The Pathophysiology of Scleroderma Involving the Heart and Respiratory System

Abstract

Tests of pulmonary function were carried out in 38 patients with scleroderma and in 18 of them cardiac catheterizations were also done. The pulmonary vascular resistance was increased in all the hemodynamic studies. About half of these cases had slight elevations of pulmonary vascular resistance unaccompanied by clinical signs of right ventricular hypertrophy. The remainder showed moderate to marked elevations of pulmonary vascular resistance and clinical signs of right ventricular insufficiency. The pulmonary hypertension in scleroderma occurs independently of the alterations in pulmonary function. It is suggested that "scleroderma heart disease" as a distinct entity is not usually of major physiologic importance but that the heart is mainly affected secondarily by pulmonary or systemic hypertension. Only about 5% of our cases with scleroderma had completely normal lung volumes and mechanics of breathing. Most of the remainder showed restrictive lung disease manifested by reduced vital capacity, normal functional residual and total lung capacities, low lung compliance, low airway resistance and normal pulmonary resistance. Gaseous diffusion was impaired regardless of the degree of disturbances in other pulmonary function tests. Tightness of the skin over the chest wall did not affect respiratory function as evidenced by normal thoracic compliance and maximum pressures developed by the chest bellows.