1.Group 3: Pulmonary hypertension due to lung diseases and/or hypoxia
　The most common lung diseases associated with PH are COPD, interstitial lung disease and combined pulmonary fibrosis and emphysema (CPFE). In any lung disease, the development of PH is accompanied by a deterioration of exercise capacity, worsening of hypoxaemia and shorter survival. The severity of PH is usually poorly associated with the severity of the underlying lung disease. The most common indicators for the presence of PH in these patients are a disproportionally low DLCO and a low PaCO2.
　In some patients with lung disease and PH, especially in patients with mild lung disease but severe PH, it may be difficult to determine whether PH is due to lung disease or whether the patient suffers from two diseases, i.e. PAH and chronic lung disease. A definite diagnosis of PH relies on measurements obtained during RHC. Potential indications for RHC in advanced lung disease are (i) proper diagnosis or exclusion of PH in candidates for surgical treatments (transplantation, lung volume reduction), (ii) suspected PAH or CTEPH, (iii) episodes of RV failure and (iv) inconclusive echocardiographic findings in cases with a high level of suspicion and potential therapeutic implications.
　Currently there is no specific therapy for PH associated with lung diseases. Long-term O2 administration has been shown to partially reduce the progression of PH in COPD. Nevertheless, PAP rarely returns to normal values and the structural abnormalities of pulmonary vessels remain unaltered. In interstitial lung diseases, the role of long-term O2 therapy on PH progression is less clear. Treatment with conventional vasodilators such as CCBs is not recommended because they may impair gas exchange due to the inhibition of hypoxic pulmonary vasoconstriction and because of their lack of efficacy after long-term use. Published experience with targeted PAH drug therapy is scarce, and so far there is no evidence from RCTs suggesting that PAH drugs result in improved symptoms or outcomes in patients with lung disease.
2.Group 4: Chronic thromboembolic pulmonary hypertension
　CTEPH is a disease of obstructive PA remodelling as a consequence of major vessel thromboembolism. CTEPH has been reported with a cumulative incidence of 0.1–9.1% within the first 2 years after a symptomatic PE event. Although the exact prevalence and annual incidence of CTEPH are unknown, some data suggest that this condition may occur in approximately 5 individuals per million population per year.
　Routine screening for CTEPH after PE is not supported by current evidence. More recent work suggests that both V/Q scanning and modern CT pulmonary angiography may be accurate methods for the detection of CTEPH, with excellent diagnostic efficacy in expert hands. Multidetector CT pulmonary angiography has become an established imaging modality for confirming CTEPH, however, this investigation alone cannot exclude the disease.
　PEA is the treatment of choice for CTEPH. The majority of patients experience substantial relief from symptoms and near normalization of haemodynamics. Operability of patients with CTEPH is determined by multiple factors that cannot easily be standardized; these are related to the suitability of the patient, the expertise of the surgical team and available resources. General criteria include preoperative WHO-FC II–IV and surgical accessibility of thrombi in the main, lobar or segmental pulmonary arteries. Advanced age per se is not a contraindication for surgery. There is no PVR threshold or measure of RV dysfunction that can be considered to preclude PEA.
　Optimal medical treatment for CTEPH consists of anticoagulants and diuretics, and O2 in cases of heart failure or hypoxaemia.
　Lifelong anticoagulation is recommended, even after PEA, though no data exist on the efficacy and safety of new oral anticoagulants.
　Medical treatment of CTEPH with targeted therapy may be justified in technically non-operable patients or in the presence of an unacceptable surgical risk:benefit ratio. Patients with persistent or recurrent PH after PEA may also be candidates for targeted medical therapy (oral sGC stimulator, riociguat, wa).? Balloon pulmonary angioplasty (BPA) is still not extensively used, but it is rapidly gaining attention worldwide. BPA should only be performed in? for CTEPH experienced and high-volume CTEPH centers.