Blood Clots, DVTs and PEs, Oh My!

Carbon Health Editorial Team
December 2, 2022
10 Min

Blood Clots, DVTs and PEs, Oh My! A Discussion With Rob Swanda, PhD and Dr. Aaron Weinberg

In an effort to make science and healthcare information accessible, Carbon Health has partnered with Rob Swanda, PhD to answer questions about blood clots, deep vein thrombosis and pulmonary embolisms, from actual people (via Dr. Swanda’s Twitter followers). Dr. Swanda is joined by Dr. Aaron Weinberg, the national director of clinical research at Carbon Health, to tackle blood clotting, DVT and PE related questions below, and many more in the full-length video discussion found near the bottom of this post.

What are some deep vein thrombosis (DVT) & pulmonary embolisms (PE) stats?

Dr. Weinberg: “DVT and PE, is a very common condition actually and most people are not aware of that. And I usually joke around and say that DVT and PE hired a bad PR firm and the reason being is that there's a lack of general awareness about how common this condition really is. We all know about heart attacks, we all know about strokes, we can probably recite the signs and symptoms of each of those conditions. But, when you ask someone what is a DVT or PE, most people look puzzled and kind of vaguely know what you're talking about. But, DVT and PE are the third leading cause of cardiovascular death in this country behind heart attacks and strokes. It's very common. Over a million people in the U.S. are diagnosed with it per year. And unfortunately it's very deadly. Over a hundred thousand patients in the U.S. die of pulmonary embolism (PE) every year and unfortunately sometimes you don't even know you have the condition until you're already dead. There's been multiple autopsy studies out there with hundreds of patients that show the correct pre-mortem before death diagnosis was only made in less than 10 percent of the cases. So, there needs to be more understanding both in the general population as well as with health care professionals out there. And I think one reason I'm so passionate about this condition is that it really affects the whole population. Whether you're young, old, healthy, or sick, everyone is at risk for this.”

What is the point of blood clots?

Dr. Swanda: “Why do we even need blood clots if they're having this negative adverse effect on our health and some of these conditions?”

Dr: Weinberg: “Yeah it's a great question! And usually blood clots are protective. They are actually advantageous as we're going about our daily lives. We bump into things, we play sports, we run into the edge of a table and blood clots act as a control mechanism. So, when we have a trauma they end up going to the area of injury, they plug up the little blood vessels there and prevent catastrophic bleeding. So there always needs to be this balance of the protective nature of blood clots, the ability to form them, but also the ability to not form too many of them. And, if your blood clots too easily or too much then that can cause a whole host of clinical problems. Your body is in the state we call homeostasis where there's this fine balance between doing something too much and doing it too little, and you really want to be in that balanced state. But, there are factors that can tip you in one direction or the other and that's when you develop certain pathologies.”

How do blood clots form?

Dr. Swanda: “So, when these blood clots are necessary to form, how do they actually form in our bodies?”

Dr. Weinberg: “Specifically speaking to deep vein thrombosis, or DVT, those are blood clots that typically form in the legs. The big vessels of your legs, the veins of your legs. And over 95 percent of the time pulmonary embolisms which are what we call the blood clots when they go to the lungs, they start in the legs over 95 percent of the time. Then, they break off and they travel up through your veins, up through the right side of your heart. And if you remember from physiology class back in the day the right side of the heart pumps blood to your lungs to pick up oxygen. So, it takes deoxygenated blood with less oxygen, pumps it back to the lungs to pick up oxygen and then back to the left side of the heart to the rest of your body to oxygenate your organs and your tissues. Now when these blood clots form in the legs and break off they travel through the right side of the heart and then they're pumped into the lungs where they start plugging up the blood vessels of the lungs. And it's a little bit analogous to putting your finger over a hose because when the right side of the heart has to pump against all these plugged up blood vessels it creates a lot of back pressure on the heart and the heart ends up failing. And that's why people die of pulmonary embolism. They actually die from right-sided heart failure. Now you can develop blood clots or deep vein thrombosis of the upper extremities. That's possible with your arms, however that's much more rare.”

Common DVT and PE risk factors

Dr. Swanda: “What are some of the common risk factors for DVT and PE that we can be on the lookout for?”

Dr. Weinberg: “Yeah well there's two kinds of main buckets that I like to group patients in. There's those that have a genetic predisposition, so kind of the things that you really can't modify, you're just born with it. There are those people that have genes that make them more susceptible to forming blood clots and put them at higher risk of this condition. So there's a segment of the population due to genetics that forms blood clots more easily. However, there's also large percentages of the population that develop blood clots due to environmental factors. As they're going about their daily lives there's things that happen that put them at higher risk of forming blood clots regardless of what their genetic predisposition is.”

What environmental factors can lead to DVTs or PEs?

Dr. Swanda: “And what are some of those environmental factors that could predispose someone to these conditions?”

