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Interactive Learning : HealthCast Transcripts

Episode 25 : Focus on Blood Clots

Release Date: June 6, 2008

Dr. David Meyerson: Hi, I'm Dr. David Meyerson, Cardiologist at Johns Hopkins, a member of the Scientific Advisory Board for the Vascular Disease Foundation and your host for this edition of Vascular Disease Foundation's HealthCast. We're very excited to be able to bring excellent, easy to understand science to you on all topics relating to heart and blood vessel diseases as a public service. As a public education forum, the Vascular Disease Foundation is made up of representatives of the premier medical and scientific advisory groups in the country that relate to vascular diseases.  These are groups that use peer reviewed science to verify the information you are getting is nationally recognized as the very best and most reliable data available.

We've talked many times before on this program about peripheral arterial disease.  These are narrowings or blockages in the arteries that nourish the legs which can limit your ability to walk, cause pain and create ulcers in the legs and in extreme situations can even cause one to risk amputations. These are largely preventable diseases and once developed, they're very treatable diseases.  The Vascular Disease Foundation is committed to educating you about these are there are many programs that you can listen to on our Web site at that are wonderful topics to choose from on many of these topics.

Today we want to shift gears just a little bit.  We talked just briefly about peripheral arterial disease a moment ago and again the arteries are the conduits that take blood to the muscles, to the periphery of the body and they nourish with oxygen and nutrients all the muscles and tissues that we need to keep active and healthy, but that blood has to get back someplace after it's uses, after the nutrient units are taken out of the blood stream, after the oxygen is transmitted to the tissues.  That stuff has to get back up north as it was, as it were, back to the heart and what, how does it do that?  We have deep, large veins in the legs that collect all the used blood, if you will, and bring it back upstairs to the rest of the body.

The deep veins of the legs are the site of a different type of problem and that's why I've spent a couple of seconds distinguishing between the arteries which take blood downstream or distributes blood to the areas of the body that need it and coming back the veins take blood that is used, the nutrients are depleted, the oxygen is depleted and it takes it back up in the circulation to go back to the heart, back through the lungs again and it comes back all over again.

To discuss this topic of venous thromboembolism, or deep vein thrombosis, or blood clots in the legs, how to recognize them, how to treat them, how to prevent them is my good friend and colleague Dr. Kerry Stewart.  He's Professor of Medicine at Johns Hopkins.  He's Director of Clinical and Research Exercise Physiology here at Johns Hopkins and he is a member of the Vascular Disease Foundation's Scientific Advisory Board and a former member of its Board of Directors.

Kerry, again welcome to the program.  It's always wonderful to have you on microphone.  You are often behind the controls and it's always wonderful when you're in front of the microphone as well.

Dr. Kerry Stewart: Glad to participate.

Dr. David Meyerson: So how do you want to start?  This is an important problem.  People -- this is the summertime, I guess people are getting into cars and going on long car rides if they can afford the gasoline.

Dr. Kerry Stewart: That may be a bigger problem than DVT's I think this summer.

Dr. David Meyerson: And he's really also a comedian. And or people are getting in a plane and you know, they save up for their vacation and they want to go to, on a long plane ride and then they're cramped in a small seat and/or there are others.  Sometimes people hurt their legs and there are a lot of problems that people can get whereby often one of the legs becomes more swollen.  A blood clot can form.

Kerry, as an exercise physiologist, when you see people in the practice at Hopkins, do you often see people complaining of swelling of one side or pain in one side more than the other?  Because I know, if you talk to doctors, doctors will tell you that you can't use the physical examination to tell whether there's a blood clot in the leg, but sometimes patients will be complaining of pain and swelling.

Dr. Kerry Stewart: Well, we see it occasionally, in fact, we don't see it that often because one of the ways in which that this problem can be prevented actually is being physically active, so that people who come to our exercise program are using those muscles, they're pumping and contracting and pushing the blood along back to the heart and --

Dr. David Meyerson: So the muscles of the leg are a critical component of what keeps the blood flowing in the veins.

Dr. Kerry Stewart: Absolutely. That's one of the key factors.  Keep in mind that when you're standing up, blood has to fight gravity.  It has to go from the lower body, back up to the heart which is in the chest and one of the ways in which that happens is by using the legs, the muscles serve as a pump and that helps to push the blood.

Dr. David Meyerson: Again, that's very important to those of you listeners who have good sound systems, you may hear one of our important helicopters probably delivering -- we're the Baltimore Regional Burn Center at this location and other medical transports and if you hear a helicopter in the background, well indeed that's correct, you've heard a helicopter in the background.

