Doppler color flow imaging methods allow for identification of
the presence of certain valvular stenotic jets. There are, however,
no specific characteristics in the color display of stenotic flows
that assist in quantifying the severity of valvular obstruction
at the present time. Spatial location of the direction of a jet
is possible and this may be used to direct a conventional CW Doppler
beam at an optimum angle to flow for precise measurement of peak
velocity data.
Mitral Stenosis
Mitral stenotic jets are characterized by a bright burst of color
from the mitral valve orifice in very early diastole. An instant
later, a central core of aliasing is frequently seen that persists
throughout the remainder of diastole. This appearance has often
been referred to as the "flame-like" pattern of mitral stenosis
and is present in many, but not all, patients with mitral stenosis.
The apical views are clearly the best for recording this characteristic
appearance, as the interrogating beam is nearly parallel to flow
and the best mean velocity estimates are possible.
 |
| Fig.4.37 |
A typical mitral stenotic jet from the apical two-chamber view
is shown in Figure
4.37. Note that a central core of aliasing is less evident
in this jet. Note also that a small jet of aortic insufficiency
is readily separated from the stenotic mitral valve flow.
When a color imaging system contains CW Doppler capabilities,
identification of the direction of the stenotic jet is very helpful
and allows for reasonably precise parallel orientation of a CW
beam with the stenotic jet. This provides a means for operator
interaction between the beam and the jet to assure proper recording
of peak velocities for gradient quantification.
 |
| Fig.4.38 |
There is a demonstration in
Figure 4.38 of the combined use of color flow and CW Doppler
for detection of severe stenosis where the peak transmitral valve
gradient approaches 3 m/s. The pressure half-time is also markedly
delayed in this patient. When using systems equipped with CW capabilities,
the color flow image is automatically frozen when switching into
the conventional mode.
2004