Feb 17, 2017
Dr. Zamanian is the Director of the Adult Pulmonary Hypertension (PH) Program at Stanford University Medical Center. He currently directs the Vera Moulton Wall Center clinical database and biobank and focuses his research on clinical characterization and impact of novel risk factors such as methamphetamine use, and biomarkers, such as insulin resistance, in pulmonary arterial hypertension. Beyond industry clinical trials and registries, Dr. Zamanian has re-focused the research mission of the Stanford PH program by collaborating with basic science faculty and implementing several proof-of-concept and phase II clinical trials of novel therapeutics developed at Stanford University. Dr. Zamanian also serves on phaware’s Medical Advisory Board.
My name is Roham Zamanian. I'm the Director of the Adult Program at Stanford University Medical Center, the Adult Pulmonary Hypertension program.
CTEPH refers to chronic thromboembolism as a cause of the pulmonary hypertension. It's often a very strong mechanical obstruction that when surgically approachable, it's completely curative. The difference between PAH and CTEPH is that while the vascular changes may occur that are similar between the two diseases, CTEPH has to be seen as primarily a vascular obstruction from a clot or organized clot, and the first steps should always be consideration of surgical removal of that clot. That's how it's different than PAH, because, PAH ends up being a very definitive vascular disease. There are no surgical options currently for PAH that has to do with the removal of the neointima that's formed. Really, that's why it's a medical therapeutic approach in PAH.
I think that once you recognize the pathobiology of the two and how they are similar and different at the same time, you recognize that again, the first and foremost important thing that you have to think about is if this chronic thromboembolic PH patient, do they have the option of surgery or not? The workup of patient with CTEPH begins in a very similar pattern with a screening echocardiogram as we do for PAH, but very quickly, we must do a nuclear evaluation to see if there is clot disease and if there is clot, then what I've learned is that there must be angiographic determination of the extent of the blood clot. You will be doing pulmonary angiography during the right heart catheterization. Sometimes even advanced nuclear and MRI technologies to determine sort of the mapping of the clot and if it could be approached surgically. Then, soon after, it's determining whether medical therapy should be added before surgical evaluation takes place. That's the general approach to a CTEPH patient.
A PTE surgery is pulmonary thromboendarterectomy. It's an open-heart bypass surgery on-pump, where the surgeon goes into the lung, into the blood vessels of the lung, dissects very carefully around layers of the blood vessel and into the blood clot, and tries to scoop and scoops that blood clot, a chronic clot, an organized clot, and webs, and all these things that happen with chronic blood clots, out of the lung so that there is flow of blood passed the areas of blood clot. That is what a PTE is.
Up to now, the exchange of information, the discussions around the care of the patients with chronic thromboembolism and pulmonary hypertension has taken place in small forums, small journals, and publications, but when we come together in a forum like this, we ask questions that you might think are not important, but become super important if you make connections, you learn from each other, you learn from latest practice guidelines, you learn from experts in the world that you don't have contact with every day. That's really what's important about the nurses also recognize the collaborative nature of this rare disease community to begin with, and that's not something that you could get when you're sitting all alone in your office trying to read a publication. I think that's why conferences like this are super important and very helpful for both physicians and practitioners.
It used to be fairly rare, maybe 2 to 3% of our PH evaluations were for CTEPH. Over the last three or four years, we've had a tremendous increase in the number of patients that are referred to us. We're at about probably one or two patients per month even, which is a huge increase for us. I think that there are general educational programs that are taking place. The physicians are reading the publications that are coming out more about chronic thromboembolic disease and pulmonary hypertension, to realizing that acute pulmonary embolism can lead to chronic disease in a certain number of cases. We've had a tremendous increase and I think that that's why it's important for me and my team, who are here, and some of our advanced practitioners to be here, to learn more about this disease and the potential therapies.
I think that it's very complicated data, as already shown now, that the time to diagnosis for CTEPH is similar to PAH in the order of 18 to 24 months. It's very, very sad. I think that the other issues specifically around thromboembolism is that maybe there are times that a physician treats a patient with what they think is an acute pulmonary embolism but never works it up and follows it up to see. I think that data will come out more, but I think it's generally similar, unfortunately, to PAH.
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