<unk>  is a pathophysiologic condition with many possible causes. Indeed, this condition frequently accompanies severe heart or lung conditions. A 1973 World Health Organization meeting was the first attempt to classify<unk>  by its cause, and a distinction was made between primary<unk>  (resulting from a disease of the pulmonary arteries) and secondary<unk>  (resulting secondary to other, non-vascular causes). Further, primary<unk>  was divided into the "arterial plexiform", "veno-occlusive" and "thromboembolic" forms. In 1998, a second conference at Évian-les-Bains addressed the causes of secondary<unk> . Subsequent third, fourth, and fifth (2013) World Symposia on PAH have further defined the classification of<unk> . The classification continues to evolve based on improved understanding of the disease mechanisms. Most recently in 2015, the WHO guidelines were updated by the European Society of Cardiology (ESC) and European Respiratory Society (ERS). These guidelines are endorsed by the International Society for Heart and Lung Transplantation, and provide the current framework for understanding and treatment of<unk> . Genetics Mutations in several genes have been associated with this condition these include bone morphogenetic protein receptor type 2 (BMPR2) and eukaryotic translation initiation factor 2 alpha kinase 4 gene (EIF2AK4).
Pulmonary hypertension
Portopulmonary hypertension
Chronic thromboembolic pulmonary hypertension
Asthma
Chronic obstructive pulmonary disease
Emphysema
Hypertensive heart disease
Reactive airway disease