Chronic thromboembolic pulmonary hypertension (CTEPH) is a potentially deadly and underdiagnosed condition that develops from unresorbed pulmonary emboli. A multidisciplinary team at Cleveland Clinic is one of just a handful across the U.S. that treats CTEPH, using the complex surgical procedure known as pulmonary thromboendarterectomy (PTE).
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“We want to spread the word, because CTEPH is vastly underrecognized,” says Gustavo Heresi-Davila, MD, Medical Director of the Pulmonary Thromboendarterectomy Program in Cleveland Clinic’s Department of Pulmonary and Critical Care Medicine. “There are many people affected by CTEPH who are not being diagnosed, yet there’s a highly effective surgical procedure that can cure most of them.”
PTE: Grace under pressure is a must
Performing a PTE requires a dedicated team, a highly skilled surgeon and extreme efficiency under pressure. It involves quick yet painstaking removal of thin scarred clot tissue lining the pulmonary arteries (Figure), with the patient rendered hypothermic to allow for periods of circulatory arrest on a heart-lung machine to enable a bloodless field.
Ideally, the procedure in each lung should be completed within 20 minutes, as that’s the longest a patient can remain in circulatory arrest before reperfusion is necessary. “There’s no tolerance for error,” says Nicholas Smedira, MD, the cardiothoracic surgeon who first performed PTE at Cleveland Clinic, starting in the mid-1990s. “You have to do it fast. It’s really, really hard surgery.”
Figure. Pulmonary thromboendarterectomy for CTEPH involves quick but painstaking removal of thin scarred clot tissue lining the pulmonary arteries. The residual scar is grasped and dissected from the lobar and segmental branches, as shown in the middle inset. The bottom inset shows an operative specimen. The procedure in each lung is ideally completed within 20 minutes to avoid the need for reperfusion.
In 2010, Dr. Heresi-Davila established a team at Cleveland Clinic to standardize protocols for PTE patient selection, preoperative evaluation, medical optimization and postoperative follow-up. The team includes members from pulmonary medicine, cardiothoracic surgery, nuclear medicine, radiology, cardiology, anesthesiology and critical care medicine.
Cure rates above 90 percent
Over the past 20 years, Dr. Smedira and the team have performed more than 160 PTE procedures, with current CTEPH cure rates of 90 to 95 percent. Since 2010, operative mortality has dropped from around 12 percent to less than 4 percent. And rates of significant complications — such as confusion and disorientation from neurologic injury, or respiratory dysfunction due to lung injury — are now below 10 percent.
The improvement over time, say both Drs. Heresi-Davila and Smedira, is due mainly to the protocol and the team.
“Major changes have taken place in the management of patients on the heart-lung machine [perfusion therapy], anesthesiology and postoperative critical care management,” notes Dr. Smedira. “Those have made a huge difference. But the way I do the operation today isn’t much different from 20 years ago.”
“It’s what happens before and after the operation that we have improved,” Dr. Heresi-Davila adds. “It’s a whole package of medical optimization that improves outcomes.”
As one of the most experienced centers for PTE in the nation, Cleveland Clinic has achieved PTE outcomes comparable to those of the University of California, San Diego, which pioneered PTE for CTEPH in the U.S. in the 1980s.
CTEPH: What referring clinicians need to know
For referring clinicians, the first step is recognizing CTEPH by considering it in the differential diagnosis of patients with pulmonary hypertension of unclear etiology, and even in those who merely have unexplained shortness of breath or exercise limitation.
“So much of treating CTEPH is recognizing its presence,” Dr. Smedira says. He notes that some patients don’t exhibit pulmonary hypertension at rest but have symptoms during exercise, as on a stress echocardiogram. For those in whom CTEPH is suspected, a lung ventilation/perfusion scan is the gold-standard screening tool.
The estimated incidence of CTEPH within two years of initial pulmonary embolism is about 4 percent, but that doesn’t account for the fact that many pulmonary emboli go unrecognized. In fact, some 30 percent of patients diagnosed with CTEPH have no history of pulmonary emboli even though all are likely to have experienced one.
Of the half million U.S. cases of pulmonary emboli per year, conservative estimates place the number of CTEPH cases at about 2,400 to 5,000 annually. With only roughly 500 PTE operations performed annually in the U.S., thousands of patients who might benefit from the procedure aren’t receiving it, Dr. Heresi-Davila notes.
Debunking misconceptions around PTE for CTEPH
Part of the reason, he continues, is that even when CTEPH is diagnosed, misconceptions prevent physicians from referring patients for PTE.
Although about one-third of patients will have contraindications to surgery — most notably very distal and surgically inaccessible clots or significant comorbidities — many other factors are not contraindications, such as older age or obesity. In fact, Dr. Smedira has performed successful PTEs in patients in their 70s and 80s and even in morbidly obese patients.
While severe pulmonary hypertension had been a deal-breaker in the past, it no longer is. “There’s no degree of pulmonary hypertension above which surgery isn’t feasible,” Dr. Heresi-Davila explains.
Another misconception is that CTEPH can be managed medically. Although anticoagulants are indicated to prevent further embolic events, they don’t improve established CTEPH or pulmonary hypertension. Although one medication, riociguat (Adempas®), was recently approved by the FDA to treat CTEPH, it is indicated only for patients who are not surgical candidates or who have residual or recurrent pulmonary hypertension after surgery.
In fact, Dr. Heresi-Davila notes, there are no hard end points that clearly identify nonoperable patients: “The decision about operability is complex, largely subjective and shaped by the team’s experience and expertise, which is why it needs to be made at an expert center. The stakes are high. If the surgery is a possibility, it offers the best outcome for patients.”