Kelly Okray, PA-C, MSPAS
Physician Assistant
6570 W. Avenue L-12
Lancaster, CA 93536
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Availability last updated 05/15/2026
Kelly Okray, PA-C, MSPAS
Physician Assistant
6570 W. Avenue L-12
Lancaster, CA 93536
Dr. Barry Buffman has been practicing since 1980 in internal medicine with a specialty in urology. He graduated from the Rush Medical College in Chicago, IL and practices with a focus on a multitude of urological issues, such as sexual dysfunction, bladder, and prostate conditions. In addition, Dr. Buffman is involved with medical research for various urological conditions. In his spare time Dr. Buffman has a passion for teleplay/screenplay, musical composition, guitar, and piano.
Dr. Barry Buffman, MD
Urologist
6570 W. Avenue L-12
Lancaster, CA 93536
Kanagaratnam Sivalingam, MD, FACP, is a skilled internist at First Valley Medical Group in Lancaster, California. He has more than 40 years of experience in treating numerous acute and chronic conditions. Dr. Sivalingam spends time with patients and listens to their concerns, giving them a voice in their treatment.
Dr. Sivalingam earned his medical degree from the University of Ceylon Medical School in Peradeniya, Sri Lanka. He completed his internal medicine training at the Hospital for Joint Diseases in New York City and his residency at Vembadi Polyclinic in Ceylon, Sri Lanka.
He maintains his advanced credentials with continuing education. Dr. Sivalingam is board certified in internal medicine and licensed in the state of California. He’s a fellow of the American College of Physicians and a member of the American Medical Association, American Society of Echocardiography, American Academy of Anti-Aging Medicine, and numerous other professional organizations.
At First Valley Medical Group, Dr. Sivalingam provides premium care for patients with a variety of chronic diseases using a compassionate bedside manner. He uses the most innovative technology and procedures to provide expert treatments.
Dr. Sivalingam evaluates each patient as a whole person and offers conservative treatments whenever possible. He and his team warmly welcome patients to First Valley Medical Group and look forward to serving them.
Dr. Kanagaratnam Sivalingam, MD
Geriatrician
6570 W. Avenue L-12
Lancaster, CA 93536
Kanagaratnam Sivalingam, MD, FACP, is a skilled internist at First Valley Medical Group in Lancaster, California. He has more than 40 years of experience in treating numerous acute and chronic conditions. Dr. Sivalingam spends time with patients and listens to their concerns, giving them a voice in their treatment.
Dr. Sivalingam earned his medical degree from the University of Ceylon Medical School in Peradeniya, Sri Lanka. He completed his internal medicine training at the Hospital for Joint Diseases in New York City and his residency at Vembadi Polyclinic in Ceylon, Sri Lanka.
He maintains his advanced credentials with continuing education. Dr. Sivalingam is board certified in internal medicine and licensed in the state of California. He’s a fellow of the American College of Physicians and a member of the American Medical Association, American Society of Echocardiography, American Academy of Anti-Aging Medicine, and numerous other professional organizations.
At First Valley Medical Group, Dr. Sivalingam provides premium care for patients with a variety of chronic diseases using a compassionate bedside manner. He uses the most innovative technology and procedures to provide expert treatments.
Dr. Sivalingam evaluates each patient as a whole person and offers conservative treatments whenever possible. He and his team warmly welcome patients to First Valley Medical Group and look forward to serving them.
Dr. Kanagaratnam Sivalingam, MD
Geriatrician
44725 N. 10th Street West
Suite 170
Lancaster, CA 93534
Dr. Barry Buffman has been practicing since 1980 in internal medicine with a specialty in urology. He graduated from the Rush Medical College in Chicago, IL and practices with a focus on a multitude of urological issues, such as sexual dysfunction, bladder, and prostate conditions. In addition, Dr. Buffman is involved with medical research for various urological conditions. In his spare time Dr. Buffman has a passion for teleplay/screenplay, musical composition, guitar, and piano.
Dr. Barry Buffman, MD
Urologist
44725 N. 10th Street West
Suite 170
Lancaster, CA 93534
Kelly Okray, PA-C, MSPAS
Physician Assistant
44725 N 10th Street West
Suite 250
Lancaster, CA 93534
Sooraj Shah
Internist
1640 Newport Blvd Suite 445
Costa Mesa, CA 92627
Teferi Mitiku, MD, FACC, is a board-certified cardiologist in Clinical Cardiac Electrophysiology and Cardiovascular Disease. He specializes in cardiac electrophysiology (EP) and provides the entire spectrum of arrhythmia treatments, including medical therapy, catheter ablation, and device-based therapy. Dr. Mitiku strives to provide compassionate care for his patients at Coastal Cardiology of Orange County in Irvine and Ladera Ranch, California.
Dr. Mitiku earned his Bachelor of Science in molecular cell and development biology from the University of California, Los Angeles (UCLA), graduating magna cum laude. He went on to attend the David Geffen School of Medicine at UCLA, receiving his Doctor of Medicine.
He then completed his internship and residency in internal medicine at Stanford University Hospital in Stanford, California, before completing cardiovascular medicine and electrophysiology fellowships at Yale New Haven Hospital in New Haven, Connecticut.
He previously served as the Director of Electrophysiology and an Assistant Professor of Medicine in the Division of Cardiology at the University of California, Irvine (UCI) School of Medicine and Wayne State University School of Medicine.
