We really appreciate the letter written by Rossi UG1 referring to our paper entitled “Bronchial artery pseudoaneurysm and mediastinal hematoma after EBUS-TBNA”, published in Archivos de Bronconeumología.2 We take the chance to briefly review the vascular anatomy of the airway and the bronchial abnormalities that can be encountered during bronchoscopy.
Knowledge of the vascular anatomy of the airways is imperative to recognize the vascular abnormalities involving the bronchial arteries during bronchoscopy. These abnormalities can result from primary airways disorders or from other diseases which lead to the involvement of the airway vasculature. As hemoptysis is the main clinical manifestation, its recognition is essential for the appropriate management in life-threatening situations.
The lung is supplied by two vascular systems, the pulmonary and systemic (bronchial) arteries, which are connected through microvascular anastomoses at the level of the respiratory bronchioles and alveoli. The bronchial arteries usually originate from the proximal descending thoracic aorta, between the superior endplate of the T5 vertebral body and the inferior endplate of the T6 vertebral body. These are called orthotopic bronchial arteries. The term ectopic is employed when these arteries originate elsewhere in the aorta or from other vessels (i.e., intercostal or internal mammary arteries). Bronchial arteries supply oxygenated blood to the tracheobronchial tree up to the terminal bronchioles, to the visceral pleura and irrigates some mediastinal structures including hiliar lymph nodes or esophagus.
Bronchial artery malformations can present as aneurysms or pseudoaneurysms, which are difficult to distinguish clinically and bronchoscopically. Although most patients are asymptomatic, the condition may result in massive hemoptysis.
Dilated bronchial arteries have >2mm in diameter and a frequent tortuous mediastinal course. Pulmonary artery obstruction or parenchymal lung diseases cause chronic pulmonary ischemia leading to hypertrophy or enlargement of bronchial circulation in an effort to maintain blood flow to the affected lung and gas exchange through systemic-pulmonary arterial anastomoses. Among the conditions associated with bronchial enlargement we find congenital disorders (Tetralogy of Fallot or ALCAPA syndrome) or acquired diseases, including infections, chronic thromboembolic disease, Takayasu arteritis, fibrosing mediastinitis, trauma, lung cancer or bronchiectasis.
Congenital anomalies in the pulmonary venous system and cardiac malformations with prolonged pulmonary venous hypertension lead to bronchial vessel dilatation and variceal formation. These conditions present in childhood with recurrent pneumonia and hemoptysis. Mucosal hyperemia, tortuous airway vasculature and varices are typical findings in the bronchoscopy.3
Chronic airways diseases such as bronchiectasis, asthma, chronic obstructive pulmonary disease or sarcoidosis produce changes in the pulmonary vasculature. Bronchiectasis is the most common cause of hemoptysis since bronchial artery enlarge, with even aneurysm or pseudoaneurysm formation.4 CT detection of these vascular lesions is important to avoid procedures in the affected areas during bronchoscopy. Vascular changes in asthma have been described in the bronchial microcirculation and include angiogenesis, dilation and hyperpermeability.5 Collagen vascular disorders like Marfan syndrome or Bechet's disease can also produce bronchial aneurysms.
Although vascular patterns observed during bronchoscopy in the different mentioned disorders may not be specific, its recognition help to determine the underlying pathophysiology and to choose the appropriate management.
