A pulmonary arterial hypertension 1). organic changes of pulmonary vessels a thickening of the vessels b deterioration of emphysema c. Decreased capillary bed: >70% 2). functional changes of pulmonary vessels factors of body fluid, tissue and nerveA. pulmonary arterial hypertension 1). organic changes of pulmonary vessels a. thickening of the vessels b. deterioration of emphysema c. Decreased capillary bed:>70% 2). functional changes of pulmonary vessels factors of body fluid, tissue and nerve