In part one of a two-part interview, DocWire News partner Hady Lichaa, MD, FACC, FSCAI, FSVM, RPVI, sits down with Vladimir Lakhter, DO, to discuss the topic of chronic thromboembolic pulmonary hypertension (CTEPH) interventions, a burgeoning field in cardiovascular medicine.
Dr. Hady Lichaa: Hello. This is Hady Lichaa with DocWire News. I have the pleasure of having Dr. Vladimir Lakhter with me. He is an expert on chronic thromboembolic pulmonary hypertension interventions. And we’re going to be having a talk about this field of cardiovascular medicine that’s growing. Welcome, Dr. Lakhter.
Dr. Vladimir Lakhter: Thank you so much, Dr. Lichaa. Thank you for having me. It’s a true pleasure to be here.
Dr. Hady Lichaa: I am thrilled to talk about this with you. And first of all, tell us a little bit about yourself. Where do you practice now, and how did you get introduced into the thromboembolic world?
Dr. Vladimir Lakhter: Sure, thank you. Yeah, so my name is Vlad Lakhter. I’m an interventional cardiologist and endovascular specialist at the Temple University Hospital in Philadelphia where I’ve done most of my training. And early on in my career, as a trainee, was lucky enough to meet my mentor, Dr. Riyaz Bashir, who’s been doing venous work for many years prior to me even joining the center, and has actually started doing balloon pulmonary angioplasties several years before I started as a fellow in cardiology at Temple. So because he was my mentor and we were doing a lot of research together and I had an interest in vascular medicine, I ultimately got involved in doing balloon pulmonary angioplasties for patients with chronic thromboembolic disease fairly early on as a general fellow, an interventional fellow. And then continued doing that in my endovascular year at Mass General with Ken Rosenfield. And then came back to Temple and have been doing interventional cardiology, vascular medicine, but also quite a bit of chronic thrombolic work. And mostly balloon pulmonary angioplasty sign and pulmonary angiography for patients with CTEPH.
Dr. Hady Lichaa: Excellent. Thank you. So, let’s start with the definition of CTEPH. What is CTEPH defined as, and what does it stand for?
Dr. Vladimir Lakhter: So I think the way I think of CTEPH is a patient who sustained a venous thromboembolic event, pulmonary embolism of an acute nature, and was then treated with proper anticoagulation for at least three months, but continue to have symptoms after treatment. Usually, those symptoms are dyspnea, poor exercise tolerance. A lot of these patients will have some degree of right ventricular dysfunction, and by definition, they have to have pulmonary hypertension. And also, you have to establish the fact that they have chronic thromboembolism. And the best gold standard for establishing that diagnosis is a profusion defect that’s unmatched on a VQ scan.
So, putting it all together, somebody who had an acute PE and after three months of anticoagulation has persistent mismatch on a VQ scan and has evidence of pulmonary hypertension echocardiography and is symptomatic. So those are-
Dr. Hady Lichaa: So every single patient gets an echocardiogram, a CT scan of the chest with IV contrast. Obviously, if they can from a renal perspective, VQ scan, and sometimes a CPET. A cardiopulmonary exercise tests. Is that part of the mandatory workup?
Dr. Vladimir Lakhter: So, I think a lot of the patients that come to our center who have already been evaluated by their local either cardiologists or a pulmonary physician, a lot of those patients would have had CT angiograms and VQ scans. Sometimes even right heart catheterizations. I think in thinking about whether a patient has CTEPH, generally I’d get an echocardiogram and the VQ scan. And then ultimately, if there are findings of CTEPH on those two studies, then I would consider getting a CT angiogram to really define the extent of it and prove that there is a webbing or occlusion of pulmonary arteries and figure out how proximal the disease is to determine whether the patient has surgical disease and they’re a surgical candidate. But definitely a VQ can and echocardiogram in everybody who had a prior history of pulmonary embolism.
And the timing of that is variable, and you’ll see that being done after three months after acute event, and some centers will do it after six months. So somewhere between three and six months, especially in patients that are persistently symptomatic of any kind; either have poor functional capacity, decreased exercise tolerance or are very dyspneic persistently after three months, I would get at least an echocardiogram and a VQ scan. Probably follow up with a CT scan down the line.
Dr. Hady Lichaa: And the definition of pulmonary hypertension. Could you update the audience on that?
Dr. Vladimir Lakhter: So actually, the way it always used to be up to recently is that basically pulmonary hypertension is any mean pulmonary artery pressure over 25 millimeters of mercury. But more recently, I think the guidelines, especially the pulmonary hypertension specific guidelines, suggest that maybe we should be thinking about pulmonary hypertension in anybody who has a mean pulmonary artery pressure over 20 millimeters of mercury. So anywhere between 20 and 25, but definitely over 25 is pulmonary hypertension.
Dr. Hady Lichaa: So that’s a substantial difference. Between 20 and 25, you’re talking about at least 20% more patients. There are a lot of patients that qualify for that. So even the soft mean pressure of 23 is still abnormal. Now, I had the pleasure and the honor to visit your center, and I obviously saw how much of a well-oiled machine you guys have at Temple. Talk to us about the pulmonary angiography specifically. And I know you’re a world expert on that. You’ve given multiple talks on it. So obviously in summary, obviously we can go through the technical specifics, but in your opinion, pulmonary angiogram has to be done at a center of excellence? Is that correct? Or in experienced hands?
