Guest: Dr. John Wang
Presenter: Neal Howard
Guest Bio: John C. Wang, MD, is chief of the Cardiac Catheterization Laboratory at MedStar Union Memorial and scientific director for Baltimore Cardiovascular Research. Dr. Wang is board certified in Interventional Cardiology, Cardiovascular Disease and Internal Medicine. He specializes in minimally invasive procedures that increase blood flow to the heart, diminish chest pain and decrease the risk of heart attack.
Segment overview: In this segment, Dr. John Wang, Chief of Cardiac Catheterization for The MedStar Heart and Vascular Institute at MedStar Union Memorial Hospital discusses Transcatheter Aortic Valve Replacement (TAVR).
Health Professional Radio – Transcatheter Aortic Valve Replacement
Neal Howard: Hello and welcome to Health Professional Radio, I’m your host Neal Howard, thank you for joining us here today. With us today is Dr. John Wang, returning guest, Chief of Cardiac Catheterization for the MedStar Heart and Vascular Institute at Medstar Union Memorial Hospital and he is returning today with us to discuss Transaortic Valve Replacement (TAVR). Welcome in the Health Professional Radio Dr. Wang.
Dr. John Wang: Hi, thank you very much Neal.
N: Thanks for coming back. Now, when we’re here before we talked quite a bit about dissolvable cardiac stents. Now today, we’re here to talk about Transaortic Valve Replacement. For our listeners who may not be familiar with you when you’re here before, tell us a little bit about yourself.
W: Sure. I grow up in Baltimore, Maryland and went to school here at locally. My father was a physician at Hopkins for many years. I then went to college at University of Chicago and medical school at Pritzker School of Medicine there. And my wife is from Boston so we both moved to Boston and did our training at the Brigham and Women’s Hospital, one of the Harvard hospitals. I was there through my internship, residency, and fellowship, and school of public health degree and moved out at Baltimore in 2004. And I’ve been with MedStar Union Memorial and been a chief of the Cardiac Catheters since 2006.
N: You’ve been quite busy for quite a while (laughs).
W: That’s right.
N: Now, transaortic valve replacement, what is it and how does it differ from other replacement procedures?
W: TAVR or Transcatheter Aortic Valve Replacement is actually a technology that was FDA-approved in the United States in 2012. And traditionally, the only way to replace an aortic valve, which is one of the heart valves was with open heart surgery. And I want to back up for a second because not everybody may know about why you would even need a new heart valve. The most common reason patients have problems with their aortic valve, which is the main valve that opens and closes with every beat of the heart that allows blood to get to the rest of the body. That valve, in about 5% of us says we get older, gets narrowed and you developed what’s called ‘Aortic Stenosis’, and that’s usually from calcium build up on that valve. It gets to a point where when it becomes severe or critical and that valve area is less than 1 cm2 (squared centimeter), when normal is between 4 and 5 cm2 (squared centimeters) that patients who have a lot of symptoms of chest pressure, or shortness of breath, or even passing out and having what we called ‘Syncope’. When that happens, the only way to treat this effectively is not with medicines but with a new heart valve. Prior to 2012, the only way to replace that was major open heart surgery and that is incision through the breastbone, putting patients on a heart lung machine, and it is in valve procedure with the fairly long recovery but that was the only option. In 2012, the FDA actually approved this technology called TAVR, which is a way for us to replace this heart valve by actually going through the femoral artery or a leg artery and sneaking up a small catheter crossing the old heart valve that calcified, expanding it with a balloon and implanting a new heart valve that’s actually mounted on a stent. And all of this is done while the patient is asleep but sedated, while their heart is beating and it’s a much faster recovery for these patients.
N: It sounds extremely in valve, but as you say a lot less invasive than cutting through the chest but still it’s amazing to me that you can go that far up the body from that a low point.
W: Yes. And what’s really remarkable is that this procedure even in the short amount of time from 2012 till now 2017, has evolved to becoming much, much smaller in the actual size of the catheterize necessary to deliver this new heart valve. We have patients literally going home the following day after this procedure. This procedure has become much more similar to a heart catheterization procedure than an open heart procedure and again, effectively doing the same thing which is replacing that diseased aortic valve.
N: Is there a candidate who just isn’t going to benefit from this or is this the now big thing, not even the next big thing, who benefits from this?
