It is also
important to remember that most Doppler-angiographic comparisons
have involved relatively small numbers of catheterized patients
and, in some cases, the criteria for patient selection have not
been specifically stated. Almost all studies have involved patients
with sufficiency disease of the valve to warrant catheterization,
and the very favorable results reported might not apply to larger
groups of patients with less advanced disease. Some studies have
even included Doppler evaluations performed after the angiogram
by operators who have been influenced by the angiographic results.
Given the limitations of these techniques, in our institution Doppler
angiographic comparisons yield a sensitivity and specificity approach
100% when significant (2+ or greater) angiographic regurgitation
is present. When there is little or no angiographic regurgitation
(1+ or 0), the two techniques are somewhat less likely to agree.
As we shall see, Doppler may detect the presence of valvular regurgitation
in patients without any evidence of a cardiac murmur. In fact, there
are surprisingly high rates of detectable lesions such as tricuspid
and pulmonic insufficiencies in normal patients. In our laboratory,
tricuspid regurgitation is found in 38% of normal healthy young
volunteers, while mitral regurgitation is found in 23%, pulmonic
regurgitation in 8%, and aortic regurgitation in 8%. Most regurgitations
in this series were judged as minor.
This seemingly high prevalence of valvular regurgitation may surprise
clinicians experienced with cardiac auscultation. In each case,
no murmurs were heard or recorded by phonocardiography. These findings
serve to highlight two important points.
First, careful Doppler examinations may reveal trivial regurgitations
that are not heard by common auscultatory techniques. Clinicians
who use Doppler echocardiography generally accept that small degrees
of valvular regurgitation may occur in otherwise normal individuals.
Second, auscultatory events are the audible result of valvular regurgitation.
Doppler events are the electronic phase shift result of the same
regurgitation. These are two fundamentally different ways of measuring
the same event. The sound emitted from a Doppler instrument is not
the same as that heard through a stethoscope and beginners should
not expect the two to be the same.
As a consequence of all these factors, it must be recognized that
exact correlations between methods will never exist. Experienced
Doppler operators will detect regurgitant jets which cannot be documented
by angiography and may also miss some small jets recognized by angiographic
methods. It is clearly best for beginners to Doppler echocardiography
to perform some Doppler-angiographic comparisons of their own in
order to establish the level of reliability in their own laboratories.
Similarly, clinical correlations of Doppler with auscultatory findings
will rarely be identical.
2004