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From the OHSU Knight Cardiovascular Institute
Firas Zahr, M.D.
Dr. Zahr is the director of Interventional Cardiology and the co‑director of the OHSU Complex Heart Valve Program. His chief interest is pioneering minimally invasive approaches to treating complex heart and valve diseases.
In February 2018, OHSU became the third institution nationwide to perform a novel transcatheter mitral valve replacement as part of the APOLLO Trial, which is evaluating the safety and efficacy of Medtronic’s Intrepid™ Transcatheter Mitral Valve Replacement, or TMVR, system.
New solution breaks the cycle of hospitalizations for high‑risk patients
Mitral valve regurgitation affects about 4.1 million people in the U.S. Many older patients don’t qualify for traditional open-heart surgical replacement procedures due to overall health and/or co-morbidities. The classic treatment for this demographic has been medical therapy, which often results in multiple hospitalizations for heart failure.
Now, after more than a decade of replacing the aortic valve with a transcatheter approach, the technology has evolved to offer a minimally invasive mitral valve replacement technique. This is very new, and it represents a paradigm shift in treatment options for the patient population at high surgical risk.
The mitral is a tricky valve
Developing a transcatheter replacement solution for the mitral valve has been difficult because of numerous anatomical and physiological challenges. It is a delicate valve with huge variation in size from person to person. Until TMVR, the only transcatheter option was an implant (MitraClip®) designed to improve closure of the valve’s leaflets and reduce leakiness. However, not all patients qualified for this technique, and many need replacement rather than repair of a degraded valve.
The TMVR procedure
OHSU is currently the only center in Oregon participating in the APOLLO trial. We have performed several TMVR procedures. Patients report relief from symptoms and none have been hospitalized for heart failure.
Patients selected for the trial are admitted to OHSU a couple of days in advance of the procedure. During the procedure, we make a small incision on the left side of the chest to slip in the delivery system. We use live-motion X-rays and ultrasound waves to track the device’s movement during insertion. The artificial mitral valve is made of cow heart tissue and includes two wire mesh stents, compressed into a thin capsule. The time from puncturing the heart to deploying the self-expanding valve takes about 10 minutes. The artificial valve works immediately. The whole procedure takes approximately two hours. Patients do not need the heart bypass machine. We usually release them from the hospital within a few days.
Prospects strong for inclusion among valve replacement options
In the past, we had one or two options for minimally invasive repairs for valves, but now we have five or six options. As with any new technology, we must be cautious and thoughtful in rolling TMVR out slowly, but indications are very promising. The artificial mitral valve currently has three sizes available. As a tissue valve, it has the same characteristics as the surgical valve, which has a life span of nearly a decade. We will have to monitor results over time. When we initiated transcatheter aortic valve replacement (TAVR), it was only available to high risk patients. Today, we can offer it to low risk patients. TMVR may follow the same pattern. The main limitation at present is awareness of the technology and enrolling patients to the trial.
Qualifications for APOLLO Trial
- Inclusion criteria is broad for anyone with severe regurgitation and high surgical risk.
- Selection is based on anatomical qualifications.
- Patient evaluation requires a CT scan and echocardiogram to determine anatomical structure.
Another technology we are investigating through a multicenter trial is a mitral valve transcatheter repair option, the Edwards Cardioband System, for patients with moderate to severe functional mitral regurgitation. The device simulates surgical annuloplasty repairs that reconfigure the shape of the valve annulus to reduce or eliminate valve regurgitation. (ACTIVE: Annular Reduction for Transcatheter Treatment of Insufficient Mitral Valve).
If you have questions or would like to refer a patient for evaluation, please call the OHSU Physician Advice and Referral Service at 503-494-4567.