Right Pulmonary Artery

Overview

The right pulmonary artery is one of the two branches of the pulmonary trunk that transports deoxygenated blood from the right ventricle to the right lung. Despite being an artery, it carries oxygen-poor blood — a unique feature of pulmonary arteries compared to systemic arteries. The right pulmonary artery plays a central role in pulmonary circulation by delivering blood to the right lung for oxygenation.

Location

The right pulmonary artery arises from the pulmonary trunk at the level of the sternal angle (around T5–T6 vertebrae). It travels:

• Horizontally to the right, passing posterior to the ascending aorta and superior vena cava

• Anterior to the right main bronchus

• Enters the right lung at the hilum as part of the root of the lung

Once inside the lung, it divides into lobar and then segmental arteries to supply all regions of the right lung.

Structure

The right pulmonary artery is a thick-walled, elastic artery adapted for high-volume, low-pressure blood flow. It typically has:

• Origin: Pulmonary trunk

• Course: Longer and larger than the left pulmonary artery due to the heart's left-sided position

• Diameter: Approximately 1.5–2.5 cm in adults

• Wall composition: Tunica intima (endothelium), tunica media (elastic fibers and smooth muscle), and tunica adventitia

At the hilum, the right pulmonary artery typically lies anterior to the bronchus and superior to the pulmonary veins.

Function

The primary function of the right pulmonary artery is to:

• Transport deoxygenated blood from the right ventricle to the right lung

There, the blood flows through smaller arteries, arterioles, and capillaries surrounding the alveoli, allowing gas exchange to occur. The now oxygenated blood returns to the left atrium via the right pulmonary veins.

Physiological Role(s)

The right pulmonary artery contributes to several physiological processes:

• Gas exchange support: Delivers blood to alveolar capillaries for oxygen uptake and carbon dioxide release

• Low-pressure circulation: Operates under significantly lower pressure than systemic arteries to protect delicate pulmonary capillaries

• Dynamic flow adjustment: Can constrict or dilate in response to oxygen levels, optimizing ventilation-perfusion matching

• Right ventricular afterload regulation: Its resistance influences right ventricular workload and output

Clinical Significance

The right pulmonary artery is central to several cardiopulmonary conditions and clinical procedures:

• Pulmonary Hypertension: Increased pressure in the pulmonary arteries leads to right ventricular hypertrophy and failure. Often involves both left and right pulmonary arteries.

• Pulmonary Embolism (PE): A clot may lodge in the right pulmonary artery, reducing blood flow to the right lung and causing hypoxia, chest pain, or sudden death.

• Pulmonary Artery Stenosis: Narrowing of the right pulmonary artery (congenital or acquired) can cause reduced lung perfusion and right-sided pressure overload.

• Congenital Heart Disease: Abnormal development of the right pulmonary artery may be seen in conditions like Tetralogy of Fallot or truncus arteriosus. Surgical correction is often required.

• Right Heart Catheterization: The right pulmonary artery is a target site during catheter-based hemodynamic studies to measure pulmonary artery pressures and cardiac output.

• Imaging: CT pulmonary angiography and echocardiography are critical tools for assessing right pulmonary artery size, flow, and pathology.

Timely diagnosis and treatment of right pulmonary artery-related conditions are essential to prevent complications such as hypoxemia, pulmonary infarction, or right heart failure.