Exertional dyspnoea is a leading symptom in patients with pulmonary arterial hypertension (PAH). Patients suffering from PAH report poor quality of life, have skeletal muscle dysfunction and in the absence of advanced medical therapy deteriorate progressively due to right heart failure which can lead to death. For decades, patients with PAH were advised to avoid exercise in fear of exacerbated right heart failure. Recently, it has been shown that a highly supervised rehabilitation programme in expert centres leads to significant improvements in symptoms, quality of life, exercise capacity and may even enhance haemodynamics in selected stable patients treated with advanced regimens of PAH-targeted drugs. As a consequence of these promising results, pulmonary rehabilitation performed in an expert centre has been included in recent guidelines. The underlying mechanisms are not completely understood, but positive effects can be measured in different organ systems such as skeletal muscles, the cardiopulmonary system and immune system (inflammation), and also on the psychological level. Thus, improvements in 6-minute walking distance (6MWD), peak oxygen uptake (VO2 peak), muscle strength and muscle endurance, as well as physical and mental quality of life scores (SF-36 questionnaire) have been shown. Different training protocols have been used. Essential are qualified patient selection in expert centres, a low workload endurance and dumbbell (weight lifting) training avoiding strenuous exercise and exhaustion, thorough patient education and close supervision by experts especially during the first weeks. Adverse events may occur (e.g., pre-/syncope, arrhythmia, respiratory infections). PAH patients tend to overestimate their physical capacity, not perceiving their own limits properly, which makes education and expert advice even more important as exercise training can also worsen the right heart failure. Therefore, a core issue of the multidisciplinary rehabilitation is the close cooperation between the experienced rehabilitation clinic offering a specialised programme for PAH patients and the PAH expert centre, which takes care of the patient and is thoroughly involved in the training programme. Further multicentre international randomised trials are needed to evaluate whether this specialised programme is feasible within different healthcare systems and to assess long term effects and survival.

The term pulmonary hypertension refers to a serious condition characterised by high pulmonary vascular pressure, mainly as a consequence of various cardiac and respiratory diseases. Current clinical classification of pulmonary hypertension considers five distinct groups. Transthoracic echocardiography represents the first and most important noninvasive screening tool for estimating the probability of pulmonary hypertension. The diagnostic approach to pulmonary hypertension is supported by a proposed algorithm, which identifies the underlying cause. The definitive diagnosis and classification of pulmonary hypertension requires invasive confirmation of an elevated pulmonary artery mean pressure during a right heart catheterisation at rest. Pulmonary artery wedge pressure assessment has a pivotal role in differentiating precapillary from postcapillary pulmonary hypertension. The correct acquisition and interpretation of invasive pulmonary haemodynamic variables play a central role, not only in confirming the diagnosis but also in prognostication and treatment decision-making. During right heart catheterisation correct zero levelling of the external pressure transducer and pressure tracing readings at end-expiration should be assured. Obese patients and patients with obstructive lung diseases require special attention, given that spontaneous positive end-expiratory intrathoracic pressures are frequently observed. Because pressure and flow determinations with a fluid-filled flow-directed thermodilution catheter are potentially insufficiently precise, it is recommended to average at least three measurements. Acute vasoreactivity testing is indicated only in selected patients. Recent data suggest that invasive pulmonary haemodynamic measurement during exercise may be more sensitive than resting haemodynamics for early diagnosis, for treatment response assessment and for prognostic purposes.

Pulmonary hypertension associated with left-sided heart disease (PH-LHD) is the most common type of pulmonary hypertension. In patients with left-sided heart disease, the presence of pulmonary hypertension is typically a marker of more advanced disease, more severe symptoms, and worse prognosis. In contrast to pulmonary arterial hypertension, PH-LHD is characterised by an elevated pulmonary artery wedge pressure (postcapillary pulmonary hypertension) without or with an additional precapillary component (isolated postcapillary versus combined postcapillary and precapillary pulmonary hypertension). Transthoracic echocardiography is the primary nonin-vasive imaging tool to estimate the probability of pulmonary hypertension and to establish a working diagnosis on the mechanism of pulmonary hyperten-sion. However, right heart catheterisation is always required if significant pulmonary hypertension is sus-pected and exact knowledge of the haemodynamic constellation is necessary. The haemodynamic con-stellation (mean pulmonary artery pressure, mean pulmonary artery wedge pressure, left ventricular end-diastolic pressure) in combination with clinical infor-mation and imaging findings (mainly echocardiog-raphy, coronary angiography and cardiac magnetic resonance imaging) will usually allow the exact mech-anism underlying PH-LHD to be defined, which is a prerequisite for appropriate treatment. The general principle for the management of PH-LHD is to treat the underlying left-sided heart disease in an optimal man-ner using drugs and/or interventional or surgical ther-apy. There is currently no established indication for pulmonary arterial hypertension-specific therapies in PH-LHD, and specific therapies may even cause harm in patients with PH-LHD.