Updated: Mar 16
Many patients suffer from chronic deep venous thrombosis (DVT) and post thrombotic syndrome as a result of delayed intervention. A DVT can present in many ways with patients experiencing a variety of differing symptoms. Vascular surgeons Dr. David Dexter and Dr. Steven Abramowitz discuss standardized ways of evaluating DVT with clinical scoring, IVUS imaging, and pre-DVT history assessment. They also provide general guidelines for choosing the appropriate catheter-based intervention for treatment.
We’ve provided the highlight reel below, but you can listen to the full podcast here.
The BackTable Brief
Many patients suffer from the sequalae of acute DVT, developing chronic symptoms that are left untreated. Dr. Abramowitz and Dr. Dexter discuss the need to target intervention at the acute DVT stage. For Dr. Dexter’s practice, the referral pathway for a DVT patient is usually initiated after the first visit with a family medicine doctor, urgent care, or ER.
DVT patients vary in their clinical presentation. However, it is important to adopt a method for standardizing DVT evaluation with a Villalta or Venous Clinical Severity Score (VCSS), according to Dr. Abramowitz. When assessing DVT patients, it is also important to know how well anticoagulation will be tolerated, the degree of mobility post-procedure, and why the DVT developed in the first place, says Dr. Dexter.
Most DVT interventions can be completed while the patient is awake under moderate sedation in the lab, according to Dr. Dexter. For catheter-directed thrombolysis, Dr. Abramowitz recommends the popliteal or posterior tibial veins as access sites. For mechanical thrombectomy devices, he suggests access through the internal jugular or popliteal veins. Both Dr. Dexter and Dr. Abramowitz use intravascular ultrasound (IVUS) 100% of the time to accurately visualize the thrombus, its morphology, and any external compression or venous wall scarring.
When selecting the appropriate catheter-based intervention for DVT, Dr. Dexter sizes the endovascular device to the specific vessel being treated. Dr. Abramowitz considers the chronicity of the clot to help guide treatment and accounts for risks such as hemolysis and acute kidney injury, potential for scarring, and blood loss.
Disclaimer: The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
Who Needs DVT Treatment?
Dr. Abramowitz and Dr. Dexter discuss the different patient populations that can present with DVT, including young and healthy hypercoagulable individuals, oncology patients, previous IVC filter recipients, patients with prolonged hospitalizations, and those with recent orthopedic surgery. Many patients have already developed post-thrombotic syndrome and present with chronic vein obstruction by the time they are referred to an interventional specialist. Therefore, Both Dr. Abramowitz and Dr. Dexter emphasize the importance of intervening at the stage of acute DVT.
Can you kind of describe the ideal patient who you think is going to benefit from DVT treatment? Can you kind of describe what that patient might look like?
The ideal patient is the young, healthy individual, male or female, who probably is hypercoagulable and had their first episode of deep vein thrombosis, usually surrounding a flight or sometimes an anatomic compression like a May-Thurner lesion. They are mobile, healthy in shape, no contraindications to anticoagulation. Usually, they're young in their 20s or 30s. With a proximal DVT, treating them is going to give them symptomatic relief and also prevent post-thrombotic syndrome down the line, especially because they're at high risk for having a recurrent thromboembolic event as a result of their hypercoagulable state.
What would be the ideal time frame in which you would be able to see this patient and intervene?
As soon as possible. In reality, usually by the time these patients end up in the emergency room, when they are swollen and heavy, symptomatic for a few days. It's very rare that someone wakes up that morning and drags himself to the doctor's office. Most of the time when you're interacting with patients, even if they've only been symptomatic for a few days, the clot we're dealing with is probably a week to a week and a half old.
Can you describe someone who's maybe a more typical patient that you're used to seeing in your clinic?
The more regular people are those that had an IVC filter placed some number of years ago, and it was forgotten about or it was permanent. We have a catastrophe with the number of permanent TRAPEASE filters that got placed and left in very young otherwise healthy, usually women for some reason that have now gone on thrombosis through IVC both iliac veins.
