By Shauna Mazenes
Patrick Himmelheber knew something was off when he struggled to catch his breath while playing hockey with friends.
As a healthy, 36-year-old man, he thought it was unusual. When changing his diet and exercise routine showed no improvements, he ended up quitting the team.
But it wasn't until six months later, when Patrick was gasping for air after simply walking or talking that he decided to see his doctor.
"I told him: everything is great — work is great, life is great," says Patrick. "But if I walk up a flight of stairs, I'm finished."
They learned Patrick had major clotting in the blood vessels in his lungs connecting to his heart, preventing him from breathing properly — a rare and fatal condition called chronic thromboembolic pulmonary hypertension (CTEPH).
He was referred to UHN’s thoracic surgery team, home of the largest CTEPH program in Canada, where he underwent a complex surgery to remove the blockages.
Today, Patrick has been cured of his condition.
"The surgery requires a lot of expertise from many areas," says Dr. Marc de Perrot, a thoracic surgeon and program director of UHN's Toronto CTEPH Program, who led Patrick's care.
"If it's not done properly, it carries a very high risk. But when done right, these patients are cured — pretty much forever."
CTEPH develops when blood clots in the lungs fail to dissolve properly, leaving behind scar tissue that narrows or blocks the pulmonary arteries. This scarring increases pressure in the lungs and places significant strain on the heart, often leading to heart failure if left untreated.
Patients also tend to experience uncomfortable symptoms in that time that impact their quality of life, such as shortness of breath and chest pain.
Patrick underwent a pulmonary thromboendarterectomy (PTE), a highly specialized procedure that removes persistent clots directly from pulmonary arteries. In the past, surgeons could only access and clear clotting from the main pulmonary arteries in the lungs, which can measure up to three centimetres wide.
Advances in imaging and surgical techniques now allow surgeons to remove clots from the much smaller and more delicate blood vessels deep within the lungs — some as narrow as one or two millimeters, where the clots often originate — making the procedure significantly more effective and potentially life saving.
UHN is one of the few centres in the world capable of doing this.
"Our surgical expertise has progressed over time and now we're doing the most complex cases — patients who were deemed not surgical elsewhere," says Dr. Laura Donahoe, a CTEPH surgeon and member of the CTEPH program since 2015.
The CTEPH program also brings together integrated transplant, cardiac, radiology, anesthesia, perfusion and ICU expertise, putting UHN at a unique advantage.
"There's really nobody else in the country who could have that degree of expertise across such a broad number of disciplines, all of which are essential to making this surgery safe and successful," says Dr. de Perrot.
CTEPH is often underdiagnosed as symptoms can be similar to other, more common conditions.
CT pulmonary angiograms and ventilation perfusion scans are the imaging tests used to diagnose CTEPH.
If clotting goes unaddressed for prolonged periods of time, it can cause the arteries to stiffen, leading to irreversible damage that surgery may not be able to fix.
Patrick arrived at UHN in time for the procedure to be effective.
Before his surgery, Patrick was prescribed heparin, a type of blood thinner injected twice a day, to keep his condition under control.
He was later admitted to the emergency room with a stabbing pain in his chest — a symptom of lung necrosis from the lack of oxygen reaching his lungs.
"A little piece of my lung actually died off, and it was scratching the nerves in my chest," says Patrick.
Patrick was referred to Dr. de Perrot and his team, who restored his blood flow and prevented future damage through the PTE procedure.
"We're trying to raise awareness so the diagnosis is made early, before any of that damage can happen," says Dr. de Perrot.
Today, Patrick is thriving. He recovered quickly and was discharged from the hospital seven days after his ten-hour surgery.
Dr. Donahoe says this is one of few surgeries where patients feel better almost immediately.
"These patients have been limited for so long," says Dr. Donahoe. "It really transforms them. They go back to work, go back to normal life. It's extremely gratifying."
While the risk factors for acute blood clots are well known, the reasons why some people go on to develop CTEPH remain unclear.
"We're trying to understand why some patients' blood clots don't resolve at the same level," says Dr. de Perrot. He compares it to how some people develop bad scarring after getting a cut, while others do not.
"It's the same process in the lungs. Why do patients heal with excellent scarring that is barely visible, versus patients who develop like a keloid or hypertrophic scar?"
So far, his research suggests that the healing process of blood clots in the lungs may produce a biomarker that ultimately leads to CTEPH.
UHN is also focused on training the next generation of surgeons.
Dr. de Perrot and his team have developed a
surgical simulator to help trainees build the dexterity and precision required to perform it safely.
"It's a very difficult procedure to teach and to learn," he explains. "The simulator helps us provide tools to train surgeons in how to work inside the artery — where the field of vision is extremely narrow and the margin for error is small."
