2017 Article Identifies Rotating Waves during Atrial Fibrillation

 

Atrial Flutter pic
Atrial Fibrillation
Image: webmd.com

Stanford University professor Dr. Sanjiv M. Narayan is an expert in atrial fibrillation (AF), a medical condition defined by an irregular and often accelerated heartbeat. One of Dr. Sanjiv Narayan’s recent studies on the topic appeared in the June 2017 issue of the Journal of Cardiovascular Electrophysiology.

Entitled “Two Independent Mapping Techniques Identify Rotational Activity Patterns at Sites of Local Termination during Persistent Atrial Fibrillation,” the study addressed uncertainties in the general medical understanding of AF that arise as the result of inconsistent mapping techniques. It accomplished this by comparing two independent AF mapping techniques that measured results in the same patients.

The first study of its kind to use more than one AF mapping method, it identified stable rotational activation at specific sites in the heart that drove AF for multiple cycles. Both mapping methods confirmed these results. Researchers developed a new computer program to chart their findings and subsequently released this program for free on the Internet.

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Atrial Fibrillation Study Builds on Mapping of Rotors, Focal Drivers

Sanjiv Narayan Abbott pic
Sanjiv Narayan

A professor of cardiovascular medicine at Stanford University, Dr. Sanjiv M. Narayan is working to develop the Stanford Arrhythmia Center, which focuses on creating innovative bioengineering-based treatments for complex heart rhythm disorders. As a bioengineer, Sanjiv Narayan also applies his background in neural networks, machine learning, and artificial intelligence to the field of cardiology at the Computational Arrhythmia Research Laboratory.

After extensive work that resulted in discovery of the role of focal drivers and rotors in heart fibrillation, Dr. Narayan coauthored a paper on what independent mapping techniques showed about the presence of rotational activation. The paper was published in the January 29, 2018, issue of the Journal of Cardiovascular Electrophysiology.

The authors of the paper worked with the goal of finding out how, during the process of ablation, atrial fibrillation terminates close to the pulmonary veins prior to pulmonary vein isolation. This research represents the first full study of that phenomenon, as well as the first study of how patients with pulmonary vein reconnection can be free of arrhythmias.

The study involved patients with atrial fibrillation who had been scheduled for ablation. The researchers examined specific electrograms from these patients using two distinct mapping methods. In all patients studied, ablation at locations close to the pulmonary veins resulted in a termination of atrial fibrillation before the isolation of the pulmonary veins.

The researchers concluded that surgeons may be able to use these mapping techniques to create pulmonary vein lesion groups and lessen the occurrence of atrial fibrillation.

Studying Atrial Fibrillation Terminated by Local Ablation

Atrial Flutter pic
Atrial Fibrillation
Image: webmd.com

An experienced researcher specializing in atrial fibrillation, Dr. Sanjiv M. Narayan, professor of medicine at Stanford University, is responsible for developing innovative assessment tools for diagnosing heart arrhythmia conditions. Dr. Sanjiv M. Narayan’s research recently focused on the mechanisms of and relationship between localized ablation and persistent atrial fibrillation termination.

As part of a clinical trial, researchers hypothesized that local ablation sites where AF persistently terminates have certain indicators that can be analyzed through activation mapping techniques. To test this theory, they closely studied activation patterns that occurred solely in instances of AF termination via ablation.

After examining the results, the research team found patterns of either rotational or focal activity when mapping termination sites. Computer simulations also revealed rotational activation sequences, but the sequences were found to have increased sensitivity to activation timing, especially in areas where slow conduction was a factor. Based on these observations, the researchers stated that many currently used tools to map AF may not detect important regions, including sites of termination, and further studies should compare mapping approaches to guide ablation.

Basics of Atrial Fibrillation

 

Atrial Fibrillation pic
Atrial Fibrillation
Image: webmd.com

Sanjiv M. Narayan has served as a professor of medicine at Stanford University since 2014. Sanjiv M. Narayan has published extensively on topics related to atrial fibrillation, an ongoing heart irregularity, with over two hundred articles and book chapters. His laboratory works to define mechanistic networks that can cause this condition, and his recent research focuses on ablation treatment focused at small ‘driver’ or ‘rotor’ regions that sustain the disorganization of atrial fibrillation.

Atrial fibrillation is a form of irregular and rapid heart rate in which the heart’s upper chambers stop synchronizing with the lower chambers. Beats can be chaotic and irregular, and often manifest as heart palpitations, shortness of breath, and generalized weakness. Individuals with atrial fibrillation may deal with the condition constantly, or have occasional episodes. While not life-threatening, it can require emergency treatment in certain circumstances.

Atrial fibrillation can also cause further complications. The irregularities in the heartbeat can lead to the formation of blood clots inside the heart, which can migrate around the body and block blood flow. This can cause a stroke if the blood clot lodges in the brain. Heart failure can occur if the irregularities weaken or exhaust the heart, causing the heart to circulate insufficient blood to serve the body.

Atrial Fibrillation Study on Ablation and Pulmonary Veins Isolation

 

Atrial Fibrillation pic
Atrial Fibrillation
Image: webmd.com

A respected California cardiologist, Dr. Sanjiv M. Narayan was responsible for developing new atrial fibrillation treatments that were acquired by Abbott Laboratories. Presently a Stanford University professor focused on establishing an arrhythmia center, Dr. Sanjiv M. Narayan has coauthored papers such as “Independent mapping methods reveal rotational activation near pulmonary veins where atrial fibrillation terminates before pulmonary vein isolation” (Journal of Cardiovascular Electrophysiology, 2018).

Atrial fibrillation involves the upper chambers of the heart beating irregularly, which disrupts the effective movement of blood into the ventricles. Blood clot is a common cause, and stroke can result in cases where the clot breaks off and gets stuck in the artery that leads to the brain. The procedure known as AF ablation involves carefully destroying or scarring targeted heart tissue in a way that disrupts the defective electrical signals that cause arrhythmia.

The study focused on exploring mechanisms through which, prior to pulmonary veins (PV) isolation, atrial fibrillation (AF) can be terminated in the vicinity of the PV during ablation. The study included 22 patients and found that localized rotational (‘whirlpools’) or focal activity was present at the site near the Pulmonary Veins in each case where AF was terminated by ablation. This may explain the benefit of PV ablation in AF. Through mapping such sites, PV lesion sets can potentially be tailored for each patient, and sites outside the PVs can be targeted.

A Brief Overview of Atrial Fibrillation Symptoms and Treatments

Sanjiv Narayan Abbott pic
Sanjiv Narayan Abbott

An accomplished physician and medical innovator, Dr. Sanjiv Narayan developed a novel atrial fibrillation (AFib) therapy that was acquired by Abbott Laboratories. By selling his technology to Abbott, Dr. Sanjiv Narayan advanced his goal to make improved therapies more widely available to those with AFib, a condition he has studied and treated throughout his career.

Characterized by a rapid and irregular heart rhythm, AFib is a relatively common arrhythmia disorder that causes symptoms ranging from chest pain and fatigue to dizziness and confusion. In addition to experiencing these bothersome symptoms, AFib patients are at a higher risk for stroke, so physicians often prescribe a blood-thinning medication along with rate-control and anti-arrhythmic medications as part of their treatment plan.

Other treatments include both nonsurgical and surgical procedures, such as electrical cardioversion and cardio ablation. Currently, many physicians and medical companies, including Abbott Electrophysiology, are working to improve upon these treatments and introduce new therapies that could potentially lead to better outcomes for AFib patients.