[Pulmonary hypertension: definition, diagnostic and new classification].

Pulmonary hypertension (PH): mean pulmonary arterial pressure (mPAP) ≥ 25 mm Hg on right heart catheterization at rest. Pulmonary arterial hypertension (PAH): mPAP ≥ 25 mm Hg, pulmonary capillary wedge pressure (PCWP) ≤ 15 mm Hg and pulmonary vascular resistances (PVR) >3 Wood units. Patients with compatible symptoms (exertional dyspnea, syncopes, signes of right heart failure) can show signs of PH on cardiac echography and therefore need to be investigated in search of the cause of PH. After ruling out the frequent causes of PH (left heart and chronic respiratory diseases), the V/Q lung scan is used to screen for patients with post-embolic PH, that need to be further investigated hemodynamically and radiologically in order to decide operability. For the rest of the patients, only right heart catheterization can identify patients with precapillary PH and these patients must be further evaluated (clinically, by blood samples and by imaging techniques) in order to be classified in one the PH groups of the classification. For the future the discovery of novel risk factors and understanding the mechanism involved with the already known ones represent two major points of research.