Even with the limited access to the heart afforded by the left
parasternal, apical, and subcostal transducer positions, it is possible
to direct an ultrasound beam at most cardiac structures. For M-mode,
it is relatively simple to describe the beam orientation in terms
of the structures encountered, but for two-dimensional recordings
it is possible to obtain an almost infinite variety of cross-sectional
images of the heart. It is therefore desirable to standardize on
a limited number of views that cover the majority of applications,
and that can be described readily in terms of transducer orientation
and anatomical features.
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| Fig. 13 |
To this end, it has been agreed that two-dimensional echocardiographic
images should be based on three orthogonal planes, as shown in Fig.
13. The long-axis plane transects the heart from the aortic
root to the left ventricular apex and includes the aortic and mitral
valves. On the surface of the body, it is almost perpendicular to
the plane of the sternum and runs approximately from the subject's
right shoulder to the left kidney. The short axis approximates to
the plane of the atrioventricular junction. On the surface of the
body, it is at right angles to the plane of the sternum and runs
from the left midclavicle to the right hip. The four-chamber plane
is at right angles to both the long and short axes. It runs from
the apex to the base of the heart and is approximately perpendicular
to both the posterior interventricular septum and the interatrial
septum. As its name implies, it includes parts of each of the four
cardiac chambers. On the surface, it is parallel to the plane of
the sternum, and includes both the apex and the right shoulder.
As can be appreciated from Fig.
13, the three best echocardiographic approaches to the heart
correspond approximately to the points at which the three standard
planes intersect. Thus, from the left parasternal transducer position,
it is possible to examine the long-axis and short-axis planes. From
the apical position, the long-axis and four-chamber planes can be
visualized, and from the subcostal position, the four-chamber and
short-axis planes.
2004