Pulmonary Arterial Hypertension (part one)

Pulmonary hypertension is usually classified as primary (idiopathic) or secondary.1 It is now clear, however, that there are conditions within the category of secondary pulmonary hypertension that resemble primary pulmonary hypertension in their histopathological features and their response to treatment. For this reason, the World Health Organization (WHO) classified pulmonary hypertension into five groups on the basis of mechanisms, rather than associated conditions. In 2003, the World Health Organization revised the classification of PAH into 5 categories based in part on etiology: pulmonaryarterial hypertension, pulmonary venous hypertension, pulmonary hypertension associated with hypoxemia, pulmonary hypertension resulting from chronic thrombotic or embolic disease, and miscellaneous. 2 Group I of the WHO classification, designated pulmonary arterial hypertension, is the principal focus of this review. Pulmonary arterial hypertension is defined as a sustained elevation of pulmonary arterial pressure to more than 25 mm Hg at rest or to more than 30 mm Hg with exercise, with a mean pulmonary-capillary wedge pressure and left ventricular end-diastolic pressure of less than 15 mm Hg.3Diagnosis of PPH one must excludes all secondary cause of PHT and demonstrate normal pulmonary wedge pressure. 2,3