The lungs are supplied with two separate vascular systems consisting of pulmonary and bronchial arteries. Pulmonary arteries carry deoxygenated blood at low pressure. The relationship of 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 on the alveolar capillary membrane.
The functions of the bronchial arteries
These arteries provide nutrition to the supporting structures of the lungs, including the pulmonary arteries, but usually do not participate in gas exchange. Branches of the bronchial artery transfer oxygen blood to the lungs at a pressure six times the pressure in the pulmonary arteries. They are associated with pulmonary by several microvascular anastomoses at the level of the alveoli and respiratory bronchioles.
In various cases that are associated with a compromised pulmonary artery (for example, vasculitis and chronic pulmonary thromboembolic disease), arteries and their anastomotic compounds can expand, allowing a greater percentage of cardiac output to flow through the bronchial artery system.
Location
The bronchial arteries, as a rule, originate from the proximal descending thoracic aorta. They are called orthotopic when they are located between the upper end plate of the T5 vertebral body and the lower end plate of the T6 vertebral body. Milestone for orthotopic arteries with angiography 1 cm above or below the level of the left main bronchus at the intersection of the descending thoracic aorta.
Bronchial arteries that are located elsewhere in the aorta or exit from other vessels are called ectopic.
In an angiographic CT scan that evaluated hemoptysis, orthotopic arteries were found in 64% of the patients, and the remaining 36% had at least one ectopic artery, most often arising from the lower surface of the aortic arch.
Other reports after ultrasound of the bronchial arteries indicate the presence of ectopic arteries in 8.3-56% of all patients, depending on the examination method (i.e. autopsy or angiography).
Potential ectopic foci of origin include:
- inferior aortic arch;
- distal descending thoracic aorta;
- subclavian artery ;
- thyroid cell;
- internal mammary artery;
- coronary artery.
Bronchial arteries that originate from the coronary artery can cause myocardial infarction or angina pectoris due to coronary theft.
Clinical relevance
Bronchial arteries can be changed with various pathologies. For example, they expand and become sinuous in case of pulmonary thromboembolism hypertension . For some diseases (bronchiectasis, cancer, tuberculosis, etc.) that lead to hemoptysis, arterial embolization can be used to stop bleeding.
Resistance of bronchial arteries to atherosclerosis
It is still unknown whether arteriosclerotic disease affects these arteries.
But American scientists conducted an experimental study to assess the prevalence of arteriosclerosis of the arteries, compare it with certain clinical and laboratory arteriosclerotic parameters or any coexisting coronary artery disease, and confirm the clinical significance.
Arteries 10-15 mm long were taken from 40 patients with an average age of 62-63 years. Their medical history and detailed clinical and laboratory risk factors for arteriosclerosis were recorded.
After ultrasound examination of the bronchial arteries, their average diameter was 0.97 mm. Histology revealed medial calcific sclerosis in only 1 patient (2.5%) without concurrent atherosclerotic lesions or narrowing of the lumen. In addition, the diameter of the vessel was significantly correlated not only with the highest stage of the disease (p = 0.031), but also with proximal occlusion of the bronchial branch (p = 0.042). Scientists noted a slight correlation between atherosclerosis 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 into two parts to reach each lung, where it is divided into many branches. The role of the pulmonary artery is to transport blood by depleting its oxygen, from the heart to the lungs. Pulmonary embolism can occur in the pulmonary artery when it is blocked by a clot that interrupts blood circulation. Divers sometimes become victims of pulmonary embolism after the formation of a gas bubble in the pulmonary artery.
Branch Location
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 serous membrane, which is characteristic of the aorta.
Pulmonary artery disease
Pulmonary embolism is a blockage of the arteries with a clot or gas bubble that does not dissolve in the blood. Arteries usually suffer from the effects of thromboembolic disease. Diagnostic methods for pulmonary embolism:
- perfusion scintigraphy, which allows you to see the difference between normal ventilation of the lungs and vascularization disturbed by a clot. This examination is able to detect the difference between ventilation and perfusion, so that you can establish an accurate diagnosis of the patient;
- An 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;
- incorrect 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, for no reason) 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 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 limbs through the azigin vein. These veins have a common point in the right atrium of the heart.
Conclusion
Bronchial arteries should not be confused with pulmonary arteries. They are part of the pulmonary circulation and provide functional vascularization of the lungs, bringing oxygen-white blood from the right ventricle to be saturated with oxygen. On the other hand, bronchial arteries play an important role: they bring oxygen-containing and nutrient-rich blood to the lungs.