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| Figs. 32-35 |
If the transducer is tilted toward the apex, the ultrasound beam
scans a lower plane, as indicated in Figs.
32-35. At this level, the left ventricle is sectioned across
the middle of its two papillary muscle groups. These are normally
easy to visualize and they form a reliable means of identifying
ventricular morphology, since the right ventricle has only one prominent
papillary muscle. The right boundary of the left ventricle is formed
by the lateral free wall and the bottom of the section by the inferior
wall. To the left is the muscular interventricular septum. This
section cuts the right ventricle very close to its apex. The deep
trabeculation in this region may be apparent.
In addition to identification of ventricular situs, this view is
useful for segmental analysis of wall motion in patients with ventricular
disease. For this purpose, the ventricular wall is divided into
a number of segments, typically 10 to 15, and the motion and thickening
of each is assessed independently. For example, the short-axis views
at mitral valve and papillary muscle levels might be divided into
five segments each, with an additional four segments derived from
the apical long-axis and short-axis views. This provides a disciplined
approach to analysis of ischemic disease, but as with all echocardiographic
methods, it frequently fails due to technical difficulty in visualizing
all the segments adequately.
2004