 |
| Fig.2.8 |
Almost all
of the studies into the validation of Doppler detection of valvular
regurgitation have been in comparison to cineangiography. Aside
from physical examination, it is the only currently available clinical
method for the detection of valvular regurgitation. Despite the
present enthusiasm and interest concerning Doppler methodology,
the beginner should understand the fundamental differences between
these two approaches. It is unlikely that the results of Doppler
and cineangiography will ever correlate exactly because the two
methods are so fundamentally different in the presentation of data
concerning valvular regurgitation. Cineangiography, of course, requires
invasive cardiac catheterization and is based upon the dilution
of injected radio-opaque contrast on the final X-ray image. However,
this catheterization based method is not an ideal "gold standard".
When small regurgitant jets are directed into enlarged chambers
the resulting dilution of the angiographic contrast agent may render
the regurgitation undetectable. Small degrees of regurgitation by
angiography may also be highly dependent upon precise catheter location.
Angiographic evaluation of right sided lesions is particularly difficult,
since catheters must be placed across the valve being evaluated
causing at least some degree of catheter induced insufficiency (Fig.
2.8).
Furthermore, the angiographic grading scheme for insufficiency used
in most catheterization laboratories (0 to 4+) is based on subjective
interpretation as contrast progressively opacifies a receiving chamber
over several heart beats. There is general agreement that this method
for estimation of severity is subject to considerable interpretive
errors as a result.
2004