Dr. Weinberg: “One of the main common ones is immobility. If you're not moving around very much, if you're bed bound, if you're laying around in bed, that puts you at much higher risk of forming blood clots in your legs. And, the reason for that is anytime you're not moving your legs blood tends to pool in those blood vessels. And when blood isn't circulating clots tend to form. One of the common causes of blood clots is someone who had recent surgery, or maybe they were hospitalized for a medical condition, or maybe they were just very sick at home with the flu and they were laying in bed for three days. Anytime you're not moving around a lot that puts you at high risk. In fact over 50 percent of these blood clots end up happening either during hospitalization or shortly after hospitalization for that very reason. So periods of immobilization can increase your risk. You may have heard of long travel. If you've had extended travel where you're on an airplane for 14 hours and you're not moving about the cabin and walking around, that can put you at higher risk for the same reason. There are certain infections that can put you at higher risk because they're pro-inflammatory that cause inflammation in the body and that then leads to blood clotting as a response to that inflammation. One of the common infections that we've all heard of is Covid-19. We've seen a higher association with DVT's and PE's in those patients that have Covid-19. Interestingly pregnancy, pregnancy is a common thing and it puts you five times higher likelihood of forming a blood clot while you're pregnant. And that risk actually can last up to even three months after delivery. So we always ask our pregnant patients “are they having any signs or symptoms of this condition?”. Some other common ones are cancer. Cancer is a pro-thrombotic condition. It makes you at a higher risk of forming blood clots. Certain medications such as estrogen therapies. Whether it's hormone replacement therapy or even oral contraceptives that are estrogen based can put you at higher risk. And then another big one that impacts unfortunately a large percentage of our population are those that are overweight or obese. And the reason for that is kind of interesting. It is not just because people who are less well-conditioned don't move around as much, which is one of the earlier reasons I gave - immobility. But interestingly enough when we're overweight or when we're obese we have more adipose cells, more fat cells. And adipose tissue produces estrogen. High levels of estrogen in our body. And like I mentioned with the oral contraceptives a minute ago. Higher levels of circulating estrogen actually put you at higher risk of blood clotting. So that's one of the reasons why people who are overweight are also at increased risk.”

Signs and symptoms of DVT and PE

Dr. Swanda: “What are some things that everyone can be on the lookout for related to signs and symptoms of DVT and PE so they can hopefully try to get treatment before they end up having some serious consequences?”

Dr. Weinberg: “Yeah awareness is key. You hit the nail on the head. And, it is important to know both the signs and symptoms of deep vein thrombosis, DVT, as well as pulmonary embolism, or PE. Sometimes people can pick up the DVT early on and they may realize that they have some leg swelling. They may have some redness in their leg or some pain in their leg. That may be an early sign. However sometimes they never realize that they had a DVT and their first manifestation of symptoms is actually a pulmonary embolism. Some of the symptoms of pulmonary embolism (PE) to be aware of are chest pains and sometimes that chest pain is worse when you take a deep breath or when you're coughing. Patients will a lot of times have shortness of breath. Activities that usually they didn't think much of all of a sudden they feel more winded when they do them. They may experience a fast or irregular heartbeat or palpitations, we sometimes call it irregular sensations in the chest. Sometimes people can even present with back pain because remember your lungs are both at the front of your chest as well as in the back. So, sometimes people will feel a little pain towards the back of their chest area. Although it's more rare, occasionally patients will cough up blood. And then another telltale sign is vital sign changes. So you may notice that you have all of a sudden low blood pressure, or you may feel dizzy, or you may even pass out. Those could be signs that you may have a pulmonary embolism (PE) and it's worth getting checked out at that point.”

DVT treatments

Dr. Swanda: “Then what do the treatments actually look like for somebody who comes in and they are confirmed to be having DVT? Is there anything available for that individual?”

Dr. Weinberg: “The treatments are very effective once we recognize what's going on. And the mainstay treatments are anticoagulants or blood thinners. And you may have heard of some of them on the market: Coumadin(Warfarin). There's also some of these newer drugs such as Xarelto or Eliquis which you may have seen on the market. And they work a little bit differently but essentially at the end of the day they thin your blood and they stabilize the clot. So what they do is they thin your blood so you don't form more clots and then they stabilize the clot that you currently have and allow your body the time it needs to break it down. So, it's interesting they don't actually break down the clots but they stabilize the clot and it's your body's own mechanisms that help break down that clot over time. And then in the meantime the blood thinners prevent the clot in the legs from breaking off and forming more potentially deadly pulmonary embolisms.

Those that have more severe deep vein thrombosis (DVT) they're at higher risk of worse outcomes from pulmonary embolism (PE): if they present let's say with low blood pressure or very symptomatic, there are certain things that can be done in addition to those blood thinners and to more urgently intervene. Some of those include a medication called TPA which is a clot busting medication. So, that medication actually goes in and tries to break up the clots quickly. There is an increased risk of bleeding with that medication so we don't use that with every patient but for the right patients we may choose to use that if it's a more severe situation. There's also devices where you can actually go in and break up the clot or extract the clot so it's really tailored to the particular case and situation. But, there are additional techniques we could use.”

Dr. Swanda: “What's something people should take away from this discussion about DVT and PE?”

Dr. Weinberg: “DVT and PE are common, deadly, and can impact potentially everyone. Knowing the signs, symptoms and potential risk factors will lead to better identification and treatment which can be life saving for you, family, and friends.”

Checkout the full conversation posted on November 30, 2022.

Rob Swanda, PhD is an mRNA biochemist and science communicator who obtained his PhD from Cornell University in 2021. Follow Rob Swanda, PhD on Twitter: @ScientistSwanda

Dr. Aaron Weinberg is the national director of clinical research at Carbon Health with a background in pulmonary critical care and internal medicine. Follow Dr. Aaron Weinberg on Twitter: @AaronWeinbergMD

Carbon Health Editorial Team

The Carbon Health Editorial Team is a group of writers, content creators, and thought leaders who are here to empower you to take charge of your health.