Taking a step back again from that ideal patient and really focusing on that 50% of the patient population with something else going on in their health that caused them to develop a clot—for the most part, we're seeing oncology patients coming in with lower extremity DVT. They either have or do not have metastatic disease, and those patients are really not good lytic candidates. Otherwise, we're seeing patients who are already hospitalized, who either had prolonged hospitalizations or had orthopedic surgery with proximal DVT. And then the last are those people coming into the ER with some hypercoagulable state or something with their first or other recurrent DVT state.
There are many patients who had a prior DVT, and they didn't know where to get help from. They got put on anticoagulation for three months, six months, depending on what protocol they were following, and they were out in the wilderness. They were doing okay, and they didn't realize that the heavy, achy, throbbing leg they were dealing with for ages is treatable. They also didn't know that they could have a new acute event on top of their chronic obstruction.
There's a very big patient population in most communities and most major metropolitan areas of untreated, post-traumatic patients who are suffering from the sequelae of acute DVT long term. Post-thrombotic syndrome is the long-term impact on the vein, and its ability to carry blood in a low pressure and low flow state. Once the vein is scarred and has changed that compliance from the inflammatory process that is instigated to deal with deep vein thrombosis, and you're behind the eight ball. We really need to target those patients that present with acute DVT in the emergency room, in urgent care centers, in the outpatient, or inpatient setting. There's a huge opportunity for us to prevent that disease process from progressing by intervening on the acute stage, which is deep vein thrombosis.
Steve said it exactly right. The right patients don't come at the right time and the wrong patients come at the wrong time, really. When I started in practice, the first system wide initiative that I took on was to start an algorithm and a treatment paradigm for acute DVT. Our acute DVT pathway starts when any patient shows up either to one of our family practice doctors in our multi-specialty group, one of our urgent cares, or one of our ERs. We've integrated this algorithm into the electronic medical record. So, once patients are divided up into high risk or low risk categories, we determine who should go home, who should be admitted to the hospital, and who should see an interventionalist early.
How To Clinically Assess DVT Patients
Clinical presentation of DVT can vary widely. However, Dr. Abramowitz recommends picking a method to help standardize the clinical evaluation such as assigning a Villalta score or Venous Clinical Severity Score (VCSS). When evaluating DVT patients in the ER, Dr. Dexter conducts a bleeding assessment to understand how the patient will tolerate anticoagulation. He also gauges patient mobility post-intervention and obtains the pre-DVT history including previous surgeries, prior instances of DVT, and family history.
Can you talk a little bit about when a patient first appears in your clinic? What does your evaluation look like in terms of what are the most important things you need to know, what are of the most important things about your physical exam?
I think one of the most fascinating things about DVT as a disease process is how variable people and patients experience their symptoms. I have patients who will come in with DVT, extending from the common iliac vein all the way down to the tibials. They'll have minor swelling and say that they are not in a significant amount of pain. I'll have the patient come in with very isolated tibial DVT and writhing in discomfort with extreme swelling and tenderness on dorsiflexion of the foot. So, a lot of it is about finding a way to approach the patients that it's standardized to you. In our clinic, we tend to use the Villalta score. There are a variety of different scoring systems out there, but I think having a standardized way of approaching how you're assessing the symptoms of the patient is really key both in managing patient expectations for recovery and understanding how to expand whatever therapy you choose. You have to have a way to follow them and a lot of that has to do with some scoring system that is both objective and subjective. Also important is coming up with an algorithm for imaging to determine the extent of the disease because a lot of times it's the extent of the thrombus burden that's going to guide you in terms of what you recommend to the patient. So, it can be either a duplex or coaxial imaging.
