Examining Ablation in Concert with PVI for Treating AF

An accomplished educator and researcher, Dr. Sanjiv M. Narayan serves as a professor of medicine and the director of the Stanford Arrhythmia Center. Dr. Sanjiv Narayan has studied numerous aspects of atrial fibrillation (AF), including ablation of AF drivers and its clinical implications. 

Pulmonary vein isolation, or PVI, is a procedure used to stop abnormal electrical signals in the heart that cause atrial fibrillation. PVI as a treatment for AF has been met with less-than-optimal outcomes, however, and the impact of adding lesion sets--additional surgical treatments for AF--has yet to be adequately explored. 

Some recent studies suggest that AF driver ablation, through which doctors intentionally scar tissues by sending irregular electric signals to the heart, may be a preferable treatment option to couple with PVI, but others suggest otherwise. In an effort to gain a clearer perspective, Dr. Narayan and a team of researchers conducted a comprehensive meta-analysis of all the literature on the subject.

The research team found that supplementing PVI treatment with AF driver ablation may be an option to improve patient outcomes, with several studies supporting this approach using several techniques. They suggest randomized clinical trials conducted at different research centers to study the treatment in further detail.

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.

Dipole Density Mapping Study Mirrors Work of Dr. Sanjiv Narayan

A leading researcher in atrial fibrillation (AF), Dr. Sanjiv M. Narayan operates as a professor of medicine and bioengineering at Stanford University, as well as director of the school’s electrophysiology research and atrial fibrillation programs. In 2017, a research group from Cambridge University published the study “Dipole Density Mapping of Atrial Fibrillation,” which reproduced many of the same results Dr. Sanjiv Narayan and his team had discovered in the 2012 paper, “Treatment of Atrial Fibrillation By the Ablation of Localized Sources.”

First published in the medical text European Heart Journal, the team responsible for the 2017 paper was led by Professor Andrew Grace, PhD, of Cambridge University. The researchers contend that a process known as dipole density mapping provides scientists with a more accurate representation of complex arrhythmias than the standard electrocardiogram. This is because the electrocardiogram is a voltage-based mapping system that can obscure complex patterns in arrhythmia by blending activities the dipole density mapping method is capable of delineating. Dipole density mapping delineates by measuring local charge-sources within the interior surface of the heart chamber being tested.

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.

Cartofinder Potential Validated in Atrial Fibrillation Mapping

A respected presence in atrial fibrillation (AF) research, Dr. Sanjiv M. Narayan guided a technology development startup that was acquired by Abbott Laboratories. Presently a Stanford University professor, Dr. Sanjiv M. Narayan’s research showed that AF could be mapped to show localized sources. Others now supporting this concept include companies and products such as Acutus, CardioNXT, and Cartofinder.

Cartofinder software was employed in a study of activation-based mapping techniques used in detecting the presence of AF-linked rotors, or “patient-specific recurrent rotational organized activity.” 

With Boston Scientific’s Constellation 64-electrode basket catheter employed among patients with AF, Biosense-Webster’s Cartofinder software was used to analyze results offline. In addition, the latter company’s CARTO 3-D electroanatomic mapping system was utilized. 

The results emphasized the attractiveness, on many levels, of rotor identification (AF RAP) that has been integrated within conventional 3-D mapping systems. This includes immediate accessibility of voltage information in evaluating potential scar or fibrosis areas. It also allows the quick identification of anatomic structures prone to sustain rotors and could potentially enable improved RFA targeting. 

One conclusion is that further validation testing of the algorithms in use, spanning the full range of AF types, is necessary in ensuring that intracardiac signals are correctly analyzed.

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.

Getting the Most Out of Time in the Pool

Sanjiv M. Narayan has, for nearly three decades, been part of the medical field, building an extensive body of research regarding heart rhythm irregularities. During his spare time, Sanjiv Narayan enjoys staying physically fit and considers swimming and skateboarding among his favorite athletic activities.

