James Ong, M.D., F.A.C.C., President and Medical Director

1980-1984 Bachelor in Biochemistry, U.C. Berkeley, graduated with honor.
1984-1989 Doctor of Medicine, U.C. San Diego
1989-1992 Internship and Residency in Internal Medicine, UCLA./West Los Angeles VA Program. Selected as Solomon Scholar.
1992-1995 Fellowship in cardiology, Cedars-Sinai Medical Center.  Received Eliot Corday Fellowship.
1995-1996 Fellowship in Cardiac Electrophysiology, Cedars-Sinai Medical Center. Awarded American College of Cardiology Merck Fellowship.
1996-1997 Faculty attending physician, Cedars-Sinai Medical Center. Awarded American Heart Association Grant to study atrial fibrillation.
1996-1997 Clinical Assistant Professor, UCLA/Cedars-Sinai Medical Center -  Awarded grant from National Institute of Health to study atrial fibrillation.
1997-1998 Director of Electrophysiology, Encino-Tarzana Regional Medical Center
1998-date Director of Electrophysiology, Northridge Medical Center
2004-date Founder and Director, Heart Rhythm Specialists of Southern California


A board-certified Cardiac Electrophysiologist, Dr. Ong has been performing complex procedures for arrhythmias since 1993. He began his practice in the San Fernando Valley in 1997, serving as the director of Electrophysiology at several local Regional Medical Centers. His expertise and passion are in the subspecialty area of Cardiac Electrophysiology. He is among the highest-volume operators in Greater Los Angeles area, having performed over 400 Electrophysiology procedures per year in 2005 and 2006.

Born in Taiwan, Dr. Ong grew up in southern California and received all of his education and training in the Golden State. He speaks fluent Mandarin and Taiwanese and studied Latin as a foreign language. Dr. Ong completed his Cardiology and Cardiac Electrophysiology Fellowship at Cedars-Sinai Medical Center, under the auspice of well known cardiologists like Jeremy Swan, William Ganz, James Forrester, P.K Shah, C. Thomas Peter, and Peng-Sheng Chen . On graduation from the program, he was nominated to be a faculty physician whose job was to conduct research in atrial fibrillation and to train young physicians on how to perform procedures in Electrophysiology. He is the author of several scientific manuscripts in the area of Cardiac Electrophysiology, and in particular, on the subject of atrial fibrillation. During his training and teaching career, he was the recipient of many awards from NIH and AHA.

Dr. Ong performing mapping study for atrial fibrillation at Cedars-Sinai Medical Center.


In 1997, Dr. Ong came to San Fernando Valley to establish a comprehensive Electrophysiology program at Encino-Tarzana Regional Medical Center and Northridge Medical Center, caring for patients with arrhythmias ever since that time. As the director of Electrophysiology at Encino-Tarzana Regional Medical Center, he helped build the program into a state-of-the-art, high-volume Electrophysiology Center in the Valley.  He was responsible for upgrading the previous recording system to a new Prucka/GE system, which is still in use today.  At his recommendation, the medical center acquired a new 3-D mapping system in 2007 which will be used to launch the atrial fibrillation ablation program.

Dr. Ong also helped build the Northridge Electrophysiology Division by establishing the first CRT-Biventricular Defibrillator program in the Cardiac Catheterization Laboratory in San Fernando Valley.  He is one of the first local physicians to begin implanting these devices, a new therapeutic modality that has dramatically improved the quality of life for many patients with severe heart failure.

For Los Robles Medical Center in Thousand Oaks, Dr. Ong helped introduced the new 3-D mapping system and started a new program of complex radiofrequency ablation procedures.  He was the first physician to perform such a mapping procedure in Ventura County.

Dr. Ong performing a Radiofrequency Ablation procedure.


In 2004, anticipating the growing needs of subspecialty care for patients with arrhythmias, Dr. Ong began a new chapter in his Electrophysiology career by founding Heart Rhythm Specialists of Southern California, the first medical institution in San Fernando Valley dedicated to the management of arrhythmias.  The timely establishment of this Center served a vital role in San Fernando and Conejo Valley, providing a complete line of diagnostic and therapeutic procedures for patients with arrhythmias.  It actively participates in many clinical researches in order to further our understanding of arrhythmias and improve the care of patients with these conditions.

