Chronic bronchitis affects about 3 percent of the American population, most commonly men over age 40. Having an identical twin with chronic bronchitis. Chronic bronchitis may be divided into four subtypes. Chronic bronchitis with obstruction involves significant airway obstruction in addition to a chronic cough. In this condition, the airways become narrowed, limiting the amount of oxygen that gets to the air sacs.
Blood vessels constrict in an attempt to divert the blood to better-oxygenated areas of the lung.
Vessel constriction leads to high pressures in the arteries that feed the lungs and puts a strain on the right side of the heart. Eventually, if blood pressure remains high enough in the lungs, the right side of the heart begins to fail and the blood backs up in the liver, intestines and legs. In this disorder, the tiny air sacs in the lungs, called alveoli, are destroyed. The lungs are unable to contract fully, and gradually lose elasticity. As a result, breathing may become labored and inefficient, resulting in a persistent feeling of breathlessness.