Anatomy/Ultrasonography of the Heart

The heart is surrounded by the aerated lungs and bony thoracic cage, all of which create a challenging environment for the acquisition of ultrasound images. There are important differences in the orientation of the ultrasound probe used for transthoracic echocardiography and traditional ultrasonography. There are three primary windows used to interrogate the heart: parasternal, apical and subxiphoid. Often, the planes in each window are named according to the primary axes/planes of the heart, which are: the long axis; the short axis; and the four-chamber plane. The parasternal long-axis (PLAX) shows the following structures in a single plane: left atrium (LA), mitral valve, left ventricle (LV), left ventricular outflow tract, aortic valve and aortic root. Subxiphoid/Subcostal (SC) window is most commonly used to obtain images in the four-chamber plane, but also provides excellent short axis views, especially in patients with hyperinflated lungs or enlarge livers.