Procedures that Dr. Ong routinely perform are 1) Pacemaker implantation, 2) Defibrillator implantation, 3) CRT-Biventricular Defibrillator implantation, 4) SVT ablation, 5) VT ablation, 6) Atrial Flutter ablation, 7) Atrial Fibrillation ablation, and a entire list of standard Electrophysiology non-invasive and invasive procedures.

Specialty Board Certification. (http://www.abim.org/who/index.shtm)

American Board of Internal Medicine, certified in Internal Medicine, 1992-2015
American Board of Internal Medicine, certified in Cardiovascular Diseases, 1995-2015
American Board of Internal Medicine, certified in Clinical Cardiac Electrophysiology, 1996-2016

Professional Membership

Fellow, American College of Cardiology, 1997-date
Member, Heart Rhythm Society, 1997-date
Fellow, American College of Chest Physician, 1997-8

Select Lectures and Presentations


Lecture Location Lecture Title
9/17/1997 Posto, Sherman Oaks Non-pharmacological Management of Arrhythmias
12/15/1998 Henry Mayo Medical Center Current Management of Ventricular Tachyarrhythmias
4/15/1999 Encino Medical Center State of the Art in Electrophysiology: Can Electricity Bring Good Things to Life?
6/1999 Fess Parker's, Santa Barbara Dizziness, Seizure, and Broken Hips: What do they have in Common?
7/1/1999 Tarzana Medical Center Pitfalls in EKG Interpretation
7/7/1999 Tarzana Medical Center Electrophysiology for Primary Care Physicians
7/26/1999 Topanga Canyon Mall Irregular Heartbeat: The Link Between Fainting and Sudden Death
7/30/1999 Tarzana ER Physicians Pacemaker and Defibrillators
8/5/1999 Tarzana Medical Center Syncope
9/14/1999 Motion Picture Hospital Drug-Free Treatment for Irregular Heartbeats
11/21/1999 Chinese Baptist Church Heart Disease Prevention
2/21/2000 Mid Valley Gymnasium Irregular Heartbeats in Children and Adults
5/30/2000 Northridge Medical Center Case Studies in EP: Is it VT or SVT
8/25/2000 Fess Parker's, Santa Barbara Case Presentation in EP: When Should you Call your EP Buddies?
11/30/2000 Lancaster Community Med Center Dizziness, Seizure, and Broken Hips: What do they have in Common?
3/20/2001 Northridge Medical Center Syncope
9/4/2001 Northridge Medical Center Atrial Fibrillation: When, Who, and How?
7/20/2002 Chinese Baptist Church, San Diego An Overview of Cardiovascular Diseases in the Elderly
4/13/2002 Chinese Physician Society Meeting An Overview of Cardiac Electrophysiology: What Can Electricity do for you?
9/24/2004 Northridge Medical Center Biventricular Pacemaker and Defibrillator: Cardiac Resynchronization
11/4/2004 West Hills Medical Center An Overview of Cardiac Electrophysiology
1/6/2005 Henry Mayo Medical Center Dizziness, Seizure, and Broken Hips: What do they have in Common?
3/1/2006 Cardiology Grandround: Antelope ValleyMedical Center Implantable Loop Recorder in the Evaluation of Arrhythmia Patients
6/17/2005 Fess Parker's, Santa Barbara Electrophysiology for Dummies
8/19/2005 West Hills Medical Center What is new in Cardiac Electrophysiology?

