Pulmonary hypertension is a fatal lung and heart disease. It is characterized by shortness of breath, fatigue and fainting. It is exacerbated by an increase of the pressure in the lung vasculature through exercise, leading to progressive worsening of hemodynamics, right ventricular hypertrophy, right heart insufficiency and finally right heart failure. This book focuses on pulmonary arterial hypertension, a rare and progressive subgroup of pulmonary hypertension, which is today incurable and terminally faal. Classification of pulmonary arterial hypertension, its pathology, and strategies for future therapy will be of interest both to those suffering from the disease and those who take care of patients. This volume will also engage physicians and other scientists contributing to an understanding of the pathophysiology of pulmonary arterial hypertension and attempting to extend life of humans with pulmonary arterial hypertension by developing causal and curative therapies.