Anand Prasad, MD, interventional cardiologist at University Hospital, Associate Professor of Medicine at University of Texas Health Science Center San Antonio.
Interview Conducted by Ivanhoe Broadcast News in August 2017.
This is a pretty ingenious thing, forty percent of the contrast dye get shunted away from the kidneys, what do you think about that as a person who has being doing surgery for quite some time?
Dr. Prasad: Acute kidney entry or contrast nephropathy is a major problem in the United States and worldwide. The contrast dye itself is harmful to patients, and our goal is to prevent kidney entry after cardiovascular procedures. Our approach to this issue is twofold. One we want to give fluids to these patients to make sure that they are well hydrated and they can excrete out the contrast dye, and second when we are doing the procedure we really want to use as little contrast dye as possible. What we have learned over the past several years is that we probably use more contrast dye than we need for these procedures. Most operators take a syringe of contrast, they inject it in the patient, and they get an image, but we can actually lower the amount of dye that we are giving these patients by using novel technology the DyeVert from Osprey Medical. This is a technology that actually diverts away about forty percent of the dye from the patient into a reservoir, and at the same time does not compromise the image quality so we can actually still make a diagnosis.
So you can still see what you were seeing before this happened, right?
Dr. Prasad: Absolutely, the idea is to find that balance between image quality and dye savings.
When you have a patient like Mary, she has multiple health issues, how much of a game changer is something like this?
Dr. Prasad: Someone like Ms. Bowlin, she is going to get multiple procedures over time. She has had bypass surgery and now is having heart failure symptoms, and she has a worsening aortic valve stenosis and may need a TAVR (transcatheter aortic valve procedure). Those patients are particularly at risk of acute kidney entry, so when someone needs multiple procedures one after another, each procedure put them at risk for worsening kidney damage and so if we can save the contrast dye at each step we can then prevent a worse outcome in terms of her kidneys.
Doctor is the contrast dye going into the kidneys a real problem, or is it that the kidneys have to go into overdrive to get rid of it, or what is the real impact of that?
Dr. Prasad: The dye itself is directly toxic to the kidneys and when someone has impaired renal function they do not excrete the dye out as quickly as they should, so it sits there causing more and more damage. We know that even a small amount of contrast dye in a vulnerable patient can put their kidneys at risk and that risk is not only bad in the short term, but has been shown to increase re-admissions for hospitalizations for heart failure, for instance. Or lead to worsening kidney failure and the need for dialysis later in life.
How much injury can this dye do to kidneys even in a healthy person, much less than someone whose health is compromised?
Dr. Prasad: The risk is not zero in a healthy person, but it is quite low. The risk begins to increase when you add risk factors such as diabetes, heart failure, previous contrast administration; these things are all added as risk factors. Age is an important factor, low blood pressure, the acuity of the situation, if a patient is in shock, or having a heart attack; then the contrast dye is particularly harmful, so the rates can be quite low but reach as high as forty percent or more in vulnerable populations.
Does this give you more peace of mind when you are performing the procedure? Also does it give you an increased amount of time, so that you are not rushing to get done so that the dye doesn’t affect the kidneys?
Dr. Prasad: Rather than impacting the time during the procedure, it does allow us to be more complete in our therapy. Patients who now present with multiple blockages, the recommendations are shifting to try to fix as many of those blockages in one setting as possible. The contrast dye limit was an important factor preventing that, but if we have technology that can decrease the amount of dye that we are using then potentially we can do a more thorough job at the given setting.
If you had to compare this to a ground breaking invention, how does this stack up?
Dr. Prasad: Since the onset and discovery of the techniques of angiography, going back 40 years plus now there really has not been a big change in the way we give contrast in the catheterization lab to patients; it still is a syringe, we inject it through a manifold system into a patient. But now we actually have some effort being made to rethink how we are doing this and come up with a new way that might be better, so it is a big advance. No one has really touched this field in the past several decades.
How many hospitals or how many physicians are employing DyeVert?
Dr. Prasad: I believe now the technology is disseminated much more broadly – it started here in San Antonio in terms of its use and now there are sites all across the country. It is still relatively new product and still being explored; new iterations of the device are coming out on a semi-yearly basis now.
What is the financial tie-in between the manufacture and the hospital?
Dr. Prasad: The device itself costs a few hundred dollars. There is no specific reimbursement for using the device, but I think hospital systems that have used the device are interested; not because they make money directly by using it but because they may prevent re-admissions which cost hospitals money, they may lead to an outcome, so as opposed to a stent, or a balloon that might be tied to a reimbursement this device actually cost some money up front, but may save some money down the road.
As a physician who does a lot of research and you see this coming down the pipe, how exciting is it to finally see the FDA say yes, and you are able to utilize it?
Dr. Prasad: The first versions of the device were quite primitive and I have actually worked with the engineers to help give them ideas on how to improve it and test some of the further iterations of the device; it has evolved from a very primitive device to now a digital screen. It tells the operator how much dye is being used, how much is being saved, so it is quite an improvement over the first generation.
How long does it take for the kidneys to completely get the dye out after a procedure?
Dr. Prasad: In a healthy normal kidney within several hours you can see that all the contrast dye is emptied; interestingly people with renal dysfunction if you image their kidneys you can see the contrast dye still left in the kidney and has not made its way down to the bladder. But that is a relatively crude way of understanding the elimination of the contrast; better methods are using biomarkers and blood tests that are currently being developed.
Briefly we are going to be shooting this behind glass, could you describe to us what you will be doing this morning?
Dr. Prasad: Ms. Bowlin has had prior cardiac surgery, she has had a prior stroke, she has diabetes, she has chronic kidney disease, her heart function has continued to decline and her aortic valve has gotten more and more severe in terms of its stenosis. At this point we are evaluating her for transcatheter aortic valve replacement or TAVR procedure. As part of that workup we want to look at her heart arteries, her bypass grafts to see if they are open, evaluate the pressures in her heart; so this is the next step in her journey towards her transcatheter aortic valve.
END OF INTERVIEW
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