Jan 25, 2019
Dr. Marc de Perrot joined the Division of Thoracic Surgery as a staff surgeon and Assistant Professor at the University of Toronto in 2005. In 2009, he was appointed Associate Professor of Surgery based on his research and clinical work. Dr. de Perrot’s surgical expertise focuses on surgery for end-stage lung diseases such as lung and heart-lung transplantation as well as pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension. He is also the Head of the Toronto Mesothelioma Program and is involved in basic science research, new treatment with immunotherapy and combined modality therapy. In this episode, Dr. de Perrot discusses the importance of early diagnosis.
I'm Marc de Perrot, I'm a thoracic surgeon at the Toronto General Hospital. I'm in charge of the chronic thromboembolic pulmonary hypertension activity, at the Toronto General Hospital, University Health Network. I'm a thoracic surgeon performing pulmonary thromboendarterectomy as a treatment for chronic thromboembolic pulmonary hypertension, or CTEPH.
I've been working in the field of pulmonary hypertension for almost 20 years. I initially started working in the context of pulmonary hypertension as a lung transplant surgeon; that's how I got involved with PH. Then we were seeing some patients with chronic thromboembolic pulmonary hypertension [who were] referred for lung transplantation. The surgery of pulmonary thromboendarterectomy has improved in success. Eventually, it was becoming the treatment of choice. That's how I got involved more directly in CTEPH.
The pulmonary endarterectomy is a curative treatment CTEPH. It was a much better option than the lung transplantation, which has some difficulty and some limitation in the long term. So the pulmonary endarterectomy, or thromboendarterectomy, was clearly a much better option for patients with CTEPH. It was important that the patients were referred for the right surgery. That's how I started the pulmonary thromboendarterectomy program at the Toronto General Hospital, back in 2005.
The meaning of chronic thromboembolic pulmonary hypertension, or CTEPH is two things: one is the pulmonary hypertension, and the cause of pulmonary hypertension is chronic thromboembolic disease. So these are patients who have a history of pulmonary emboli. The emboli leads to scarring of the vessel of the lung, which eventually leads to the pulmonary hypertension. So it's really the combination of the pulmonary emboli and the development of pulmonary hypertension that leads to the diagnosis.
The important part is that chronic thromboembolic pulmonary hypertension, or CTEPH, is the only curative form of pulmonary hypertension. Therefore it is critical that it is diagnosed properly in order to give a chance of cure to patients with PH, which they might not have otherwise.
CTEPH, like any form of pulmonary hypertension, the symptoms are not very specific. So the main symptoms is shortness of breath, or dyspnea. Patients feel short of breath going up a flight of stairs. A lot of the time, they will attribute that to some deconditioning, or getting older. So to make the diagnosis of CTEPH sometimes takes a long time. It can take about a year for [the eventual] diagnosis to be made. That is similar to pulmonary hypertension in the sense the symptoms are very non-specific and very similar. The difference in CTEPH compared to other patients with PH is that CTEPH patients typically are in their 50s, 60s or 70 years old, or sometimes 80 years old [when they] develop the disease.
So it's a condition that tends to be developing later on in
life, in contrast to pulmonary arterial hypertension, which can
occur more frequently in younger patients. So, a lot of the time
the symptoms are quite similar to patients with emphysema, COPD,
pulmonary fibrosis, so the differential diagnosis of CTEPH doesn't
necessarily come up at the top of the list. It does take some time
for the patient to be diagnosed, occasionally.
On the other hand, once anybody who has a diagnosis of pulmonary hypertension needs to be evaluated for CTEPH, in order to ensure that the diagnosis of CTEPH is made if pulmonary hypertension is diagnosed. Again, since this is the only form of PH that is potentially curative.
The symptoms of shortness of breath is very non-specific, and a lot of the time shortness of breath leads to evaluation of the lungs. So the lung is looked at very carefully, but the vessel of the lungs takes extra investigation in order to be evaluated. So unless we evaluate the vasculature of the lungs, you may miss the diagnosis of pulmonary hypertension, despite the fact that the symptoms are shortness of breath. So anybody with shortness of breath should be evaluated for their lung function, but also from the pulmonary vascular perspective. For the CTEPH part, the main initial test is a ventilation-perfusion scan. So you assess the perfusion of the lung, and you assess the ventilation of the lung, and if you see a mismatch of the perfusion, then you start the investigation for the potential diagnosis of CTEPH.
It's not something that physicians think of as a potential cause of shortness of breath. So one of the critical part is to increase awareness about the possibility of CTEPH as being a cause of dyspnea. The second step is to do the right test to rule in or rule out CTEPH, and the first step is to do a ventilation-perfusion scan, which is really the best test to have a screening tool to evaluate the possibility of CTEPH. So it's really to think about the diagnosis and then do the right test in order to make your diagnosis. If the ventilation-perfusion scan is abnormal that is enough to warrant a referral to a specialist center for treating patients with CTEPH.
The early diagnosis of CTEPH, or pulmonary hypertension is quite critical, in the sense that the evolution of the disease has an impact on the heart. Patients eventually develop heart failure as part of the natural progression of the disease. The early diagnosis of pulmonary hypertension allows the treatment to be started before the heart failure starts to become a problem, and the success of the treatment is much better. From a CTEPH perspective, this is even more critical in the sense that the CTEPH is treated with surgery, the pulmonary thromboendarterectomy, and development of the heart failure increases the risk of the surgery by up to 10 fold.
Early diagnosis of CTEPH can lead to much better results from a curative perspective, with the pulmonary endarterectomy. It also limits the risk of the surgery, so the surgery is much safer, and the success in the long term is much better from a curative perspective.
The diagnosis of CTEPH is potentially linked to pulmonary emboli. There's a lot of research to be done in order to follow some patients with pulmonary emboli, an acute event, in order to make sure that the resolution of the pulmonary emboli is complete. And if not, to be able to make an earlier diagnosis of CTEPH and potentially prevent the development of the pulmonary hypertension once you've had the blood clot.
CTEPH currently is treated permanently with the surgery, the pulmonary thromboendarterectomy. We, in the field of CTEPH, are developing new technique and technology in order to treat the disease without the surgery with minimally invasive approach. So we can go into the vessel of the lung, inflate a balloon in order to enlarge the vessel, and to potentially also cure patients with CTEPH with a minimally invasive approach. So this is a new field that is developing There is a lot of potential development in that direction in order to potentially cure the disease without the surgery, but with a minimally invasive treatment.
As the disease is diagnosed earlier, the success of these new technologies certainly is going to become much better as well in order to prevent the development of pulmonary hypertension. Potentially even, if the disease is caught at a stage where the pulmonary hypertension is not yet even present, but we can see the parameters that potentially will lead to pulmonary hypertension. So that's what the field is progressively evolving towards.
If you have somebody with shortness of breath, you should think of pulmonary vascular disease, and investigate it with either a CT pulmonary angiogram, or a V/Q scan as part of your evaluation on echocardiogram, as well as part of the evaluation for pulmonary hypertension. So anybody with shortness of breath, unless there’s a very clear cause for the shortness of breath, should have an echocardiogram on the evaluation of the pulmonary vascular disease, with some imaging.
I am Dr. Marc de Perrot, and I am aware that I am rare.
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