Select Publications (click here for a complete list of publications)

1 Ong JJC, Sarma JSM, Venkataraman K, Levin SR, Singh BN. Circadian Rhythmicity of Heart Rate and QTc Interval in Diabetic Autonomic Neuropathy: Implications for the Mechanism of Sudden Death. American Heart Journal1993;125:744-52.
2 Ong JJC, Hsu PC, Lin L, Yu A, Kass RM, Peter CT, Swerdlow CD. Arrhythmias Following Cardioverter-Defibrillator Implantation: Comparison of Epicardial and Transvenous Systems. American Journal of Cardiology 1995;75:137-40.
3 Ong JJC, Cha YM, Kriett JM, Boyce K, Feld GK, Chen P-S. The Relation Between Atrial Fibrillation Wavefront Characteristics and Accessory Pathway Conduction. Journal of Clinical Investigation 1995;96:2284-96.

Ong JJC, Kriett JM, Feld GK, Chen P-S. Prevalence of Retrograde Accessory Pathway Conduction During Atrial Fibrillation. Journal of Cardiovascular Electrophysiology 1997;8(4);377-387.

5 Chen P-S, Wu T-J, Ikeda T, Ong JJC, Kim Y-H, Yashima M, Doshi R, Hwang C, Karagueuzian HS: Focal source hypothesis of atrial fibrillation.  J Electrocardiol. 1998;31 Suppl:32-4.
6 Doshi RN, Wu TJ, Yashima M, Kim YH, Ong JJ, Cao JM, Hwang C, Yashar P, Fishbein MC, Karagueuzian HS, Chen PS. Relation between ligament of Marshall and adrenergic atrial tachyarrhythmia.  Circulation. 1999 Aug 24;100(8):876-83.
7 Wu TJ, Ong JJ, Chang CM, Doshi RN, Yashima M, Huang HL, Fishbein MC, Ting CT, Karagueuzian HS, Chen PS.Pulmonary veins and ligament of Marshall as sources of rapid activations in a canine model of sustained atrial fibrillation. Circulation. 2001 Feb 27;103(8):1157-63.


Linda Tseng-Ong, M.D.

1985-1986 Universite de Pau et Universite de Paris, France
1982-1987 Bachelor of Arts, Bioengineering, U.C. San Diego
1987-1989 Oral Robert University, School of Medicine
1989-1991 Doctor of Medicine, Loma Linda University
1991-1993 Internship, Medicine/Pediatrics Combined Program, Loma Linda University
1993-1995 Residency, Pediatrics, U.C.L.A.
1995-1998 Fellowship, Pediatric Neurology, U.C.L.A.
1998-1999 Fellowship, Neuromuscular Diseases, U.C.L.A.
1999-date Assistant Clinical Professor, Pediatric and Neurology, U.C.L.A.
2000-date Assistant Clinical Professor, Pediatrics and Neurology, University of Southern California
2006-date President, Pediatric Neurology Group


As the vice President of Heart Rhythm Specialists of Southern California, Dr. Tseng-Ong helps oversee the day-to-day operation of the Center, but her professional interest is in the area of Pediatric Neurology.  She attended two medical schools, trained in both Internal Medicine and Pediatrics, completed two sub-specialty training fellowships, and has the title of Assistant Professor at two Universities.   

Dr. Tseng-Ong's most recent tenure was a faculty physician at Children's Hospital of Los Angeles, where she taught fellows and residents in Pediatric Neurology and conducted research in this field.  She has published several scientific papers in this area.

In 2006, Dr. Tseng-Ong left academic medicine to start private practice but continues to attend the Muscular Dystrophy Clinic at UCLA, helping indigent patients with severe neuromuscular disorders.  In 2007, she launched Pediatric Neurology Group in Tarzana to begin her private practice seeing patients in Pediatric Neurology.

Dr. Tseng-Ong's specialty includes the area of 1) Muscular Dystrophy, 2) Seizure, 3) Cerebral Palsy, 4) ADHD.  She is fluent in several foreign languages including Mandarin, Taiwanese, Spanish, and French.

Specialty Board Certification

American Board of Pediatrics, certified in Pediatrics, 1995
American Board of Psychiatry and Neurology, certified in Neurology with special qualification in Child Neurology , 2000-2010

Professional Membership

Associate Member, American Academy of Neurology
Associate Member, American Academy of Pediatrics
Member, North America Taiwanese Medical Association