Present status of primary pulmonary hypertension

More than a century has passed since the first description of pulmonary arteriosclerosis of unknown origin. The development of our understanding of primary pulmonary hypertension (PPH) can be divided into four periods. The first period, which extended from the introduction of the concept until about 1930, may be described as the dawn of this disease. In the second period (1930-1950) the morphological aspects of the disease were recognized and studied. In the third period (1950-1960), the advent of right heart catheterization made it possible to link pathological physiology with morphology and the disease entity as primary pulmonary hypertension was firmly established. Since 1960 (the fourth period) the etiology and therapy of this disease have been studied. This paper will review chronologically the history of PPH since the 19th century and then will discuss the etiologies, pathology, and clinical manifestation including symptoms and signs, laboratory findings, therapy, and prognosis based on the nationwide survey in Japan as well as the author's own experience.