In bronchiectasis, areas of the bronchial walls are destroyed and chronically inflamed, the ciliated cells are damaged or destroyed, and mucus production increases. The increased mucus promotes the growth of bacteria, often obstructs the bronchus, and leads to pooling of infected secretions and further damage to the bronchial wall. In severe cases, scarring and a loss of blood vessels in the lung ultimately can strain the heart. Also, inflammation and an increase in blood vessels in the bronchial wall can cause a person to cough up blood. Blockage of the damaged airways can lead to abnormally low levels of oxygen in the blood.
Many conditions can cause bronchiectasis.
Abnormal immune responses, birth abnormalities affecting the structure of the airways or the ability of cilia to clear mucus, and mechanical factors such as bronchial obstruction may predispose a person to infections that lead to bronchiectasis. A small number of cases probably result from inhaling toxic substances that injure the bronchi. Although bronchiectasis can develop at any age, most often the process begins in early childhood. However, symptoms may not appear until much later, or they may never appear. Symptoms begin gradually, usually after a respiratory tract infection, and tend to worsen over the years.