Basic concepts in pulmonary circulation

© 2017 Introduction: The normal adult pulmonary circulation is a low resistance and high capacitance system. Knowledge of its anatomy and physiology is important in order to understand the effects of pulmonary vascular disease on the functional status and prognosis in pulmonary hypertension. Objective: To analyse the anatomic-functional characteristics of pulmonary circulation and its changes with age and response to exercise, as well as to describe pulmonary artery stiffness and its relationship with afterload. Methodology: A narrative review is presented on the information available. Conclusions: The pulmonary arterial circulation is of dual origin: the extra-parenchymal “conduction” pulmonary arteries and the intrapulmonary “resistance” pulmonary arteries. The pulmonary arterial afterload can be estimated using the vascular resistance (stationery component) and the arterial compliance (pulsatile component) which has an inverse relationship, and its product represents the time constant. Pulmonary artery stiffness is a factor to regulate the dynamic afterload, and its increase is an early indication in the development of pulmonary hypertension. The response of the pulmonary circulation to exercise has an important role in the sub-clinical diagnosis of pulmonary hypertension.