Chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is an underdiagnosed form of pulmonary hypertension (PH). Its pathogenesis is poorly understood but probably arises as a result of a failure to resolve an acute pulmonary embolism (PE). Overtime, the acute fibrinous clot is organised into fibrous tissue occluding the pulmonary arteries. In addition, there is a distal vasculopathy, similar to that seen in pulmonary arterial hypertension. Both these processes increase right ventricular afterload, which in turn leads to right ventricular failure.

 

CTEPH should be suspected in post PE patients with persistent breathlessness after 3 months of appropriate anticoagulation. Echocardiography is a useful screening test in these patients. However, right heart catheterisation is required to confirm the presence of pre-capillary PH. CT pulmonary angiography can identify the burden and distribution of chronic thromboembolic material. 

 

Pulmonary endarterectomy (PEA) surgery may provide a cure for the disease in patients with a significant burden of proximal chronic thromboembolic material. Even in experienced centres the mortality of PEA surgery is estimated between 1-5%. Therefore, careful patient assessment is required to determine suitability for PEA surgery.

 

Balloon pulmonary angioplasty (BPA) is suitable for patients with a more distal distribution of chronic thromboembolic material as a first line intervention or in patients with residual PH post PEA.

 

Pulmonary artery vasodilator therapies are also used in patients with inoperable CTEPH or residual PH post PEA. Although, riociguat is the only drug proven to be efficacious in randomised clinical trials.