LV Segmental Anatomy and Perfusion
An overview of the general segmental anatomy of the left ventricle and the associated coronary perfusion
Missing a wall motion abnormality in a patient with globally preserved LV systolic function could miss an important sign of ischemic disease. Some forms of non-ischemic cardiomyopathy can also have regional wall motion abnormalities but other aspects of LV function would not be normal in these patients.
The LV is roughly divided into longitudinal thirds; BASE (mitral annulus to the papillary muscles), MID VENTRICLE (papillaries to the distal third), and APEX (distal third). This image is from 123sonography.com.
There is then a circumferential division of the LV into six zones (only four out at the apex). These can be nicely labeled on the following PSAX view taken at the MV level.
Going around the circle starting with the upper right are the Anterior, Anterolateral, Inferolateral, Inferior, Inferoseptal, and Anteroseptal segments.
The two terminologies are combined to describe the location of a wall motion abnormality (e.g. basal inferolateral). This terminology is only learned through repetition. A learner must frequently and routinely get all the cardiac views and specifically note, and name, the major wall segments.
The routine PLAX view of the heart is a section through the anteroseptal and inferolateral segments, as shown on the following image. The apical3 view shows these same walls (with everything tipped up), but the apical region may be better seen.
A typical PLAX shows only 2 of the 6 segments of the LV and only the basal and mid-LV portions of these. A typical PSAX shows maybe 4 or 5 segments, because often the more lateral LV wall is difficult to see because of lung and the apex is often obscured. Thus, the apical views are usually required to have a better view of all the LV segments.
The standard apical4 view shows the inferoseptal and the anterolateral LV as shown on the following image. Thus, the PLAX and the apical4 usually show 4 of the 6 circumferential sections of the LV.
The more elusive 2 segments of the LV are the true inferior and anterior walls and these are seen with the apical 2 view as shown in the next clip. The inferior wall is to the left on the indicator side and the anterior wall is to the right of the image.
As noted in the previous chapter, a short axis view in the subcostal window may be able to create a view similar to a PSAX allowing a good assessment of radial function and of each LV segment.
Wall motion abnormalities vary from an area that thickens less with systole and doesn’t move quite as well (hypokinesia) to more obvious abnormalities of thinned myocardium that doesn’t move at all (akinesia) and myocardium that bulges the wrong way with systole (dyskinesia). This image is from 123sonography.
When abnormal wall segments are identified, the next image identifies the coronary perfusion of the different regions of the heart. This image was taken from the American and European echocardiography societies publication on cardiac chamber quantification in J Am Soc Echocardiogr 2015;24:1-39.
It takes much repetition to learn this organization. Notice particularly that over half the heart has two different ways that it can be perfused, so we don’t emphasize naming a culprit coronary artery.