hypertrophy is commonly associated with any form of right ventricular
or pulmonary hypertension, which may in turn
owe its origin to left-sided disease. The echocardiographic signs
are thickening of the anterior right ventricular wall and the septum
(Fig. 7). Cavity size is usually normal, or slightly enlarged. In
many cases there is associated volume overload present due to tricuspid
regurgitation, in the absence of this, septal motion is normal.
Unfortunately, M-mode echocardiography is insensitive for detecting
right ventricular hypertrophy due to the lack of spatial information.
Specificity is poor due to a number of factors, including variable
orientation of the right ventricular walls to the ultrasound beam
and the numerous other possible causes of septal thickening. Where
some right ventricular hypertrophy is present, the papillary muscles
attached to the right ventricular wall enlarge, and the path of
the ultrasound beam may include these in the apparent septal thickness.
Any condition affecting the right side of the heart tends to cause
some cardiac rotation. The path of the ultrasound beam crosses a
different region of the ventricle from normal, resulting in an apparent
change in dimensions. Finally, there is the difficulty of an adequate
`gold standard' against which to judge echocardiographic findings.
Two-dimensional echocardiography overcomes many of these problems.
(Fig. 8) shows a parasternal long axis in systole from a patient
with right ventricular hypertrophy.
The subcostal approach is a
superior view for interrogating the right ventricle and overcomes
the uncertainty of the beam pathway and may improve the specificity.
Biventricular hypertrophy, difficult to analyze from ECG recordings,
can be demonstrated dramatically by echocardiography (Fig. 9).