Thoracic surgery
Thoracic surgeon Dr. Marc De Perrot, (R), has developed the world's first pulmonary endarterectomy simulator in an effort to decrease the length of time it takes new surgeons to learn the technique, thereby broadening the pool of specialists who can offer the procedure. (Photo: UHN)​

It resembles something out of a Tim Burton film: raw, red tree-like monsters with what look like angry, twisted branches.  But rather than being the stuff of movie nightmares, it's in fact scar tissue that has been carefully removed from inside the arteries of a patient's lungs.

The scarring is the result of chronic thromboembolic pulmonary hypertension (CTEPH) when a mass caused by blood clots gets caught in the lungs' blood vessels and blocks blood flow. The blood clots are caused by an acute pulmonary embolism (PE) – when a blood clot travels from one part of the body into the lungs and gets stuck.

Though a PE can be resolved with blood thinners, CTEPH can develop anywhere from a few months to decades after it occurs. While rare, CTEPH is also under-recognized since its symptoms – shortness of breath, dizziness, fatigue – are similar to other lung diseases and ailments.

Left untreated, individuals with CTEPH can die within three to five years. But a new world-first simulator, developed by Toronto Western Hospital thoracic surgeon Marc De Perrot in partnership with the National Research Council (NRC) and support from a Bayer HYPE innovation grant, is designed to teach a key treatment option for those with CTEPH to more surgeons.

More surgeons will be able to learn the procedure

The simulator will help teach pulmonary endarterectomy (PEA) surgery, which removes scar tissue from the pulmonary arteries in the lungs, to more surgeons, offering the potential of a huge improvement in the quality of life for patients such as Patrick Himmelheber, 37.

When Patrick couldn't catch his breath during his first recreational hockey game of the season in the fall of 2015, he just thought he had let himself get out of shape over the summer.

"It was the beginning of the season and I got winded as soon as I got on the ice," recalls Patrick. "I figured I really needed to work on my cardio, but it got to the point that I couldn't play without getting short of breath and I quit the team.

"It was very weird to be so short of breath because I'm a pretty fit person and exercised regularly," he continues. "But every time I exerted myself, even to go up the stairs, I couldn't breathe."

Blood clots
Scar tissue removed from Patrick Himmelheber's lungs. The scarring is the result of chronic thromboembolic pulmonary hypertension (CTEPH) when a mass caused by blood clots gets caught in the lungs’ blood vessels and blocks blood flow. (Photo: Courtesy Patrick Himmelheber)

Patrick struggled with his condition for eight months and finally decided to broach the issue with his doctor at Toronto Western Hospital's Family Health Team. Since he otherwise felt fine and really wanted to underscore the degree to which he was short of breath, he asked Dr. Taylor Ferrier if he could demonstrate by walking up a set of stairs together. 

As they walked up the stairs, Patrick's breathing immediately became laboured, he couldn't talk and had to stop to catch his breath.

Dr. Ferrier suspected PE and first ordered blood work but it came back showing nothing out of the ordinary. He spoke to his peers and the consensus was to do a CT scan to be safe. The scan revealed that Patrick had blood clots in both of his lungs. He was immediately sent to the Emergency Department, put on blood thinners and admitted overnight for observation.

"Later on, my family doctor would tell me that I was lucky to be alive," says Patrick. "The amount of clotting they found in my lungs would have been detrimental to anyone who hadn't been as physically active as I was."

Patrick would need PEA surgery

Once stabilized, patients who experience PE are referred to Toronto General Hospital's (TGH) CTEPH Clinic for follow-up. Patrick went for his appointment a few days later where he was prescribed a twice daily injected blood thinner for a month and scheduled for further follow-up in the fall.

Patrick went on with his life; travelling, enjoying the summer and spending time with his wife. As his follow-up appointment day approached, he figured it would be a routine formality. But the day before, Patrick's morning routine was interrupted by sharp pain in his chest.

His wife rushed him to TWH Emergency where he was relieved to hear that he didn't have any new clots. However, the diagnosis was very concerning: as a result of his earlier PE, necrosis – a side effect of CTEPH – was taking hold of his right lung and a very small part of his lung had died from the lack of blood flow in its arteries.

The chest pain was a result of the scar tissue from the necrosis pushing on his chest, and he would need surgery to remove it. Individuals with CTEPH that is left untreated can die within three to five years.

After a summer of feeling relatively secure about his diagnosis and treatment, Patrick now found himself seated across from a thoracic surgeon with an uncertain future ahead.

Fortunately, the thoracic surgeon in question was Dr. De Perrot, whose surgical expertise focuses on procedures for end-stage lung diseases including CTEPH which is treated via PEA.

Guy using simulator
A year in development, the visual simulator, pictured here, aims to reduce by six months the training time to learn the PEA procedure. (Photo: Courtesy Bayer)

Less than a month after his consultation with Dr. De Perrot, Patrick underwent asurgery of about eight hours to separate and remove the scar tissue from his lungs' arteries.

For Patrick, it was happenstance that connected him with Dr. De Perrot – as an existing patient at UHN, he was referred to the appropriate physician who had the specialized expertise and skill to diagnose and treat his condition.

But there is a steep learning curve for thoracic surgeons to learn the PEA procedure that can result in high risk of mortality. Currently, PEA is only offered at a few specialized centres in the world.

"Thoracic surgeons learn PEA by assisting during the procedure," explains Dr. De Perrot. "Working in a lung's artery with magnifying glasses is delicate work making the technique difficult to teach – only one surgeon at a time can look through the artery during the procedure to see all the intricate detail."

As such, learning the procedure can take about two years, making it difficult to more quickly enlarge the pool of surgeons who can offer PEA.

But Dr. De Perrot hopes to change all that. He spent a year developing the visual simulator, which aims to reduce training time for the procedure by six months.

Improved quality of life

The simulator, installed this month in the Temerty-Chang International Centre for Telesimulation and Innovation in Medical Education, will give trainees the opportunity to practice the delicate and complex procedure using a virtual platform in 3-D. It also allows experienced surgeons to train others remotely. The goal is to gather ongoing feedback from trainees to further refine the simulator.

"CTEPH is expected to increase in prevalence over the next 10 years," says Dr. De Perrot. "With surgery, the five-year survival rate increases to 89 per cent and patients return to full function within a few months, so it is imperative to get more thoracic surgeons trained in this skill set and I'm pleased to be a part of the solution."

One patient can certainly attest what access to this procedure has done for his quality of life.

Following his surgery, Patrick spent a week in the hospital and was then discharged. He felt an immediate difference as a result of the surgery and is slowly returning to normal life, going back to work on the two-month anniversary of the procedure.

He now also volunteers for the Thoracic Surgery Clinic acting as a point person for patients about to undergo PEA with whom he shares his experience to provide comfort and reassurance so they have an idea of what to expect and can see what recovery looks like.

"I'm still on blood thinners and maybe I will be forever," he says. "But I am light years away from what I was feeling back in 2015."​

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