Primary Pulmonary Hypertension

PRIMARY pulmonary hypertension (PPH) is a term currently used to define the presence of pulmonary hypertension of unexplained etiology. Although the disease entity was recognized in the early 1900s, it was not until 1951 that Dresdale coined the termprimary pulmonary hypertension, which is used today. The purpose of this update is to review the salient features of PPH and highlight some future directions. DIAGNOSIS To make the diagnosis of PPH, certain positive and negative clinical criteria must be met. It cannot be overemphasized that PPH is a diagnosis of exclusion and is only as reliable as the extent to which secondary causes of pulmonary hypertension have been ruled out. The most common secondary causes of pulmonary hypertension and the methods by which they can be diagnosed or excluded are listed in Table 1. The emphasis on making an accurate diagnosis is underscored because therapies for secondary forms of pulmonary