Definition of PH

Pulmonary hypertension (PH) is pathophysiologic consequence of vasculopathic changes in the pulmonary vessels that may occur as a result of predisposing factors. Pulmonary arterial hypertension (PAH) is characterized by the presence of precapillary PH in absence of other causes of precapillary PH and of postcapillary (=venous) PH.

PAH is defined by specific hemodynamic criteria obtained via right heart catheterization (RHC), including a mean pulmonary arterial pressure (mPAP) >20 mm Hg, pulmonary artery wedge pressure  (PAWP) ≤15mmHg and a PVR > 2WU. (see table).

Humbert M.,  European Heart Journal (2022) 00,1–114

Important definitions

PH is a haemodynamic and pathophysiological condition defined as an increase in Ppa ≥20 mmHg at rest as assessed by right heart catheterisation. PH can be found in multiple clinical conditions.

The definition of PH on exercise as Ppa >30 mmHg as assessed by right heart catheterisation is not supported by published data.

PAH (group 1) is a clinical condition charecterised by the presence of pre-capillary PH in the absence of other causes of pre-capillary PH such as PH due to lung dieseases, chronic thromboembolic PH, or other rare diseases. PAH includes different forms that share a similar clinical picture and virtually identical pathological changes of the lung microcirculation.

PH: pulmonary hypertension; Ppa: mean pulmonary arterial pressure; PAH: pulmonary arterial hypertension.

Haemodynamic definitions of pulmonary hypertension

mPAP: mean pulmonary arterial pressure; PAWP: pulmonary arterial wedge pressure; PVR: pulmonary vascular resistance; WU: Wood Units. #: group 1: PAH; group 2: PH due to left heart disease; group 3: PH due to lung diseases and/or hypoxia; group 4: PH due to pulmonary artery obstructions; group 5: PH with unclear and/or multifactorial mechanisms.