Dr. Kerry Stewart: Yeah, when we do these recordings, you know, we unplug the phones and disconnect our beepers, but we have no control over those helicopters.

Dr. David Meyerson: Exactly, exactly.  So in any event, one of the things that we want to talk about is that the risk factors, what is a venous thromboembolism or a blood clot that forms in the legs and why is it important?  So, if somebody's been bedridden for a period of time, if they've had an orthopedic injury, that's pretty important.  If they've had a cast on their leg, or like I said, they haven't been immobile --

Dr. Kerry Stewart: Have had recent surgery.

Dr. David Meyerson: Absolutely, recent surgery.  Some of our patients who have cancer of one form or another are more at risk of blood clots forming in the leg and if, even normal people however, if they've been riding in a car for a very long period of time, if we have an older person who just sits in one position for very long periods of time or if they have other problems with their legs such as edema or swelling, these are people that can have a higher incidence of blood clots forming.

Dr. Kerry Stewart: Right.

Dr. David Meyerson: And the danger, of course, is that these blood clots that form in the deep veins of the legs can occasionally break off and go up in the circulation following where the blood goes back and as I mentioned to you, the blood goes back up the -- if you follow the veins from the leg, it will go from the deep veins of the legs up into the inferior vena cava which is the large vein in the abdomen and that then goes up and actually attaches ultimately to the bottom of the right atrium which is the right upper chamber of the heart.  And the right atrium then spills into the right ventricle and the right ventricle then pushes blood into the lungs.

Now the lungs end up, this is a situation where the little blood vessels of the lungs gets so tiny that, and then they mix with the air sacs and that's how air gets exchanged, oxygen goes into the blood stream and carbon dioxide goes out because it's very, very fine little blood vessels that line the air sacs and that's where the rubber meets the road in terms of getting oxygen in the body and getting carbon dioxide out and the reason I'm bringing this up is that if you follow the stream, the blood stream going back up towards the heart, if you have a blood clot that goes back upstairs, it's going to go up the vena cava, it's going to go into the right atrium, it's going to go past the tricuspid valve, it's going to go into the right ventricle, it's going to go past the pulmonic valve, but then it's going to end someplace because when it goes into the lungs, then it goes into those fine little areas and smaller, smaller segments and it gets trapped in a segment of the lung.

Dr. Kerry Stewart: Right.

Dr. David Meyerson: And when this happens, it's called a pulmonary emboli.  Now these can be smaller sized and not life threatening or larger size and totally life threatening and that's why we want to be able to prevent them, we want to recognize them early, we want to get them investigated and properly treated.

Dr. Kerry Stewart: I think that's a very critical point about this whole topic is that a deep vein thrombosis by itself is usually not life threatening.  Obviously, it can cause symptoms, it causes swelling, people are uncomfortable, they may not be able to walk without pain, but when it breaks off and hits the lungs, that is when emergency treatment is needed immediately.  And in fact, it's estimated that about sixty thousand people a year in the U.S. die from a PE and it's the third most common cause of vascular death.

Dr. David Meyerson: That's absolutely right and again what happens is that the blood clot obstructs some of the circulation to the lung, a segment of the lung can actually die and you can have something called a pulmonary infarct or it can put very, very intense strain on the right of the heart, both can cause heart arrhythmias and shortness of breath, etcetera, so these are, these are very important.  So how --

Dr. Kerry Stewart: And it's important that if you think you have a DVT to get it examined immediately because if you do get a pulmonary emboli, most people will die within an hour or two so it has to be treated emergent -- not urgently, not casually, but emergently.

Dr. David Meyerson: Well let me just clarify that just a bit.

Dr. Kerry Stewart: I wasn't clear enough?

Dr. David Meyerson: There are many people that will have episodes of abrupt onset of shortness of breath.  In other words, the patient will tell us that doctor I was fine one second and then the next second as if I turned on the light switch, then all of a sudden I felt something in my chest, I was -- and they can't tell you exactly what it was, but they say that the shortness of breath comes on profoundly and quickly and those people are at risk, but not everybody who gets a pulmonary emboli is going to die in the first hour or two, but there is a significant percentage of people who do die and the fact that you have one may be a warning that you're about to have another, so I think Kerry's advice, if you start to feel abrupt onset of shortness of breath, or chest pain, or breathing that's worse with, difficult breathing and pain while you breath with deep inspiration, those are some of the clues that you really do need to get investigated in the emergency room promptly.  This is not the kind of thing where you go home, you pack a bag, you go to the bank first, or you pay some bills or have dinner first. When you feel these symptoms, you go right to the emergency room.

