GE Vivid S70, User Manual

Page: 269 / 709

Quantitative TVI Stress echo analysis
Vivid S70 / S60
–
User Manual
7-21
BC092760-1EN 01
Society of Echocardiography 16 segments model. However, the
velocity cutoff model does not cover the apical segments (due to
low velocities and segment orientation), (see note).
NOTE: Velocity measurements in mid and basal segments of the
myocardium will contain contributions from the apical region of
the myocardium. E.g. if measured value in a mid segment is
below the cutoff value for this segment then this might relate to a
reduced function in the mid or apical region.
Tissue Doppler does not have perfect site-specificity because of
tethering by adjacent segments. Thus, although an ischemic
segment has little thickening (and therefore could be expected
to show low velocity), measured velocity may be influenced by
local tethering, reflecting contraction in surrounding segments.
Conversely, a normal segment may have its velocity reduced by
an adjacent segment with reduced velocity. This tethering effect
may decrease the sensitivity for single vessel disease, but
nonetheless the sensitivity and specificity of the cut-offs are
approximately 80% (see reference 1 on page 7-25).
Three different analysis tools based on TVI data are available:
• ‘Vpeak measurement’ on
page 7-22
, enables the display
of a tissue velocity trace for a selected region of a previously
scored segment through the entire heart cycle. In addition
Vpeak is color-coded on the 2D image. From the velocity
trace, the user can estimate the peak systolic velocity (see
reference 1 on page 7-25).
This tool is available in views from peak levels only and only
when a segment has been scored in one of these views.
• ‘Tissue Tracking’ on
page 7-25
, enables visualization of
the systolic contraction of the heart by color-coding the
myocardial displacement through the systole.
• ‘Quantitative analysis’ on
page 7-25
, enables further
quantitative analysis based on multiple tissue velocity
traces.
The quantitative analysis is described in Chapter
‘Quantitative Analysis’ on
page 9-1
.