Pulmonary hypertension in the interstitial lung diseases.

T he interstitial lung diseases, like many chronic lung diseases, may lead to the development of pulmonary hypertension and cor pulmonale. The prevalence of pulmonary hypertension in these diseases is unknown, however. Current data suggest that prevalence varies with the type ofinterstitial disease.'3 In a group of patients with either idiopathic pulmonary fibrosis or interstitial lung disease associated with a collagen vascular disorder, 70 percent had ausculatory findings consistent with pulmonary hypertension.2 These data are in agreement with those of Stack et al,4 who found that 68 percent of patients with terminal fibrosing alveolitis died with advanced fibrotic lung disease and cor pulmonale. Although considerable data are available on the pathogenesis of pulmonary hypertension in the interstitial lung diseases, the exact pathogenetic mechanism remains unknown. Current data suggest that the etiology of pulmonary hyperten-sion in the interstitial diseases is multifactorial and involves the following: 1) primary lesions of the pulmonary vessels (eg, vasculitis in sarcoidosis),1'5 2) compression anchor destruction of pulmonary vessels by the interstitial process,5'6 and 3) vasoconstriction of vessels mediated by hypoxia, acidosis, or autacoids.5'7'8 Additional factors that may modulate pulmonary artery pressure include pulmonary blood volume, pulmonary artery compliance, lung water,, temperature, and left ventricular function.5'9 " 2 The contribution of each of these factors to the genesis of pulmonary hy-pertension in patients with interstitial lung disease is speculative, but quite likely varies with the type of in-terstitial disease, course of the disease, and individual susceptibility. Treatment of pulmonary hypertension secondary to chronic pulmonary disease poses a difficult problem for the clinician. Clearly, the major therapeutic emphasis should be directed toward the underlying lung disease. For example, in patients with chronic obstructive lung disease, treatment with bronchodilators and antimicrobials may result in lowering pulmonary artery pressure.5 In patients with alveolar hypoxia, supplemental 02 has also been shown to improve pulmonary hemodynamics. Despite optimal treatment of the underlying chronic pulmonary disease, however, symptomatic pulmonary hypertension with cor pulmonale often persists. Widespread use of vasodilating agents in systemic hypertension and in the management of left ventricu-lar failure has encouraged a similar approach in patients with pulmonary hypertension. Both primary pulmonary hypertension and pulmonary hypertension secondary to chronic lung disease have been studied. Several potent vasodilator agents including hy