Dr. Vladimir Lakhter: Yeah, I think so. We definitely have referrals that come through to our center, and sometimes patients will already have had a pulmonary angiogram. And definitely there are times that the pulmonary angiography is excellent. There’s a lot of variability I find between the techniques that are employed for pulmonary angiography and depending on what the patient’s ultimate outcome is going to be, sometimes we have to repeat those pulmonary angiograms. For example, our surgeon, he’s a world expert surgeon, Dr. Toyoda, he really likes to have a pulmonary angiography done in two views; AP and lateral. And I think that really helps him define the surgical planes and plan out the pulmonary thrombectomies that he will ultimately have to perform.
But depending on the operator and depending on the center, you may or may not get the same angulation. And so I find that pulmonary angiography really tends to be center specific. We tend to repeat quite a bit of our own pulmonary angiograms, specifically for planning of surgeries or planning of balloon pulmonary angioplasties, so that we can make a plan based on that.
I think pulmonary angiography is done as a later on test. It’s not something that patients will get upfront. And some patients don’t really need a pulmonary angiogram if there is very clear evidence of proximal chronic thrombolic disease on CT angiography. And if the surgeon is happy with the quality of a CT angiogram and they can really plan out their surgery based on the CT angiogram, then we’re not called upon to do the pulmonary angiogram. But a lot of times, I think there is a question of, “Okay, we’re seeing something on the CT scan. We’re not quite sure if that’s a web or if that’s an artifact related to a flow of contrast or timing.” And in those cases, we will perform pulmonary angiograms. So, I think in the majority of cases, we do it. And I think that that really helps us and the surgeon decide if the patient has surgical disease. If so, they should go for surgery. And if they don’t have surgical disease, or if they’re not a good surgical candidate, then we can use the pulmonary angiography to plan out balloon pulmonary angioplasty, if that’s the way the treatment team decides the patient should be treated with.
Dr. Hady Lichaa: Excellent. So now we have a pulmonary angiogram, which is a detailed study, very well performed. Which kind of patients are the patients that you think are good candidates for balloon pulmonary angioplasty, or BPA?
Dr. Vladimir Lakhter: Yeah, that’s a great question. I think one thing to point out as probably one of the most important things is that most patients with chronic thromboembolic pulmonary hypertension should undergo surgery if they’re surgical candidates. I think that’s the main thing. When we’re getting these patients for an evaluation, we’re really trying to decide, is this patient a surgical candidate? Because surgical pulmonary thrombectomy is really the gold standard for treatment of patients with CTEPH, and an expert surgeon can really cure the patient of chronic thrombolic pulmonary hypertension. And we’ve had really incredible results with patients who have undergone surgery at our center.
Now, there’s going to be a couple of groups of patients that will ultimately either not get surgery because they’re a poor surgical candidate due to comorbidities, or they’re a poor surgical candidate due to the fact that the disease is very distal, and the surgeon may not feel that they can get really to the subsegmental level, the type four disease. Or some patients really don’t want surgery, even if they are surgical candidates. So that’s one group. And another group are those patients that have undergone pulmonary thrombectomy but have residual pulmonary hypertension after surgery. And that percentage of patients could be anywhere from 20 to 30%.
So I would say that the majority of patients that we do BPA on are those who are nonsurgical candidates and have not undergone surgery in the past. And I would say that about maybe 10 to 20% of all patients that we do balloon pulmonary angioplasties on are those patients that have residual CTEPH after surgery. And really in thinking of how is that possible, the surgeon may be able to get the very proximal disease, but again, if there’s a very diffused distal disease and some of that disease is not able to be removed surgically, even though you may have a substantial hemodynamic improvement, you may still have some residual pH from those distal lesions. And that’s something that we can approach with BPA.
Dr. Hady Lichaa: Excellent. And you mentioned stage four disease or level four disease. Could you elaborate on this classification? What’s one, two, three and four?
Dr. Vladimir Lakhter: Yeah, sure. Of course. So level one disease is main pulmonary artery disease. So if you have a main pulmonary artery occlusion, right main pulmonary artery or left main pulmonary artery, that’s as proximal as it gets, effectively, except if the patient had a complete total pulmonary artery trunk occlusion, which is not really compatible with life. So the patients that have CTEPH, the most proximal disease is level one disease, occlusion of the main pulmonary artery. And as you move out distally from the main pulmonary artery, you get level two, three and four diseases. So level two disease would be occlusion of the intralobar artery, or stenosis of the intralobar artery. So you don’t necessarily have to have a complete occlusion, but you may have thrombus, the chronic clot that extends, and the clot starts at the level of the intralobar artery and then most commonly involves segmental and subsegmental branches. It’s usually not just limited to the intralobar. Level three disease would be main pulmonary artery and intralobar pulmonary artery that’s free of clot, but the disease starts at the segmental level. And level four is basically everything else; subsegmental disease, sub-subsegmental disease.