In chronic thromboembolic pulmonary hypertension (CTEPH), persistent thrombi are formed as organized tissue, which obliterates the pulmonary arteries. This results in increased pulmonary vascular resistance, which in turn results in an increase in mean pulmonary arterial pressure (≥25 mmHg at rest) with progressive right heart failure. Most of the patients are diagnosed as a result progressive exercise dyspnoea.
Signs of right heart failure may be associated with fatigue, rapid vulnerability, syncope or demise. Often there is an interval of a few months to several years between the initial event of acute embolism and the onset of clinical symptoms.
The cause of CTEPH is unknown. In up to 60% of patients, there is no evidence of an acute pulmonary embolism in the patient's own history. Also, the prevalence is not clearly determinable, since it is assumed that the disease is often not even diagnosed. On average, two years elapse between the onset of first symptoms and the time of diagnosis. With regard to the pathophysiological mechanism of CTEPH, an association with the decreased blood flow through the pulmonary arteries is suspected.
After initial obliteration by unresolved thrombi, there is an increase in vascular remodeling in unclosed vasculature. Perfusion scintigraphy is the gold standard to exclude a CTEPH. Right ventricular catheters and pulmonary angiography are required to ensure diagnosis and treatment planning. Operative pulmonary endarterectomy (PEA) is the only potentially curative therapy for CTEPH. Left untreated, the prognosis of the is poor.