Dr. Kerry Stewart: Yeah, let me refer our readers to a pamphlet that we have on the VDF Web site, which is and that pamphlet is known, is called Focus on Blood Clots and it has quite an extensive list of the possible symptoms that people might come down with if they are having a PE and these include what you just said, shortness of breath, sharp chest pain, a feeling of apprehension, perhaps sudden collapse, rapid pulse, coughing, sweating, bloody flem are among the key symptoms that could mean a PE.

Dr. David Meyerson: Now some of these can also come from the pneumonias or heart attacks --

Dr. Kerry Stewart: Correct.

Dr. David Meyerson:  -- or heart rhythm disturbances, etcetera, but among the symptoms that you must not ignore are the ones that Kerry just listed.

Dr. Kerry Stewart: So David, so when someone does have these problems and they go to the emergency room, how is the diagnosis made?  How do you distinguish a PE from something else?

Dr. David Meyerson: Well, you know, pulmonary emboli are very life threatening so they're among the first of the list of things that people look at.  Perhaps the list of the most critical things to rule out are, and compare it to them, are heart attacks, ruptures of great blood vessels in the chest called aortic dissection and pulmonary emboli.  Those are probably the big troika, the big three that are the most worrisome, then several of the others are a little bit less life threatening.

What they would do is they would take a look at the oxygen level in your blood.  They would look at an X-ray to see if there was no obvious pneumonia and then, you can put an echocardiogram transducer on somebody's chest.  It takes just a few seconds.  It's a little gel and a specialized microphone that does sound wave investigations of the heart and it could show that the right heart is, the right side of the heart is being strained, but probably in most emergency rooms throughout the country, what they'll do is something called a PE protocol or a pulmonary embolus protocol, CT or CAT scan and what they'll do is they'll put a medicine called dye into one of the veins and then they will scan the lungs to see if they can see evidence of blood clots going to the lungs.  That's probably the quickest and most accurate way that we have of demonstrating pulmonary emboli and hopefully our readers will, our listeners rather will know -- or our readers if they're getting the brochure.  It's available also at by the way, O-R-G.

And those are reasons why you want to go to the hospital emergently, emergently with the symptoms we talked about. But let's back up a little bit.  Let's go back up, what if you -- if somebody -- so they come to clinic and they're doing the, they're about to do their exercise, but you notice that one leg is more swollen than the other.  It's red, it's tender and much more swollen than the other.  Kerry, at that point, you would not exercise that patient.  You would have them go for evaluation, right?

Dr. David Meyerson: Oh sure because again, at that point, if you're suspicious at all of a DVT, you don't want to do anything to dislodge or have a portion of that clot break off and then travel like we talked about earlier to the lungs, which then can cause a worse problem.

Dr. Kerry Stewart: And early diagnosis means early treatment, early treatment may mean total prevention of allowing the blood clot from going from where it is in the deep veins of the legs up to the lungs.

So what would we do in that situation? First, let me reemphasize that if somebody has a leg that's more swollen than the other, if it's tender, if it's more swollen, if it's reddened, this heightens one's index of suspicion that you could have a blood clot in the leg especially if it were to come at a time in your medical life after, for example, let's say you've had an orthopedic injury or let's say you've had a knee surgery or a hip surgery or the leg's been in a cast for a while, or let's say you've injured it and you really haven't been, you've had it in a brace or you haven't been getting around much because maybe you've had bad low back pain and then you notice that one or you've been in a long car ride or long plane ride and you notice that the swelling that -- everybody gets a little bit of swelling, but it went down on one side and the other one stays swollen.  That's enough to ask your doctor, I think I need to be evaluated.

And let me just tell you, interestingly, that every medical textbook currently available will tell you that the physical examination by the doctor to try and rule out deep vein thrombosis is not reliable.  Not that the doctor that you're going to isn't reliable, that the best doctors under the best circumstances given all the data that they have before them, the physical examination just does not tell the story.

So how do we go ahead and find out what's going on?  The easiest way is to get -- and it's painless and it's the cost is minimal and the risk is essentially zero to get the test and that is a doppler or a sound wave examination of the lower extremities. It's very easy for them to put a gel and a microphone tracking the deep veins of the legs.  They can tell whether the flow is free or whether there are any veins that are being, are full of clot.  Those images are usually very, very easy to see.  They're important to recognize and then if you do find that you have new blood clots in the deep, large veins of the legs, then the therapies begin right there and then.  People are often heparinized.  Heparin is a blood thinner.

