 |
| Fig. 57 |
In cases of
mild pulmonary stenosis, no abnormality is detectable either by
M-mode or two- dimensional echocardiography. With a more severe
obstruction, it may be possible to detect right ventricular hypertrophy,
but echocardiography is not a very sensitive method for diagnosing
this. Another sign that has been reported, but in our experience
is confined to patients with severe obstruction, is an exaggerated
"a-dip" on the pulmonary valve echocardiogram. This arises from
the fact that the hypertrophied right atrium forcefully injects
blood into an already full and stiff right ventricle during atrial
systole. Pulmonary artery pressure is low, and so the sudden increase
in right ventricular pressure is sufficient to partially open the
pulmonary valve (Fig. 57).
 |
| Fig. 58 |
Echocardiography can assist phonocardiography in the diagnosis of
pulmonary valve stenosis by confirming the origin of the early systolic
ejection sound (Fig. 58). A recording showing pulmonary valve closure
may also help confirm the timing of the later pulmonary component
of the second heart sound, although such recordings are routinely
possible only in small children.
Now that Doppler echocardiography is available, it has been shown
to be able to detect, and reliably quantitate, pulmonary stenosis.
2004
