Breath of Life for Heart Patients--In-Depth Doctor's Interview
Raed A. Dweik, MD, Director of the Pulmonary Vascular Program, Respiratory Institute at the Cleveland Clinic, talks about a breath test that could detect heart failure.
You specialize in breath testing?
Dr. Dweik: Correct.
Do you think people realize what you can detect by just your breath?
Dr. Dweik: Well, this is a big area that is getting attention more recently. We know that we consume oxygen and we produce carbon dioxide. However, I think because of recent technologies we are now finding hundreds, maybe thousands of molecules in the breath. We just recently developed the technology that enables us to measure them at that level.
Is there a specific technology that really put it over the edge for you?
Dr. Dweik: There are different ones you know. There are two big ones. One is the mass spectrometry because it can analyze breath in a detailed way. The other one is the electronic nose, which also can detect small levels of molecules in the breath.
So, what can you tell by your breath?
Dr. Dweik: The breath can really tell us a lot about the person’s state of health or disease. Everything that is in our blood that is potentially volatile will end up being detectable in the breath. That comes from a lot of sources. We are interested in the effect of diseases. Some diseases alter the breath by having higher or lower levels of certain molecules, but we also have to be careful because even the things that you inhale from the environment can be detected in your breath. For example, if you drive on a polluted highway, it can be detected in your breath when you come to the lab. Even our gut bacteria can make certain molecules that we can detect in the breath.
I have heard a little bit about cancer and breath testing, but heart disease seems so out there. Is that right?
Dr. Dweik: Yes, that’s right. We felt the same way. Actually, we were studying patients with kidney disease because their breath smells different, same thing with liver disease. So, we were actually looking for controls for our kidney patients because we were thinking how we could get that control and also have kidney patients with lots of fluid accumulating in their bodies because they don’t have dialysis. So, we thought how could it be more bland than heart failure. Interestingly, when we started looking it stood out. Heart failure patients had clearly a distinct breath print compared to the people who do not have heart failure. We were surprised. We had to do it again and again. We did a testing set and a validation set. We did not believe it ourselves until we double and triple confirmed it.
What is it that sticks out in heart disease that you’re looking for? Is it one particular molecule?
Dr. Dweik: There are a couple of ways you can analyze it in the breath. We can look at specific molecules. When we did, we found things like acetone and pentane that are elevated in the heart failure patients, but that’s not really the big story. The big story is that there are other molecules in the breath. We don’t know what they are exactly now because on the mass spec we see them as peaks. We looked at several of them, but five of those peaks could tell us whether a patient has decompensated heart failure or not. This is really a big deal in that we’re able to tell without overlapping, without making mistakes who has heart failure and who doesn’t. That was exciting for us, but there’s more work that needs to be done to find out what these molecules are and maybe confirm it in larger groups. We did the confirmation within our group even.
It’s hard to understand because heart disease encompasses so much. There are so many different types of heart disease and different causes of heart failure. So, how does that work?
Dr. Dweik: That is another exciting part about this study. Our controls had other heart diseases, but not heart failure. There are patients in the hospital that had another heart problem, but those were quite different than patients who had heart failure. These patients have something called acute decompensated heart failure. These are patients who are bad enough that they are brought into the hospital to be treated and those are the ones we focused on.
Is there a cause of the heart failure?
Dr. Dweik: Heart failure can be caused by many things. I’m not a cardiologist, but I can tell you in general terms that it could be ischemia. For example, heart attacks can cause it and sometimes cardiomyopathy, or bad muscles of the heart, can cause heart failure. A lot of diseases end up with heart failure; so it’s not really one cause that causes heart failure. Regardless of what causes it, if you eventually end up having heart failure we can tell how your breath is different than somebody who does not have heart failure, even if they have other heart diseases also.
Can you explain how the heart breath test works?
Dr. Dweik: There are two major ways of doing breath testing. One is to blow directly into an analyzer that analyzes your breath or the other one is to blow into a collection bag or device and then bring the breath to the device. The device we use here is kind of large. It’s more like the size of a washing machine. In this particular study, the patients in the hospital would blow into a collection bag and then we bring the bag to the analyzer and run it. Then, we find what’s in their breath.
How quick can something be detected?
Dr. Dweik: This can be done right away. It can be done in minutes.
If the device can eventually get down to a marketable size, is it something that could be done for your annual checkup?
Dr. Dweik: That’s what we hope for. There are some other breath tests that you can use in the portable devices as well. So, our hope is that maybe you’ll be able to check it at your physician’s office. If we get it small enough and portable enough, maybe people can check their breath at home and see if their heart failure is getting bad or not. They can maybe check with their physician or they can adjust their medications, but we’re not there yet.
Do you have any results from the study?
Dr. Dweik: For the study that we’ve done, so far it’s 100 percent accurate. We know that will probably not translate into the real world unless we start doing it in larger populations, but in our studies both the testing cohort and the validation cohort was 100 percent accurate. Of course that’s always true for studies because we had selected patients. In our study that was published, we had about 16 controls, 25 patients who did the testing set, and 36 did the validation set. So all together you do the math, like sixty one patients and sixteen controls.. The test did not misclassify any heart failure patients as controls or any controls as having heart failure, which is very exciting.
Is there a part of this test that can predict how bad your heart disease is getting?
Dr. Dweik: That is what we’re working on now. We are noticing that their breath print changes. So, even if you have heart failure your breath looks different than if you have heart failure that’s decompensated. We are working on answering that question.
So it is a simple, noninvasive test?
Dr. Dweik: That’s the major advantage of breath testing. Compared with a blood test where you have to be poked by a needle or have to get an x-ray, breath testing is noninvasive. So, we can do it anytime. Because the classic breath test is the breathalyzer test, if you can do it on the side of the street you can do it practically anywhere. That’s the advantage of that test.
So heart disease is one. Can this be translated to every kind of disease then?
Dr. Dweik: Absolutely. We are working on liver disease and kidney disease now. We have submitted our work for publication and hopefully it will be coming out soon. These are the obvious ones. We’re looking at asthma. Asthma is one of the first diseases to be looked at and there’s already an FDA approved test to monitor their disease; so that’s exciting as well.
END OF INTERVIEW
This information is intended for additional research purposes only. It is not to be used as a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or accuracy of physician statements. Procedures or medicines apply to different people and medical factors; always consult your physician on medical matters.
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