CHAPTER SUMMARY AND CENTRAL ILLUSTRATION
This chapter summarizes the diagnosis, pathophysiology, and treatment of various forms of pulmonary hypertension. Pulmonary hypertension is defined by a mean pulmonary artery pressure >20 mm Hg, and it can arise from primary pulmonary vascular pathology (WHO group 1), left heart disease (WHO group 2), lung disease (WHO group 3), or chronic thromboembolic disease (WHO group 4) (see Fuster and Hurst’s Central Illustration). The diagnosis of pulmonary hypertension can be suspected from noninvasive testing, but it requires confirmation with invasive right heart catheterization. Group 1 pulmonary hypertension is frequently idiopathic and associated with poor outcomes, but multiple pharmacological treatment options are now available to improve symptoms and prognosis. Group 4 pulmonary hypertension requires treatment directed toward mechanical relief of thromboembolic obstruction with pharmacological therapy reserved for inoperable or residual disease. Pulmonary hypertension for groups 2 and 3 primarily involves treatment directed toward the underlying pathology. Regardless of etiology, worsening pulmonary hypertension and associated right heart dysfunction are associated with poor outcomes. The diagnostic and therapeutic approach to pulmonary hypertension requires careful clinical phenotyping and thoughtful consideration of the multiple treatment options available.
eFig 57-01 Chapter 57: Pulmonary Hypertension
DEFINITION OF PULMONARY HYPERTENSION
Pulmonary hypertension (PH) refers to a pathologic elevation of pressure in the pulmonary artery (PA). In contrast to systemic hypertension where etiologic evaluation is rarely undertaken, it is important to determine the underlying cause of PH because there are specific treatments directed for some of the specific etiologies. The presence of PH was traditionally defined by a mean PA pressure ≥25 mm Hg, but this has recently been revised to include patients with a mean PA pressure >20 mm Hg.1 The term pulmonary arterial hypertension (PAH) is typically used to connote patients with PH that is caused by an elevation in the pulmonary vascular resistance (PVR) that is not secondary to other disorders such as heart disease or hypoxemic lung disease. There is a paucity of evidence to guide treatment decisions in patients with a mean PA pressure between 21 and 25 mm Hg, and most of the literature to date has primarily evaluated patients with a mean PA pressure ≥25 mm Hg.
EPIDEMIOLOGY AND CLASSIFICATION OF PULMONARY HYPERTENSION
Regardless of etiology, the presence of an elevated PA pressure is consistently associated with poor prognosis.2,3,4 PH affects approximately 1% of the world’s population, and increases with aging.5 PH is categorized as being “postcapillary” when the cause is distal to the alveolar-pulmonary capillary interface (predominantly in the left heart), or “precapillary” when the pathologic process affecting the pulmonary arterial vessels. The prevalence of PH is higher in developing countries where previously important causes of PH such as rheumatic heart disease, unrepaired congenital heart disease, schistosomiasis, and human immunodeficiency ...