When somebody comes to the ER, and we've now made the decision that they need to have their DVT treated, I think there's some very specific things that I'm interested in to make sure that I know that what I'm going to do is going to work and is going to be safe. The first thing that I do is a true bleeding assessment. It’s important to understand how the patient's going to tolerate anticoagulation and how they're going to tolerate a thrombolytic agent if we plan on giving one. We do a stroke check and talk about cancer, whether they've had metastatic disease. At that point, some people may get a head CT scan before we go along and offer them an intervention. Sometimes we don't depend on what cancer they may have, and if they've had brain mets or at least at risk of brain mets. The second question that I always ask them is about their mobility. When we talk about all the scoring systems for how active and mobile they are, it really doesn't matter how mobile they are now that they have the clots, but it’s important that I look at how mobile they're going to be. The more they walk, the more they're going to help themselves. And then the third question that I always try to dive into is the prehistory and understanding why the DVT developed. So, very often the risks of re-thrombosis are identifiable on a thorough questionnaire of prior history of DVT, prior family history of clotting conditions, and prior surgical interventions that may have interrupted the venous system. It's amazing how many times in the past eight years I found someone who's had a central venous injury where something was ligated, sutured, or bladed, and the patient was just completely unaware.
That's an interesting point. Are there some common surgeries that you've seen as repeat offenders in terms of things that potentially result in some venous injuries?
During a total hip or during a spine operation, the iliac veins are usually mobilized and sometimes you can just induce a DVT from that, but venous injuries during anterior exposures to the lumbar spine are certainly a well described complication. If you can't repair them, they do get ligated from time to time. Sometimes we don't pay as much attention to retroperitoneal strippings. When someone has lymph nodes taken off the iliac vasculature, it's very common that the iliac veins get beat up. They can clot either acutely or they can become fibrotic from scar tissue later. These are common surgeries that I look at and ask about.
Clinical Setting, Access Site, & Imaging When Initiating DVT Treatment
Most DVT interventions can be completed without general anesthesia and in the lab, according to Dr. Dexter. For catheter-directed thrombolysis, Dr. Abramowitz recommends the popliteal or posterior tibial veins as access sites. For mechanical thrombectomy devices, he suggests access through the internal jugular or popliteal veins. Both Dr. Dexter and Dr. Abramowitz use intravascular ultrasound (IVUS) 100% of time to accurately visualize the thrombus, its morphology, and any external compression or venous wall scarring.
For the most part, DVT intervention can be done awake with good moderate sedation in the prone position in the lab. I very rarely find the need to do a DVT case in the hybrid OR, unless I'm using the AngioVac, where I'm trying to really move large burden clot out of the IVC, both iliacs, both femoral. Those people I do under general anesthesia in the hybrid OR with perfusion, but pretty much everybody else is in the lab.
Can you talk about the procedure components, where you treat these patients and maybe potential access sites, and how you're going to initiate the procedure?
I think that there's a lot of debate as to access site selection. One of the key things is whether or not you fall into the camp that every single inflow vessel needs to be treated or that you need to treat the major inflow vessel (the femoral-popliteal segment to the common term role or the external iliac). For the most part, I would recommend your access site being either the popliteal vein or the small saphenous vein. If you buy into treating the tibial inflow vessels, I would use the posterior tibial vein as an access site because really, if you're doing catheter-directed thrombolysis, that's going to give you the maximum kind of bang for your buck in terms of clot exposure to the TPA. I would really focus in on the popliteal vein or the posterior tibial vein if you're doing catheter-directed thrombolysis. Most of the mechanical thrombectomy devices aren't going to be supported by tibial veins so if you're really focusing on mechanical thrombectomy, such as using the MRI device or Penumbra device, then you can focus more on the internal jugular or the popliteal. If you enter into the common femoral vein, you really are running a risk of missing a lot of that proximal DVT.
I think again, Steven said it right. You want to expose as much of the clot to therapy as you possibly can.
What percentage of your cases are you using IVUS?
100%. It's really surprising the number of cases you do where you do a CT venogram and you think "Wow, that vein looks great." You throw an intravascular ultrasound catheter in there, and you say "Geez, that's got 30% circumferential or partial thrombosis of the vein." So, I think that without intravascular ultrasound, you are really under assessing the extent of disease and the potential anatomic compressive lesion that may be leading to the disease.
The imaging provided by intravascular ultrasound can tell us what the clot morphology looks like. It could show us scarring on the wall, it can show us external compression. You don't know what you're not treating until you look. If you're not operating with IVUS when you're doing a DVT case, you're breaching the standard of care I would think in 2020.
