Pulmonary Valve/Artery Anatomy & Function

Objectives
 
At the completion of this chapter the student will be able to:
 
  • Discuss the Anatomy and Function of the Pulmonary Valve and Pulmonary Artery
  • Recognize and Use the Standard and Non Standard Views of the Pulmonary Valve and Pulmonary Artery
  • Discuss the Echocardiographic Evaluation of the Pulmonary Valve and Pulmonary Artery
  • Discuss the Echocardiographic Evaluation of Pulmonary Regurgitation
  • Discuss the Echocardiographic Evaluation of Pulmonary Stenosis
  • Discuss Other Diseases of the Pulmonary Valve and Pulmonary Artery
  • Recognize Important Echocardiographic Factors for the Pulmonary Valve For a Ross Procedure
Introduction

 
Anatomy & Function
 

The pulmonary valve (PV) is structurally similar to the  aortic valve (AV) and shares close embryologic evolution.  The PV is located between the right ventricular outflow tract and the pulmonary artery.  The PV, like the AV, is a semilunar, trileaflet valve which has 3 leaflets or cusps, a sinotubular junction and sinus of Valsalva for each cusp.

This structural similarity is due to the similar embryologic origins. Both semilunar valves develop from ridges of the aorta and pulmonary trunks after partitioning of the bulbus cordis and the truncus arteriosus has occurred. The three cusps are named by their orientation: right, left, and anterior.  (An alternate naming scheme is anterior, right posterior, and left posterior.)  The right and left cusps lie anterior to the AV right and left coronary cusps.    The PV cusps are thinner than the AV cusps, and are sometimes difficult to visualize in the far field in echocardiographic scans.

The PV has small nodes along the free margin called the nodulus Arantii (or the Nodes of Arantii) similar to the AV nodes.  A small half-moon shaped area along the free edge that can contain perforations called the lunula is also present, although not clinically significant . 

 
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Pulmonary Valve Anatomy Image
RVOTd = Right Ventricular Diameter Diastole
PVAn = Pulmonary Valve Annular Diameter
MPAd = Main Pulmonary Artery Diameter
 

The PV annulus is less defined and more distensible than the AV because it is attached to right ventricular muscle instead of a fibrous ring. The PV area is similar to the AV area (2 cm2/m2).  Both valves have a sinotubular junction diameter that is about 10-15% smaller than their respective annular diameters.

The function of the PV is to prevent the retrograde flow of blood from the pulmonary artery into the right ventricle. The PV is analogous to the AV in anatomy and also in function except that the right side of the heart is a low pressure system. The opening and closing of the pulmonary valve correlates with that of the AV. 

Pulmonary Valve
 
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Nodes of Arantii Pulmonary Valve
The right ventricular outflow tract (RVOT) is defined as that part of the right ventricle from the crista terminalis to the pulmonary valve annulus. It is a relatively trabeculated portion of the right ventricle. Because the RVOT is a muscular portion of the right ventricle, diseases which increase right ventricular pressure, such as pulmonary hypertension or pulmonary valvular stenosis, may result in right ventricular hypertrophy of the RVOT. Hypertrophy of the RVOT can cause dynamic outflow obstruction. The RVOT is the most anterior portion of the heart and lies under the sternum making it easily visualized by transthoracic echocardiography but is a relatively deep structure for TEEPage 360.
 
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RVOT Image RVH Video or Image (Modified RVIO View)
The main pulmonary artery is defined as the structure between the PV annulus and the division of the right and left pulmonary arteries.  The right pulmonary artery travels posterior to the ascending aorta.  The left pulmonary artery travels anterior to the left bronchus.  Because the left pulmonary artery travels anterior to the left bronchus, imaging of the left pulmonary artery may be difficult from the esophageal acoustic windows.