The European Respiratory Review is structured around a “theme of the month”. I am delighted to introduce pulmonary hypertension (PH) as the first theme of the new Review.
PH describes a group of devastating diseases, comprising idiopathic and associated/secondary forms, which cause breathlessness, loss of exercise capacity and death due to elevated pulmonary artery pressure and subsequent right heart failure [1]. Pulmonary arterial hypertension (PAH) is defined by an elevation of the mean pulmonary artery pressure above 25 mmHg at rest and/or 30 mmHg during exercise without elevation of the pulmonary capillary wedge pressure (≤15 mmHg) [1]. The underlying pathophysiological mechanism is extensive pulmonary artery remodelling [2]. PH was previously classified into two categories, namely primary or secondary PH, depending on the absence or presence of identifiable causes or risk factors [1]. In the second (1998), third (2003), and fourth (2008) World Symposium on PH, a detailed clinical classification of the disease was agreed upon. The 2003 version is shown in table 1 [1]. The main subcategories share similarities in pathogenetic mechanisms, clinical presentation and therapeutic options, allowing clinicians to conduct trials using homogeneous groups of patients. Similarly, basic science specialists have attempted to describe pathophysiological mechanisms in the same homogeneous groups of patients with PH.
PAH
This includes cases without identifiable cause or risk factors, so-called idiopathic PAH (sporadic appearance) and familial PAH [1]. For these subgroups, mutations in the bone morphogenetic protein (BMP)/transforming growth factor-β superfamily (BMPR2, activin receptor-like kinase-1 and endoglin) are now known to play …