During his academic appointments, Dr. Mitiku enjoys teaching medical students, residents, and cardiology fellows. He was awarded Outstanding Teacher of The Year for three consecutive years and was granted entry into the Gold Humanism Honor Society.
Dr. Mitiku is affiliated with UCI Medical Center in Orange, California, and serves as the director of electrophysiology at Hoag Irvine Hospital in Irvine, California. At Hoag, He was awarded the top quality performer within the Cardiology peer group for 2019 and 2020. He is also a member of the American Heart Association, American College of Cardiology, and the American Medical Association.
He looks forward to welcoming new patients and providing excellent care for those continuing at Coastal Cardiology of Orange County.
Dr. Teferi Mitiku, MD
Internist
16305 Sand Canyon Ave
Suite 255
Irvine, CA 92618
Dr. Nguyen grew up in Irvine and received his Bachelor of Arts in biology from the University of California, Irvine.
He then earned a master's in applied physiology and earned his medical degree from Chicago Medical School, one of the graduate schools of the Rosalind Franklin University of Medicine and Science in North Chicago, Illinois.
Back in Orange County, he completed his internship and residency in internal medicine, as well as his fellowship training in general cardiology, all at UC Irvine Medical Center in Orange, California.
He then moved to New York to complete his interventional cardiology fellowship at Mount Sinai Hospital in New York City, where he was awarded Outstanding Interventional Cardiology Fellow of the Year.
Throughout the course of his training, Dr. Nguyen has given numerous lectures and presentations, and has authored publications in peer-reviewed journals on various topics in both general and interventional cardiology.
He was involved with and participated in live case demonstrations at Mount Sinai Hospital, focusing on complex coronary interventions.
Dr. Nguyen believes in a patient-centric approach to cardiovascular care and focuses on the collaborative efforts with his patients in optimizing their outcomes.
In his spare time, Dr. Nguyen enjoys spending time with his family, watching movies, playing basketball, and surfing.
Dr. Huy Nguyen, MD
Internist
16305 Sand Canyon Ave
Suite 255
Irvine, CA 92618
Brett Wertman, MD, FACC, is a triple board-certified cardiologist who is widely respected for his treatment and care for patients at Coastal Cardiology of Orange County in Ladera Ranch and Irvine, California.
Dr. Wertman, who twice has been named a Physician of Excellence by the Orange County Medical Association, also leads the Cardiac Rehabilitation Program at Hoag Hospital Irvine in Irvine.
An Orange County native, Dr. Wertman graduated summa cum laude and with Phi Beta Kappa Society honors in earning his Bachelor of Arts degrees in biochemistry and molecular, cellular, and developmental biology from the University of Colorado Boulder in Boulder, Colorado.
Dr. Wertman then completed his medical degree from the University of Washington in Seattle, Washington, and went on to finish his internship and residency training in internal medicine at Ronald Reagan UCLA Medical Center in Los Angeles, California.
He completed his fellowship training in cardiology and interventional cardiology at Cedars-Sinai Medical Center, also in Los Angeles.
Dr. Wertman has authored numerous publications in leading peer-reviewed journals and participated in live case transmissions to national meetings, demonstrating new techniques in the treatment of coronary artery disease and valvular heart disease.
Dr. Wertman is highly trained in the percutaneous treatment of valvular heart disease, including aortic valve replacement using the Edwards Sapien heart valve system, as well as mitral valve repair using the Abbott MitraClip™ system. He also has significant experience in other novel interventional therapies.
He looks forward to welcoming new patients and offering superior care to those returning to Coastal Cardiology of Orange County.
In Dr. Wertman’s spare time, he enjoys relaxing with his family, traveling, and exercising.
Dr. Brett Wertman, MD
Internist
16305 Sand Canyon Ave
Suite 255
Irvine, CA 92618
Dr. Hilda Riderer was born and raised in Romania and moved to California with her family when she was a young girl at 9 years old.
She always had a passion for medicine so she pursued an education in the medical field going to osteopathic medical school in Denver, Colorado and completing her Internal Medicine residency in Long Beach, California. Her love of medicine developed into a love for aesthetics but also for preventive medicine and she began exploring options in more natural ways to heal the body and make her patients feel healthy and also beautiful from the inside and out.
To date, she’s still very excited to continue the pursuit of preventive medicine offering services such as IV and vitamin infusions but with a touch of aesthetics to help her patients look and feel their best.
Dr. Hilda Riderer
Internist
9201 Sunset Blvd
Suite 212
West Hollywood, CA 90069
Ehsan Ali, MD
Internist
9400 Brighton Way
Ste 303
Beverly Hills, CA 90210
Dr. Barkodar is Board Certified in Internal Medicine. Dr. Barkodar received her medical degree from Albert Einstein College of Medicine. She went on to complete her internship and residency in internal medicine at Cedars Sinai Medical Center. She has a special focus on womens health. She is on staff at Cedars-Sinai Medical Center.
Dr. Linda Barkodar, MD
Internist
9400 Brighton Way
Suite 303
Beverly Hills, CA 90210
Katja Van Herle, md
Internist
436 N Bedford Dr Ste 202
Beverly Hills, CA 90210
Anthony Montuno, MD
Internist
8635 W 3rd St #485w
Los Angeles, CA 90048