Why does the pulmonary artery carry venous blood?
Aug 21, 2025
Source: Cainiu Health
Dr. Liu Feng
Introduction
Under normal circumstances, the main reasons for venous blood flowing into the pulmonary artery include the physiological structure of the pulmonary circulation, the functional demands of gas exchange, atrial septal defect, ventricular septal defect, pulmonary artery stenosis, and similar conditions. If discomfort symptoms occur, it is recommended to seek timely medical consultation and treatment at a正规 hospital. In daily life, one should maintain a regular作息 schedule and avoid excessive fatigue; engage in appropriate physical exercise to enhance cardiopulmonary function.
Generally, the main reasons why venous blood flows through the pulmonary artery include the physiological structure of the pulmonary circulation, the functional demands of gas exchange, atrial septal defect, ventricular septal defect, and pulmonary artery stenosis. If discomfort symptoms occur, it is recommended to seek timely medical treatment at a qualified hospital. The specific analysis is as follows:
1. Physiological Structure of the Pulmonary Circulation
The human circulatory system is divided into systemic circulation and pulmonary circulation. The pulmonary artery is the starting vessel of the pulmonary circulation, connecting to the right ventricle, which receives venous blood returning from the entire body. This innate physiological structure determines that the blood flowing through the pulmonary artery is venous blood. This is a normal physiological phenomenon and does not require special intervention.
2. Functional Demands of Gas Exchange
Venous blood has low oxygen content and high carbon dioxide content. The pulmonary artery transports venous blood to the lungs, where gas exchange occurs in the alveoli, expelling carbon dioxide and taking in oxygen, thus converting venous blood into arterial blood. This is a necessary process for achieving gas exchange. Maintaining lung health and avoiding behaviors that impair lung function, such as smoking, are sufficient.
3. Atrial Septal Defect
An atrial septal defect causes arterial blood from the left atrium to flow into the right atrium, mixing with venous blood before entering the right ventricle and pulmonary artery, resulting in an abnormal proportion of venous blood within the pulmonary artery. Symptoms can be relieved under a doctor's guidance with medications such as digoxin tablets, furosemide tablets, and spironolactone tablets. Severe cases may require surgical treatment.
4. Ventricular Septal Defect
A ventricular septal defect allows arterial blood from the left ventricle to flow into the right ventricle, mixing with venous blood, thereby increasing the proportion of venous blood flowing through the pulmonary artery. Medications such as captopril tablets, enalapril tablets, and benazepril tablets may be used as directed by a physician, and surgical repair may be necessary when needed.
5. Pulmonary Artery Stenosis
Pulmonary artery stenosis hinders blood flow, leading to increased pressure in the right ventricle and impairing the normal entry of venous blood into the lungs, causing venous blood to accumulate in the pulmonary artery. Mild stenosis can be monitored regularly, while severe cases may require medications such as warfarin sodium tablets, aspirin enteric-coated tablets, and clopidogrel bisulfate tablets under a doctor's guidance, or surgical expansion of the narrowed area.
In daily life, it is important to maintain a regular routine and avoid excessive fatigue; engage in appropriate physical exercise to enhance cardiopulmonary function; and undergo regular medical check-ups to detect and address heart-related diseases promptly.
