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    From Cardiovascular System

    Left Coronary Artery
    Supplies blood to left side of heart.
    Heart
    Muscular organ responsible for pumping blood throughout the body.
    Posterior Tibial Arteries
    Supply posterior compartment of the leg.
    Fibrous Pericardium
    Outer layer of the pericardium made of dense connective tissue.
    Left Subclavian Artery
    Supplies the left upper limb.
    Popliteal Veins
    Drain blood from the knee region.
    Ulnar Arteries
    Supply the medial aspect of the forearm and hand.
    Common Iliac Arteries
    Branch from abdominal aorta to supply the lower limbs.
    Great Cardiac Vein
    Drains blood from the anterior surface of the heart.
    External Jugular Veins
    Drain blood from the face and scalp.
    Axillary Veins
    Drain the upper limbs and join with subclavian veins.
    Left Inferior Pulmonary Vein
    Returns oxygenated blood from left lung.
    External Iliac Arteries
    Continue into the legs as femoral arteries.
    Superior Vena Cava
    Returns deoxygenated blood from upper body.
    Femoral Veins
    Major deep veins of the thigh.
    Anterior Tibial Arteries
    Supply anterior compartment of the leg.
    Aortic Valve
    Valve between left ventricle and aorta.
    Left Pulmonary Artery
    Carries blood to left lung.
    Posterior Interventricular Branch
    Supplies posterior interventricular septum.
    Anterior Cardiac Veins
    Drain directly into the right atrium.
    Serous Pericardium
    Inner layer of the pericardium consisting of parietal and visceral layers.
    Right Ventricle
    Pumps blood to the lungs via pulmonary artery.
    Right Atrium
    Receives deoxygenated blood from the body.
    Trabeculae Carneae
    Irregular muscular columns on the walls of the ventricles.
    External Carotid Artery
    Supplies blood to the face and scalp.

    Pulmonary Valve

    Reviewed by our medical team

    Valve between right ventricle and pulmonary trunk.

    Overview

    The pulmonary valve is one of the four main valves of the heart, located at the junction between the right ventricle and the pulmonary trunk. It functions as a one-way valve that opens during ventricular systole to allow deoxygenated blood to flow into the pulmonary circulation and closes during diastole to prevent backflow into the right ventricle. Its structure and timing are essential for maintaining efficient pulmonary blood flow and overall cardiovascular stability.

    Location

    The pulmonary valve is situated at the outflow tract of the right ventricle, at the base of the pulmonary trunk. It is:

    • Anterior and leftward compared to the aortic valve

    • Just beneath the sternal end of the left third costal cartilage in surface anatomy

    • Posterior to the infundibulum (conus arteriosus) of the right ventricle

    It lies superior to the tricuspid valve and anterior to the aortic valve.

    Structure

    The pulmonary valve is a semilunar valve composed of three thin, crescent-shaped cusps:

    • Left semilunar cusp

    • Right semilunar cusp

    • Anterior semilunar cusp

    Each cusp is made of connective tissue and endothelium and contains:

    • A free edge that coapts with adjacent cusps during valve closure

    • A nodule at the center of the free edge to aid complete closure

    • Lunulae — thin margins extending from each nodule

    The valve is supported by the pulmonary annulus, a fibrous ring that anchors the cusps to the right ventricular outflow tract.

    Function

    The primary function of the pulmonary valve is to:

    • Allow unidirectional blood flow from the right ventricle to the pulmonary trunk during systole

    • Prevent regurgitation (backflow) of blood into the right ventricle during diastole

    It opens as the pressure in the right ventricle exceeds that in the pulmonary trunk and closes as the ventricular pressure drops below the pressure in the pulmonary arteries.

    Physiological Role(s)

    The pulmonary valve contributes to several key physiological functions:

    • Pressure regulation: Maintains low pulmonary artery pressure by preventing backflow, ensuring forward flow only during contraction

    • Efficiency of pulmonary circulation: Supports the rhythmic filling and emptying of the right heart and pulmonary arteries

    • Harmonization with cardiac cycle: Works in coordination with other heart valves to sustain effective cardiac output and pulmonary perfusion

    Clinical Significance

    The pulmonary valve is involved in several congenital and acquired heart conditions:

    • Pulmonary Valve Stenosis: A congenital narrowing of the valve opening that restricts blood flow from the right ventricle. It causes right ventricular hypertrophy and increased workload.

    • Pulmonary Valve Regurgitation: Incompetent valve closure allows blood to flow back into the right ventricle, potentially leading to right-sided volume overload and heart failure. It may result from pulmonary hypertension, valve repair, or endocarditis.

    • Tetralogy of Fallot: A congenital heart defect often associated with pulmonary stenosis. Surgical correction typically includes pulmonary valvotomy or valve replacement.

    • Endocarditis: Although rare, the pulmonary valve can be affected by infective endocarditis, especially in intravenous drug users or in patients with congenital defects.

    • Pulmonary Valve Replacement: Performed surgically or via transcatheter approaches (e.g., Melody valve) in patients with severe dysfunction, particularly post-congenital heart disease repair.

    • Auscultation: The pulmonary valve sound is best heard in the left second intercostal space near the sternal border — the pulmonary area of auscultation.

    Evaluation of the pulmonary valve is commonly done using transthoracic or transesophageal echocardiography, cardiac MRI, and CT. Prompt recognition and treatment of pulmonary valve diseases can significantly improve outcomes and prevent progression to right heart failure.

    Did you know? There are 4 types of blood — A, B, AB, and O — each with its own characteristics.