App. of AI in Cardiovascular Medicine

A cardiologist and professor of medicine at Stanford University, Sanjiv M. Narayan, MD, is highly recognized in San Diego for treating numerous veterans with life-threatening heart rhythm disorders. Dr. Sanjiv Narayan attended the University of Birmingham, where he received his MD and PhD. He also takes an interest in various clinical interests, such as machine learning and AI.

Machine learning (ML)-based artificial intelligence systems are revolutionizing cardiovascular medicine. These systems have to offer added precision and timely delivery of crucial care to mitigate the future emergence of debilitating and potentially lethal heart problems. For the most part, ML-embedded AI is trained with ECG data to familiarize underlying algorithms with the concepts of diagnosis and prognosis of cardiovascular abnormalities. With this knowledge, AIs can streamline workflow in clinical settings by helping clinicians perform some tasks that traditionally require the skills of a cardiovascular expert.

To comprehend how useful AIs can be in the field of cardiovascular settings, consider how Mayo Clinic scientists have successfully automated the cardiovascular examination of patients. Mayo Clinic uses AI systems to detect warning signs of dangerous heart problems through ECGs. The Mayo Clinic database has over seven million ECG records. The art of diagnosis was taught to machines by feeding the systems with data. Of course, each patient's ID was removed before relaying the data to computer systems for training to avoid violation of privacy.

The ML-embedded AI systems demonstrated accuracy in detecting weak heart pumps from ECG analysis with the data. Weak heart pumps are warning signs of heart failure in the future. These predictions also come at a lower cost than what would be required if human experts made the diagnosis. The systems also boast faster results, as each evaluation takes just a couple of seconds.

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.

T Wave Alternans Can Help Detect Potential Heart Defects

Board-certified in Clinical Cardiac Electrophysiology, Dr Sanjiv Narayan serves as the professor of cardiovascular medicine at the Stanford University Medical Center. Sanjiv Narayan, PhD, has written several medical papers, including the role of alternating repolarization in causing rhythm problems.

Repolarization changes can cause arrhythmias. This was previously part of the surface electrocardiogram phenomenon of "T wave (repolarization) alternans" and is now increasingly noticed in the atrium. This is detectable using clinical tools but also several research tools. These are being explored to better understand the heart rhythm problem, and also to improve therapy of patients.

Ventricular arrhythmia can cause asymptomatic heart failure, leading to death without prior notice. In some cases, however, ventricular arrhythmia may present with less potent lethal complications such as ventricular fibrillation and ventricular tachycardia. Current treatments for ventricular arrhythmia involve device therapy and ablation. These can be effective, but it is difficult to identify which patients may benefit from each form of therapy.

Can Heart Attacks Trigger Arrhythmia?

A member of the Heart Rhythm Society, Dr. Sanjiv Narayan is a professor of cardiovascular medicine at Stanford University. Sanjiv M Narayan is dedicated to helping cardiologists develop cutting-edge therapies for treating patients with arrhythmia.

A condition that occurs when electrical impulses in the heart become irregular, arrhythmia results in the heart beating too slow, too fast, or without a normal pattern. Symptoms of arrhythmia may include sweating, chest pain, dizziness, or shortness of breath. Certain medical conditions, such as diabetes, sleep apnea, high blood pressure, or thyroid disease can increase a person's chance of having an arrhythmia.

At the University of California, a group of researchers has also investigated the potential genetic link between heart attacks and arrhythmia, as these two medical issues only occur in a subset of the population. During the research study, the actions of mutated versions of a gene called 9p21 were investigated. It was discovered that when a heart attack occurs, the mutated gene activates a signaling protein called JNK that performs a key role in triggering arrhythmia. JNK sends signals that break the connection between heart cells, thus causing the heart to beat irregularly

Acutus Medical Gains $170M Funding for Its Intracardiac Mapping System

Human Heart Model Photo by Robina Weermeijer on Unsplash

A longtime California cardiologist with a background in San Diego and at Stanford University, Sanjiv M. Narayan, MD, PhD, is recognized for his innovations in the area of atrial fibrillation (AF) care, including a next generation FIRM-assisted ablation approach. Dr. Sanjiv M. Narayan’s work over 15 years generated FIRM, Focal Impulse and Rotor Modulation, and has led to work such as that carried out by Acutus Medical.

Based in Carlsbad, California, Acutus focuses on improving outcomes among patients who live with complex atrial arrhythmias. The core platform at work is an intracardiac mapping system that incorporates dynamic arrhythmia visualization techniques. The underlying electrophysiology technology platform is designed to allow for adaptive, personalized approaches to therapy.

The AcQMap stands as the sole cardiac mapping and imaging system that utilizes “precision ultrasound atrial anatomy reconstruction” in tandem with “high-definition non-contact charge density mapping” in ways that are highly reproducible.

