CTEPH — Surgical therapy and new FDA-approved medical treatment
Chronic thromboembolic pulmonary hypertension (CTEPH), an underappreciated cause of severe pulmonary arterial hypertension (PAH), usually presents with progressive exertional dyspnea. Approximately 75 percent of patients with CTEPH have a documented history of acute pulmonary embolism; 50 percent have had a previous deep venous thrombosis.
CTEPH is characterized by:
- Increased pulmonary vascular pressures determined by right heart catheterization (mean pulmonary artery pressure greater than 25 mm Hg and pulmonary vascular resistance, or PVR, greater than 240 dynes/s/cm-5)
- Imaging evidence of obstruction within the pulmonary arterial bed by vascular webs, intimal irregularities and luminal narrowing, all arising as the thrombus gradually incorporates into the pulmonary endothelium
These abnormalities may be detected using various imaging modalities, including nuclear ventilation-perfusion scanning, pulmonary angiography or CT angiography. Patients with CTEPH and these abnormalities are uniquely identified as Group 4 in the Dana Point classification of pulmonary hypertension.
Integrated approach to management
Mayo Clinic provides an integrated approach to the management of patients with pulmonary hypertension. The Pulmonary Hypertension Clinic at Mayo Clinic in Rochester, Minnesota, is staffed by cardiologists, pulmonologists, interventional radiologists and cardiothoracic surgeons with expertise in the diagnosis and treatment of CTEPH.
Conventional pulmonary angiography best discerns whether the obstruction is proximal enough for pulmonary thromboendarterectomy (PTE), a potentially curative procedure. Surgical selection depends on:
- Severity of pulmonary hemodynamic abnormality (usually PVR between 600 and 1,200 dynes/s/cm-5)
- Degree of symptoms
- Lesion location
The procedure is conducted via median sternotomy and cardiopulmonary bypass hypothermic circulatory arrest and is a true endarterectomy (as opposed to an embolectomy).
Although approximately 40 percent of patients with CTEPH will not be operable, in those who undergo PTE, recent series have reported normalization of pulmonary hemodynamics in 25 to 35 percent. Lifelong anticoagulation is advised.
The Food and Drug Administration recently approved riociguat (Adempas), a pulmonary vasodilator that acts through the endogenous nitric-oxide cyclic GMP pathway, as the first medical alternative for CTEPH patients who are not operative candidates or who have persistent PAH following pulmonary endarterectomy. Recent trials of riociguat have shown improvements in exercise capacity and PVR, though improvements in RV function with this treatment haven't yet been demonstrated.