.

Study on Localized Atrial Fibrillation (AF) That Ends Persistent AF

A professor of medicine at Stanford University, Dr. Sanjiv M. Narayan has led basic human heart rhythm disorder research in areas that were little studied. Extensively published in his field, Dr. Sanjiv M. Narayan coauthored “Identification and Characterization of Sites Where Persistent Atrial Fibrillation Is Terminated by Localized Ablation” (Circulation Arrhythmia Electrophysiology, 2018).

With atrial fibrillation (AF) characterized by irregularity of heartbeat and presenting a danger of blood-clot-related stroke, the study sought to increase knowledge of how persistent AF terminates when localized ablation is undertaken. Cardiac ablation involves the elimination or scarring of the heart tissue responsible for allowing incorrect electrical signals that activate the heart muscles in a way that results in abnormal heart rhythm.

A study hypothesis was that those sites at which localized ablation eliminates persistent AF have characteristics that can be identified through activation mapping when AF occurs. With 57 patients taking part in the study, complex analysis was undertaken that revealed repetitive rotational or focal activity patterns occurring at all sites in which AF termination occurred. Not all methods were equally effective at identifying these sites. The mechanism through which local ablation has this effect is described as needing further research.

New Gene Therapy Approach to Treating Atrial Fibrillation

An accomplished cardiologist, Dr. Sanjiv M. Narayan has been granted National Institutes of Health funding to undertake basic research in understudied areas of human heart rhythm disorders (arrhythmia). Technology focused, Dr. Sanjiv M. Narayan was successful in developing a pioneering system that addressed patient atrial-fibrillation-care needs. 

Atrial fibrillation (AF) is the most prevalent type of arrhythmia. Its treatment focuses on restoring the normal rhythm of the heart, and encompasses anticoagulant drugs that not all patients respond to as well as electric shocks that require patient hospitalization. 

A recent study at the Leiden University Medical Centre in the Netherlands examined the potential use of genetically modified cells in enabling the heart to terminate AF on its own.

Employing a gene painting process, the right atrium of hearts in adult rats were genetically modified such that they expressed light-sensitive ion channels. Shining a light on the atrium for one second resulted in an opening of these light-sensitive ion channels in rats with induced atrial fibrillation. This resulted in a restoration of normal heart rhythm and termination of the atrial fibrillation.

As described by the researchers, this technique has the potential to be used for atrial fibrillation patients, in tandem with an implantable LED device, such that the heart’s normal rhythm could be maintained in a continuous and pain-free manner.

Defining and Identifying Atrial Fibrillation

Sanjiv Narayan, a medical professional and entrepreneur, is co-founder of Topera, Inc., which was recently acquired by Abbott Laboratories. One of the medical conditions that Sanjiv Narayan focuses on is atrial fibrillation.

Atrial fibrillation, commonly called AF, refers to an irregular or rapid heart rate (arrhythmia). This condition, which feels like a quivering or trembling heart, increases people’s chances of heart failure, stroke, and other complications.

AF results when the two upper chambers of the heart, called the atria, have dangerously irregular beats that don’t harmonize with the beats of the two lower chambers of the heart, called the ventricles. Symptoms of AF include shortness of breath, palpitations, and weakness.

For some patients, AF is sporadic, and for others, it is constant. Since AF is a serious condition, it merits treatment by a medical professional as it indicates that there may be underlying problems. It is estimated that up to 15% and 20% of stroke patients may have AF - which is often undiagnosed. One important research area is to determine if treating AF can reduce the risk for stroke.