ABSTRACT
There are many potential causes of PAH and it therefore represents a heterogeneous clinical phenomenon that requires further elucidation to ensure appropriate screening, diagnosis, and management (Figure 2.1).16-18
Diagnostic classification In order to facilitate the detection, diagnosis, and treatment of the many forms of pulmonary hypertension, including PAH, the WHO sponsored an expert consensus conference in Evian, in 1998 where a formal classification system was formulated. This system was recently updated and published following an expert meeting in Venice, in 2003.1
Table 2.1 shows the current classification system used to categorize the various forms of PH and the specific subcategory of PAH. It is important to note that modifications in the nomenclature relating to PAH involved the replacement of the term primary pulmonary hypertension (PPH) in favour of idiopathic PAH, and the recognition of familial PAH as a separate category. In addition, PAH is recognized as being ‘related to’ rather than ‘secondary to’ coexisting diseases such as connective tissue disease, HIV infection, and portal hypertension. Changes to other categories of pulmonary hypertension clarify terminology rather than rearrange the whole classification system devised by the WHO working group in 1998.