Swimming can be an intensive workout, but getting what one wants out of a swim can be challenging. With a little preparation, however, swimmers can meet their fitness goals and not get bored.

Different strokes train different muscle groups and stress different parts of the body. The breaststroke, for instance, improves the leg muscles, while crawl is great for stamina and cardiovascular health. Those looking for a solid core can use the butterfly, while those who want better posture can try the breaststroke.

Those who really want to focus in on individual trouble areas can consider pool toys and other assistive devices. A hand paddle or float can help isolate individual body parts. Similarly, a swim parachute can create drag, improving both speed and stamina. By using these devices, swimmers can get the exact workout their bodies need.

Electrophysiology - What to Expect

Dr. Sanjiv M. Narayan serves as director of the atrial fibrillation and electrophysiology research programs at Stanford University. Dr. Sanjiv Narayan has shared his work through such publications as Circulation, Journal of the American College of Cardiology, Journal of Cardiovascular Electrophysiology which from 2002 to 2017 have published his team's findings on the mapping of irregular heart rhythms.

Electrophysiology (EP) is a category of testing that evaluates the electrical activity of the heart and the patterns that it follows. Often used to evaluate the source of an arrhythmia, or regular heartbeat, it can assist in the development of a course of treatment.

The patient visits an EP or catheterization (cath) lab, where he or she receives a sedative and local anesthetic. The doctor will then make a small incision in the groin, arm, or neck, to thread a small tube known as a sheath into a particular vein or artery. This sheath contains a series of specialized catheters, which the physician will guide toward the heart.

Once the catheters are in place, the physician will send electrical signals into the heart to safely reproduce the irregular heartbeat. The catheters will record the heartbeat in a way that maps the arrhythmia. This allows the physician to identify the source of the abnormality.

The process usually takes between one and four hours. When it is finished, the doctor will remove the catheters. Recovery time, which includes pressure and elevation of the surgical site, usually lasts for one to three hours.

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.

AHA Study Looks at Vegetable Intake Impact on Heart Disease Risk

An experienced cardiologist and educator, Dr. Sanjiv M. Narayan specializes in researching and treating heart arrhythmia. A professor of medicine at Stanford University, Dr. Sanjiv Narayan belongs to the American Heart Association. 

A recent study in the Journal of the American Heart Association showed that women who eat more vegetables have a decreased thickness in their artery walls. The foods used in the study were broccoli, cabbage, cauliflower, and other cruciferous vegetables. 

Researchers found that arterial wall thickness decreased by 0.05 millimeters in those who had an increased intake of cruciferous vegetables. Each 0.1-millimeter decrease in thickness can equate to a 10- to 18-percent smaller risk of a stroke or heart attack.

Though the study shows promise, researchers were quick to say that, without further research, they can’t confirm a direct relationship between the increased vegetable intake and the arterial wall thickness.

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.

Study Links Sleep-Disordered Breathing and Heart Failure Risks

Dr. Sanjiv M. Narayan is a pioneering cardiologist who, in his career, has developed novel strategies for treating atrial fibrillation and improving patient outcomes. Among Dr. Sanjiv M. Narayan’s other areas of interest is sleep-disordered breathing, which is linked to conditions such as the stiffening of arterial walls and the increased risk of heart failure. 

The results of a recent study by researchers at Fukushima Medical University, published in ESC Heart Failure, a journal of the European Society of Cardiology, reinforced this link. The study showed a positive correlation between the severity of sleep-disordered breathing and arterial stiffness. 

The findings suggest that treatments of obstructive sleep apnea through the use of continuous positive airway pressure (CPAP) devices and other technologies may have a positive impact on patient prognosis. 

As study coauthor Dr. Akiomi Yoshihisa described it, the effective use of CPAP may extend beyond the hypertension that it is currently confirmed to address and enable recovery among patients at risk of preserved ejection-fraction-linked heart failure.