4.2 ICE images for evaluation of LAAC
TEE has long been the standard for guiding LAAC. It can exclude LAA
thrombus during the operation, guiding transseptal puncture,
facilitating placement of pigtail, sheath and device, and assessing the
device position and residual flow. Precise assessment of implanted
device position and residual flow was commonly based on optimal
long-axis views of the device displayed by TEE at different imaging
planes. However, limited by the varied anatomical relationship between
the esophagus and the LAA, the long-axis images of the LAA and implanted
device in some patients cannot be displayed satisfactorily, mostly at
135°, which impacts the accuracy in assessing LAA sizing, device
position and residual leakage. The use of ICE has been reported to be
able to obtain sufficient images as TEE to guide LAAC with similar
effectiveness and safety5,6,8,9. In the early studies,
ICE probe was placed in the right atrium, coronary sinus, right
ventricular outflow tract, or pulmonary artery to guide
LAAC2,4,8. However, ICE examination conducted in the
right atrium failed to show consistent optimal images from LA/LAA
because of the inherent far-field limitation. The LAA images obtained
with the ICE probe positioned in LA were dramatically
improved3,5,6,9-11. However, the systematic approach
for manipulating ICE probe to achieve consistent, comparable
multi-angled images as TEE exam was not well described.
Frangieh et al9and Korsholm et al5 did not discuss the detailed
approach to navigate ICE probe in
LAAC. Kim et
al10 placed the ICE probe at a single position in LA
to guide LAAC which might affect assessment accuracy.
Masson et al and Alkhouli et
al3,12 reported using 2 ICE views guide LAAC while
Hemam et al6 went further to show that ICE could be
placed in 4 different positions including the top of LA , the left upper
and lower pulmonary veins, and through the mitral valve to better
evaluate the LAA and the device. But these approaches, without using the
LA geometry map described by us, were limited by the varied anatomical
relationships among LAA, pulmonary veins and mitral valves and the
technical difficulty in acquiring reproducible, comparable and
omni-plane views similar to those obtained by TEE counterparts.
TEE allows to assess the LAA and the device from a full 0-180° sweep of
imaging probe. To compare the performance of ICE versus TEE, we proposed
the step-by-step ”FLAVOR” approach in this study which consistently
obtained high quality, reproducible images at 4 proposed imaging angles.
In our study, all the proposed views could be obtained with good quality
in ICE group. The acquisition of images was independent of
esophageal-LAA anatomical relation which clearly limits the TEE
performance, with more than one-third cases in TEE group were unable to
display the long-axis image at one of the four angles, mostly at 135°.
We suggest that with proper training on the “FLAVOR” approach,
intra-LA ICE imaging could be an attractive alternative for guiding
LAAC. While the cost of ICE catheter remains a barrier limiting its wide
application, it would be appealing for patients undergoing combined AF
ablation and LAAC because the catheter would be needed for transseptal
punctures, LA geometry mapping and guiding ablation anyway.
4.3 The effectiveness of
LAAC with ICE imaging
Previous studies5,6,10 compared the ICE-guided LAAC
under local anesthesia with the TEE-guided LAAC under general
anesthesia, and found that both of them had a very high procedural
success rate. The application of ICE did not reduce the success rate,
nor did it increase device recapture times or resizing rate. Our results
are consistent with these findings, showing LAAC success rate of 100%
for both approaches. Intra-operative residual leak <3mm was
observed in 2 cases in the ICE group and 3 cases in the TEE group after
device release. The device recapture and resizing rates were similar in
the 2 groups. Whether the use of
ICE has a favorable impact on total procedural time, radiation time,
radiation dose and contrast agent dose remained
controversial5,6,9,10. This is largely attributed to
different workflows during the procedure. In contrast to previous
studies, we performed all the procedures under local anesthesia. We
conducted a brief TEE examination only at the end of the procedure to
verify the device position and the degree of residual leak. In ICE
group, we used the LA geometry map to facilitate ICE catheter
manipulation to obtain the optimal imaging plane thereby sparing the
operator the need for intense fluoroscopy control. This approach leads
to reduced fluoroscopy time and radiation exposure without a increase in
procedure time in ICE cohort.