Heparin works right away so it's given intravenously by a drip and then the next thing that the doctor will do probably is to start you on coumadin which is a blood thinner which is taken usually once a day.  Something called the INR, which is the International Normalized Ratio.  It's a way that we follow how well the coumadin is anti-coagulating the blood.  Some people call it a blood thinner, but it doesn't really thin the blood the way you think.  For example, if somebody had oil that was 5W30 and in the winter time, oil gets thick and in the summer time or the 10W30 oil, it's lighter and thinner, the blood doesn't get thin, thick like that. So when we say it thins the blood, really what it does, is it prolongs the amount of time that it takes for blood to clot and it allows the body to reabsorb the clot that's in the leg and then prevent it from going on upstairs.

Dr. Kerry Stewart: Now you've listed a couple of the risk factors for developing a deep vein blood clot and I think we should not though leave the impression though that this happens primarily to older people because younger people are also at risk, particularly women who are pregnant or women who are using birth control pills, people who smoke.

Dr. David Meyerson: Absolutely.

Dr. Kerry Stewart: And some people have inherited clotting disorders.

Dr. David Meyerson:  Kerry, I always tell you to do this, it's so -- whenever we talk about it.  We must tell our people not to smoke.  It accelerates the hardening of the artery process in the heart and blood vessel diseases throughout the body.  It causes premature aging, it causes cancer, it causes bladder cancer as well as lung and throat cancer, so there's no disease -- we don't have cures that are better than if you are a smoker, you must stop smoking.  So Kerry, as I always tell you, please tell our listeners stop smoking three times.

Dr. Kerry Stewart: Stop smoking three times. Let me, you know just to emphasize that this could happen to young people, I think we all remember the case of the NBC journalist, I think it was David Bloom, who actually died of a clot while covering the Iraq war.  He was --

Dr. David Meyerson: That's exactly right.  I think he was --

Dr. Kerry Stewart:  -- in a cramped up in a small tank or some vehicle of some sort.  I think he actually had a blood disorder that made him more prone to clotting and in fact, developed a clot and he was unfortunately died.

Dr. David Meyerson:  But if you've been in a -- that is a horrible story because he was a young man with young children and this was preventable disease. If you are in a similar situation, not quite in the bank of a tank or an armed personnel carrier, but if you are in the back of a car on a long ride, cramped in the back with luggage and maybe two or three other people, etcetera, or if you're in an airplane with one of those cramped economy seats that we all know too well, the smart thing is to get up periodically.  The smart thing is to not go more than maybe ninety minutes or two hours without getting up and stretching and walking around.  I think that's a very, very good thing.  Some people, I would say consult your doctor, but some doctors, if you're not taking an aspirin on a regular basis, and I'm not telling anybody go out and start taking medicines without talking to your doctor, especially a young woman who could be pregnant or example or something like that.

Dr. Kerry Stewart:  Right.

Dr. David Meyerson:  You just don't want to do anything without talking to your doctor, but it may be the right thing for you to have a small daily aspirin dose especially if you're embarking on a long trip where you know you're going to be cramped like this and then some of our -- this is a great piece of advice for our patients with and our families with patients that are going to have surgery on knees, on ankles, on hips, etcetera.  Any time you go -- or any surgery where you're going to be in bed for a long period of time, if the family asks the medical team, doctor, nurse, what are we doing to prevent blood clots from forming in the legs?  You'll find that you'll often have a very complex protocol, but once in a while, this question is so worth answering, asking rather, because you want to make sure that they are actually doing something pro-actively to prevent the development of deep vein thrombosis or blood clots in the legs and by doing so and by treating those when they are found, then that also prevents pulmonary embolus which is the life threatening blood clot that goes from the veins of the legs up to the lungs.

Dr. Kerry Stewart: Let me just also say that this is such an important problem that similar to what the Vascular Disease Foundation has done with peripheral arterial disease which was the form to be part of the initiative of the PAD coalition which was to bring public awareness of peripheral arterial disease to the American, well actually world-wide community.  The VDF is also involved in the formation of the Vascular Disease Coalition which will again have a similar mission which is to educate the public much more about this whole problem of venous disease.

Dr. David Meyerson: So if you'd like to get more information, let me just repeat the Web site.  The Web site is, dot O-R-G and if you'd like to call toll, you can dial 866-VDF-4INFO, and I'll give you those numbers straight out, that is 888.833.4463 and that triple 8 is just like an 800 number.  It is toll free, 888.833.4463.  Again, for the Vascular Disease Foundation, for Dr. Kerry Stewart, I'm Dr. David Meyerson, yours in good health and we'll see you next time.


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