Pulmonary arterial hypertension: pathophysiology and anesthetic approach.

IN 1998, the World Health Organization sponsored a symposium on pulmonary hypertension at which a new, more clinically useful classification system was adopted.§ Traditionally, pulmonary hypertension had been classified as being primary or secondary. The classification proposed at the World Health Organization symposium divides pulmonary hypertension into five distinct categories (table 1): (1) pulmonary arterial hypertension (PAH) associated primary pulmonary hypertension (PPH) (familial and sporadic) and PAH related to collagen vascular disease, congenital systemic to pulmonary shunts, HIV infection, portopulmonary hypertension, drugs such as anorexigens, and toxins; (2) PAH linked with disorders of the respiratory system and/or hypoxemia; (3) pulmonary venous hypertension, including mitral valve disease, chronic left ventricular dysfunction, and pulmonary venoocclusive disease; (4) PAH due to chronic thrombotic and/or embolic disease; and (5) PAH attributed to disorders directly affecting the pulmonary vasculature (inflammatory pulmonary capillary hemangiomatosis).