Chronic thromboembolic pulmonary hypertension; how does it develop and how can it be recognised?

Abstract

Chronic thromboembolic pulmonary hypertension (CTEPH), which has been recognised in the past in no more than 0.1% patients who had undergone acute pulmonary embolism (APE), is currently being found in as many as 3–8% of these patients. The pathophysiology of CTEPH is not fully understood, although the relationship with venous thromboembolism has a firm basis. The potential causes of the disease include symptomatic but unrecognised episodes of APE, repetitive episodes of silent pulmonary microemboli and recurrence of symptomatic APE in the course of initial treatment during and after the cessation of secondary antithrombotic prophylaxis. The pathomechanisms postulated are failure to lyse the initial emboli, coagulopathy, thrombosis in situ and peripheral propagation of the residual emboli. The role of arteriopathy in the initial stage of CTEPH is controversial.
CTEPH should be expected in all patients with chronic exertional dyspnoea and exercise intolerance in whom other causes can be excluded. The role of medical history, physical examination, electrocardiography and echocardiography in recognition is under discussion. Early diagnosis, before the development of pulmonary hypertension, is likely to ensure a good prognosis in continuously anticoagulated patients. Most patients, however, are diagnosed late and pulmonary hypertension is already marked. At this stage of CTEPH pulmonary endarterectomy is the treatment of choice for suitable patients with proximal emboli. Diagnosis of CTEPH at the stage of decompensated cor pulmonale considerably worsens the prognosis in solely anticoagulated patients and decreases the benefits of pulmonary endarterectomy.