[Definition and Classification of Pulmonary Hypertension]

Pulmonary Hypertension (PH) is characterized as a hemodynamic disorder defined by a mean pulmonary arterial pressure (mPAP) exceeding 20 mmHg at rest. Classification into distinct subtypes is guided by measurements of pulmonary arterial wedge pressure (PAWP) and pulmonary vascular resistance (PVR): Precapillary PH: PAWP ≤ 15 mmHg accompanied by PVR > 2 Wood Units (WU), isolated Postcapillary PH: PAWP > 15 mmHg with PVR ≤ 2 WU and combined Pre- and Postcapillary PH: PAWP > 15 mmHg with PVR > 2 WU.Exercise-Induced PH refers to a pathophysiological condition in which resting mPAP is within normal limits but exhibits an exaggerated rise during physical exertion. This is quantified by a slope of mPAP relative to cardiac output exceeding 3 mmHg per liter per minute between rest and activity.The foundational framework for the clinical classification of PH, comprising five principal groups, remains unchanged. Nevertheless, several updates have been introduced: Reintegration of long-term responders to calcium channel blockers as a distinct subset within idiopathic pulmonary arterial hypertension (IPAH), Inclusion of new subcategories under Group 2 PH, which encompasses PH associated with left heart disease and Revision of Group 3 PH to categorize patients based on underlying pulmonary pathology rather than solely functional impairment.Additionally, Mitomycin-C and Carfilzomib have been recognized as pharmacologic agents with a confirmed causal relationship to the development of pulmonary arterial hypertension (PAH) and have thus been added to the list of definitively associated drugs.