The new definition of pulmonary hypertension

Despite the progress that has been made in the field of pulmonary hypertension (PH) 1–3, there is no unifying and globally accepted definition of the condition. The first official haemodynamic definition of PH was proposed at the First World Symposium on Pulmonary Hypertension which took place 1973 in Geneva, Switzerland as a World Health Organization (WHO)-sponsored meeting 4. This conference was triggered by the previous epidemic of PH associated with the appetite suppressant aminorex 5. As such, the focus of that meeting was primary pulmonary hypertension (PPH), as compared to the other forms of PH. After a long and sometimes heated debate the consensus was to define PPH by a mean pulmonary artery pressure (P̄_pa) >25 mmHg at rest or >30 mmHg during exercise in the presence of a pulmonary capillary wedge pressure (P_pcw) ≤15 mmHg.

This definition was later extended to other forms of pulmonary arterial hypertension (PAH) 6. It stood the test of time for >30 yrs, but was challenged during the Fourth World Symposium on Pulmonary Hypertension, which took place 2008 in Dana Point, CA, USA. There were several reasons for this: 1) the old definition did not take into account other forms of PH; 2) the threshold of P̄_{pa …}