Choosing the Appropriate Mechanical Device for Any DVT Scenario
Different patients and DVT scenarios require different treatments. Dr. Dexter sizes the endovascular device to the specific vessel being treated. Dr. Abramowitz considers the chronicity of the clot to help guide treatment and takes into account the potential risks associated with each device, including risk of hemolysis and acute kidney injury, potential for scarring, and blood loss.
…Do you guys have any potential tips, go-to devices, or techniques that you like [for treating DVT]?
The timeframe of the clot is really key. There are plenty of patients who come in with a delayed fragmentation. For patients who are coming in and who have a contraindication to lytic therapy, for the most part, the chronicity becomes a little bit important. There's that sort of collagen base layer that gets deposited in the clot or that transitions to the clot, starting around day four to five. Really once that collagen starts to organize a matrix within the clot burden, it becomes a lot more challenging to mobilize with a device that's purely suction based. That's where I start thinking about using something like the Inari ClotTriever or the Inari FlowTriever that gets in the IVC… Where I'm thinking about Penumbra, then I have to say, "Well, what am I going to do to break up some of these collagen-based tendrils or tethering pieces that are going to keep that clot attached to the vein wall and organized amongst itself?” Sometimes you'll have to macerate using a balloon. For patients who are presenting in the more acute phase, less than two weeks, if I'm going to use a catheter for thrombolysis, I can see how the clot responds. I can use intravascular ultrasound again to see if there's any scarring or residual clot burden that has different ages. Then, I target that specifically using mechanical thrombectomy or some sort of second thrombectomy device.
I try to size the device to the clot that I'm removing. The first true mechanical device I was exposed to was the AngioVac by AngioDynamics. I still use it on average once a month for complete occlusions of the IVC. I have tinkered with using the FlowTriever device in combination sometimes with ClotTriever to pull out clots from both iliacs and the IVC. I have certainly done some successful cases with the 8 French Penumbra catheter and the CAT8, but neither of those devices are really purpose built for the IVC. Fortunately, both those companies have up and coming new toys coming that are meant to tackle IVC and IVC filter thrombosis. Knowing the average iliac vein is about 16 millimeters, I've used both the Penumbra device mechanically and the Inari ClotTriever device to clear out an acute or a subacute iliac. I've certainly found the Inari device can pull out very, very age-old things which has surprised me given how soft the coring element truly is. I've not seen a lot of venous wall damage from it, but knowing it goes to 16 millimeters for an average 16-millimeter iliac vein, that's probably my go-to device there. If I am going to pull out something isolated in the fem-pop segment, I'm probably going to select the 8 French Penumbra, and stick the small saphenous vein.
The other thing I would take in consideration are some of the consequences of each device. You may have a patient who already has acute kidney injury or chronic kidney disease, and you may not want to deal with the potential issues of hemolysis or acute kidney injury as a result of the hemolysis caused by the agitation from AngioJet. If you have a patient who has a really scarred femoral-popliteal segment that has had DVT in the past and this is their second session, you may not want to use the ClotTriever device. The sheath size and the potential need for having to go back to the venous system down the line may cause scarring. So, in that instance, you may want to switch to the AngioJet. Then, there is blood loss to consider. Right now, there's no way to reintroduce some of the aspirated material that you take out with, let's say, a Penumbra or a ClotTriever or FlowTriever device. If you have a chronically ill patient who's been hospitalized, who is anemic, or just had a major surgery of blood loss, you may not want to aspirate four to six of those large syringes of blood with an inability to give it back. The great thing about having all these tools now is that you really get to think about each patient, what their diseases and what their comorbidities are, and come up with the best device for them.
Dr. David Dexter is a practicing vascular surgeon with Sentar Vascular Specialists in Virginia.
Dr. Steven Abramowitz is a practicing vascular surgeon at MedStar Georgetown University Hospital in Washington, D.C.
Host Dr. Christopher Beck is a practicing interventional radiologist with Regional Radiology Group in New Orleans, LA.
Cite this podcast:
BackTable, LLC (Producer). (2020, March 25). Ep 59 – Endovascular Treatment of DVT [Audio podcast]. Retrieved from https://www.backtable.com/podcasts
The Materials available on the BackTable Blog are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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