This article will describe the unique behavior of the pulmonary circulation under conditions of acute and chronic stress. The four points to be described are as follows: (1) the unique nature and function of the pulmonary vascular bed; (2) the pulmonary vascular response to pulmonary venous hypertension, specifically mitral stenosis; (3) how the pulmonary vessels maintain their basic function, despite a sudden reduction of vascular volume by one half, and while having to contend with high flow, high pressure, or high pulmonary vascular resistance; and (4) the response of the pulmonary vasculature to closure of defects in congenital heart disease.
Much of this information has been discussed elsewhere, with extensive bibliographic documentation.1
Bronchial arteries nourish the lung and mediastinal structures. The pulmonary arterial system has no metabolic function. Its main purpose is the transport of gases from the body to the pulmonary capillaries (carbon dioxide) and away