The lungs are supplied by two separate vascular systems, consisting of the pulmonary and bronchial arteries. The pulmonary arteries carry deoxygenated blood at low pressure. The connection between the pulmonary and bronchial arteries also lies in the fact that they, bypassing the capillaries, form vascular anastomoses. They supply 99% of the blood flow to the lungs and are involved in gas exchange at the alveolar capillary membrane.
Functions of bronchial arteries
These arteries supply the supporting structures of the lungs, including the pulmonary arteries, but are not normally involved in gas exchange. Branches of the bronchial artery carry oxygenated blood to the lungs at a pressure six times the pressure in the pulmonary arteries. They are connected to the lungs by several microvascular anastomoses at the level of the alveoli and respiratory bronchioles.
In various cases that are associated with pulmonary artery compromise (eg, vasculitis and chronic pulmonary thromboembolic disease), the arteries and their anastomoticconnections can expand, allowing a greater percentage of cardiac output to flow through the bronchial artery system.
Location
The bronchial arteries usually originate from the proximal descending thoracic aorta. They are called orthotopic when they are between the upper end plate of the T5 vertebral body and the lower end plate of the T6 vertebral body. Angiography milestone for orthotopic arteries 1 cm above or below the level of the left main bronchus when transecting the descending thoracic aorta.
Bronchial arteries that are located elsewhere in the aorta or originate from other vessels are called ectopic.
On a CT angiography examining hemoptysis, 64% of patients had orthotopic arteries and the remaining 36% had at least one ectopic artery, most commonly arising from the inferior surface of the aortic arch.
Other reports after bronchial ultrasound indicate the presence of ectopic arteries in 8.3-56% of all patients, depending on the method of examination (i.e., autopsy or angiography).
Potential ectopic origins include:
- inferior aortic arch;
- distal descending thoracic aorta;
- subclavian artery;
- thyroid cell;
- internal mammary artery;
- coronary artery.
The bronchial arteries, which originate from the coronary artery, can cause myocardial infarction orangina due to coronary theft.
Clinical relevance
Bronchial arteries can be changed in various pathologies. For example, they expand and become tortuous in the case of hypertension in pulmonary thromboembolism. For some diseases (bronchiectasis, cancer, tuberculosis, etc.) that cause hemoptysis, arterial embolization can be used to stop the bleeding.
Resistance of bronchial arteries to atherosclerosis
It is still unknown if arteriosclerotic disease affects these arteries.
But US scientists conducted a pilot study to estimate the prevalence of arteriosclerosis, correlate it with certain clinical and laboratory parameters of arteriosclerotic disease or any coexisting coronary artery disease, and confirm the clinical significance.
Arteries 10-15 mm long were taken from 40 patients with a mean age of 62-63 years. Their medical history and detailed clinical and laboratory risk factors for arteriosclerosis were recorded.
After USGD of bronchial arteries, their average diameter was 0.97 mm. Histology revealed medial calcific sclerosis in only 1 patient (2.5%) without concurrent established atherosclerotic lesions or luminal narrowing. In addition, vessel diameter was significantly correlated not only with the highest stage of the disease (p=0.031), but also with proximal bronchial branch occlusion (p=0.042). The researchers noted a slight correlation betweenatherosclerosis and metabolic syndrome (p=0.075).
Definition of the pulmonary artery and its function
The pulmonary artery begins at the level of the right ventricle of the heart and then splits in two to reach each lung, where it divides into many branches. The role of the pulmonary artery is to transport blood, depleting its oxygen, from the heart to the lungs. Pulmonary embolism can occur in the pulmonary artery when it is obstructed by a clot that cuts off circulation. Divers sometimes become victims of pulmonary embolism after the formation of a gas bubble in the pulmonary artery.
Arrangement of branches
The branch of the pulmonary artery has a length that ranges from 4.5 cm to 5 cm. Its diameter is 3.5 cm and its thickness is about 1 mm.
The horizontal part of the chest touches the pulmonary branch along its entire length.
The pulmonary artery is surrounded by a serosa that is characteristic of the aorta.
Pulmonary artery disease
A pulmonary embolism is a blockage of an artery by a clot or gas bubble that does not dissolve in the blood. Arteries usually suffer from the consequences of thromboembolic disease. Methods for diagnosing pulmonary embolism:
- perfusion scintigraphy to see the difference between normal lung ventilation and clot-impaired vascularity. This examination is able to detect the difference between ventilation and perfusion, so that an accurate diagnosis of the patient can be made;
- angioscope(arteriography/CT) is used to diagnose an already diseased lung.
Some congenital heart defects can adversely affect these arteries:
- absence or atresia of the pulmonary artery;
- narrowing or stenosis of the pulmonary artery;
- wrong location.
If the pulmonary artery pressure is too high, then pulmonary arterial hypertension or PAH is diagnosed, which is a disease completely different from general arterial hypertension. It can be either primitive (that is, without a cause) or secondary.
Superior and inferior vena cava
The human body has two types of vena cava: superior vena cava and inferior vena cava. Both serve to carry blood from the organs to the heart. Thus, the inferior vena cava receives blood from various organs located in the abdominal cavity, digestive tract and lower extremities through the portal vein.
The superior vena cava collects blood from the head, neck, chest, and upper extremities through the azygos vein. These veins have a common point in the right atrium of the heart.
Conclusion
The bronchial arteries should not be confused with the pulmonary arteries. They are part of the pulmonary circulation and provide functional lung vascularization by bringing oxygenated white blood from the right ventricle to be oxygenated. On the other hand, bronchial arteries play an important role: they bring to the lungsoxygenated and nutrient-rich blood.