W: At present, as with all new technologies, they are always approved and tested in the sickest of patients. And so when this was actually approved in 2012, it was only approved for patients that are what we called ‘inoperable or extreme risk patients’. Then, the FDA soon approved this after they were studied and patients who are high risk for traditional aortic valve surgery. Since then, they’ve also been improved in patients that are intermediate risk for open heart surgery and now we are actually one of only a few centers in the country studying this technology in what we call ‘low risk or standard risk patients’. In addition to the risk determination for traditional open heart surgery, there are some subset of patients that still benefit from traditional open heart surgery. Those are primarily patients who have what’s called of ‘Bicuspid Aortic Valve’ and the normal aortic valve has 3 leaflets but about 1% of us are born with congenital abnormality called of bicuspid aortic valve which only has 2 leaflets. Those patients developed aero stenosis much sooner in life usually in their 5th or 6th decade of life and in those patients, they often have disease of their ascending aorta as well and those patients tend to do better with traditional open heart surgery.
N: Have you noticed that candidates who have been on statins, benefit less or more than those who have not?
W: There are some small reports about statins affecting heart valve progression. However, really when we think about statins Neal, this cholesterol lowering medicines, we’re really thinking about their ability to prevent progression of coronary plaques or the cholesterol narrowing in the coronary arteries, so it really separate from the aortic valve.
N: Do you think that a patient who might benefit borderline from traditional open heart surgery because of their health or their age, all of the sudden now that this technology is available to them, maybe doing that type of surgery even though they are still at an age that might not qualify for additional effort?
W: Well, every day, we see patients that if they’re warn for this technology we have in their options. So, there are many patients now that have options, they can get a new heart valve and get back to an active lifestyle that otherwise would not have been surgical candidates or if they underwent surgery, it would have been a very, very high risk. So yes, absolutely every day we’re seeing those patients.
N: Now Dr. Wang, I understand that there’s a new study, a low risk study involving this replacement procedure, can you talk about that study?
W: Thanks Neal. So TAVR, as I stated earlier, is already approved in extreme risk patients, high risk patients, and intermediate risk patients, and the only subset left to have this technology studied in is low or standard risk patients. And we are one of 80 centers in the United States participating in this low risk TAVR trial. So, we actually have access to this technology for low risk patients under an FDA-approved trial. So when patients get diagnosed with severe aortic stenosis and it is determined that they need to have a new aortic valve if they are on low risk, traditionally, their only option was to go for open heart surgery. Now, if they decide to participate in our low risk TAVR trial, they will be randomized. So there’s a 50% chance that they will get TAVR and a 50 % chance that they will get traditional aortic valve surgery. But at least it gives our options of 50% chance of a less invasive way to replace their aortic valve.
N: Now, is this participation initiated by the patient once they are briefed on their condition or is this something that has to happen with the physician even present it to them? Is this something that the patient can know about beforehand?
W: Patients can find out more about this through our website to find out more information about transcatheter aortic valve replacement. But the way the process works is that first, patients are diagnosed with aortic stenosis. After they are diagnosed with aortic stenosis, they will be seen by a cardiac surgeon as well as by an interventional cardiologist in a heart team approach. And we will discuss with the patients their options including participating in this trial. If patients are interested in finding out more about this trial and participating, they will be met with our research coordinator, have adequate time to review the informed consent and have their questions answered. And then after signing the informed consent process, there are some minor non-evasive tasks that have to occur. And then once they go through that process, they can be randomize. They can again be randomized to either traditional open heart surgery or TAVR, which is a less invasive way to replace the surgery. The time period from the time you get diagnosed with aortic stenosis, to the time you actually signed the consent form and then ultimately get randomized and get your therapy is usually within a couple of weeks. So, you can Google the MedStar Heart and Vascular Institute or MedStar Union Memorial Hospital. We have a very large heart valve center here, we’ve done over 350 of these transcatheter aortic valve replacement surgeries with excellent outcomes.
N: Well I thank you for talking with us today Dr. Wang.
W: Thank you.
N: You’ve been listening in the Health Professional Radio, I’m your host Neal Howard, in studio with Dr. John Wang, Chief of Cardiac Catheterization for the MedStar Heart and Vascular Institute at MedStar Union Memorial Hospital. Transcripts and audio of this program are available at healthprofessionalradio.com.au and also at hpr.fm, and you can subscribe to this podcast on iTunes.