In June 2019, Acutus Medical announced completion of a $170 million financing round that included a $70 million credit facility and $100 million in Series D equity investments. The aim of this new funding is to accelerate commercialization activities, while ensuring the development of a robust global business.

Phase Mapping vs. Electrogram-Based Mapping in Ablation

Sanjiv M. Narayan, MD, PhD, is a professor of cardiovascular medicine at Stanford University in California, where he researches bioengineering techniques for the treatment of cardiac arrhythmias. A former professor of medicine at UC San Diego, cardiologist Sanjiv Narayan is a member of several other research teams as well, focused on advancing understanding of atrial fibrillation (AF).

One such team published a study in Pacing and Clinical Electrophysiology, a peer-reviewed journal, entitled, “Comparison of phase mapping and electrogram-based driver mapping for catheter ablation in atrial fibrillation.” Ablation is a procedure that scars or destroys the heart tissue that allows incorrect electrical signals to be sent to the heart and cause atrial fibrillation. 

After studying 175 articles in the PubMed database, the researchers concluded that one specific method of ablation (driver-guided) showed better outcomes than standard ablation therapies. Additionally, the researchers found that phase mapping is better for guiding ablation than electrogram-based mapping. This supports many studies of AF driver based ablation by many techniques.

Addressing Ongoing Challenges in Dealing with Sudden Cardiac Arrest

Cardiologist Sanjiv M. Narayan, MD, PhD, serves as a professor of cardiovascular medicine at Stanford University and founder of the Stanford Arrhythmia Center, where he leads a team working on bioengineering techniques to treat cardiac arrhythmias. Formerly a faculty member at the University of California, San Diego, Dr. Sanjiv Narayan is a researcher who has published numerous articles in leading peer-reviewed medical journals.

One of the leading causes of heart-related deaths worldwide is sudden cardiac arrest (SCA), which only 10 percent of patients survive when it occurs outside of a hospital setting. There has been extensive research into the condition, yet challenges remain. Recently, Dr. Narayan was among a team of researchers to address the hurdles to attacking the SCA epidemic worldwide. This was covered in a recent study by Dr. Narayan in the Journal of the American College of Cardiology, which discussed SCA, new approaches and the use of artificial intelligence to integrate new technologies in the space. 

One practical way they have identified to improve response involves increased community access to technology such as automated external defibrillators. Additionally, the disease may be better understood by further refining SCA classification and by looking at how pathology and physiology determine how the disease presents and progresses. It is also vital that public leaders, lawmakers, and other stakeholders work together to formulate public health policy to adequately address the epidemic.

FDA Approves TactiCath SE for Ablation Treatment

Longtime professor of medicine Dr. Sanjiv M. Narayan has held teaching roles at colleges throughout California, including UC San Diego. He is currently a faculty member at Stanford University and the director of the Stanford Arrhythmia Center. A committed cardiologist and researcher, Sanjiv Narayan, MD, PhD, is a leading authority in the diagnosis and treatment of atrial fibrillation.

In January 2018, the United States Food and Drug Administration gave approval for the use of a new type of ablation catheter for the treatment of atrial fibrillation. Developed by Abbott, the TactiCath Contact Force Ablation Catheter SE (Sensor Enabled) discourages the electrical stimulations that can scar heart tissue. 

Physicians who have tried the catheter have praised it as a major advance in ablation therapy. Srijoy Mahapatra, MD, of Abbott says the TactiCath SE is the latest innovation in the company’s mission to advance ablation therapy by making it safer and easier to perform.

The Heart Rhythm Society Provides an Online Resource for Professionals

Sanjiv M. Narayan, MD, PhD, is a cardiologist serving Stanford University as a professor of medicine who focuses on innovative bioengineering solutions for treating arrhythmias and other cardiovascular conditions. A former professor of medicine at UC San Diego, Sanjiv Narayan additionally supports professional organizations such as the Heart Rhythm Society (HRS), which encourages the highest possible standards in the delivery of healthcare as part of its mission of education and the promotion of research and heart-healthy public policy. 

The society, based in Washington D.C., serves the professional cardiology community and the general public as a major destination for information on electrophysiology and cardiac pacing. Its membership includes professionals from dozens of nations who focus on studying and treating heart arrhythmias. 

As part of its educational efforts, HRS offers a range of continuing medical education courses for professionals in the field, with registration information detailed at its website’s Learning Center. 

Among these courses is one on atrial fibrillation ablation, providing a full review of the topic, as well as information on emerging procedures. Another course discusses mapping in the treatment of AF, and still another provides updates on the use of medical devices to treat heart conditions.

HRS also provides select access to online discussion portals, such as one offering hundreds of hours of presentations taken from the organization’s latest annual Scientific Sessions conference, held in May 2018 in Boston. 

San Francisco will be the site of the 2019 Scientific Sessions in May, with full details provided on the HRS website.

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.