Methods
A novel 9 French 4D ICE catheter (VeriSight Pro®, Philips, Andover, MA)
(Figure 1) was utilized by three different operators, each with
extensive experience with the use of 2D ICE during EP procedures. This
catheter incorporates the same ultrasound technology as a 4D TEE probe,
miniaturized to fit on the tip of a 3.0mm diameter (9 French) catheter.
It has a 90 cm working length with a distal 2 cm imaging tip. The
imaging matrix consists of 840 elements (15 x 56 element design). This
allows for X-plane imaging with live cross-plane 2D imaging. This matrix
also enables 90 x 90 degree volume imaging. The 3D imaging can be
obtained in real time; color Doppler can also be added to the live 3D
imaging. Another feature is digital steering where the catheter is
rotated from the console without the operator moving it manually. There
are two steering knobs on the handle (Figure 1C), one for
anterior-posterior adjustments and the other for right-left adjustments.
There is a separate tension control knob. The articulation segment
allows for a 120-degree deflection range in each direction. The catheter
connects to the Philips EPIQ CVx imaging console, which can also be used
for non-invasive cardiac imaging such as transthoracic echocardiography
and TEE.6 Furthermore, the full spectrum of image
analysis and post-processing available for TEE is available for ICE
imaging including Color Doppler assessment, multiplanar reconstruction
and trans-illumination technology.
The catheter was advanced from the left femoral through a 10 French
short sheath and positioned in various cardiac chambers during ten
interventional EP procedures including catheter ablation and LAAC,
during which a standard 2D ICE catheter would ordinarily be used. All
procedures were guided with fluoroscopy and performed under general
anesthesia. There were no changes to the standard approaches during the
EP procedures because of the use of the 4D ICE catheter. A standard TEE
probe (Philips) was used as well during the LAAC procedures and images
were obtained by the cardiac anesthesiologist. The ICE images were
frozen when the procedure was being guided by TEE, and vice versa to
prevent artifact during imaging.
The ICE catheter was initially placed in the right atrium (RA). Images
were acquired in real time during catheter manipulation by the
electrophysiologist, and processed by a dedicated imaging expert at the
ultrasound console. Initially views were optimized using a standard
0-degree imaging angle using a combination of manual catheter
manipulation and digital steering. In preparation for orthogonal X-plane
imaging, views of the same structures were optimized using a -45-degree
angle so that orthogonal views would be at +45 and -45 degrees. This
approach allowed for better image quality compared to imaging from 0 and
+90-degree angles. In a subset of patients, the ICE catheter was placed
in the LA and in additional positions to assess its ability to acquire
images of the LA and left atrial appendage from other vantage points.
The ICE catheter was placed in the LA by advancing it across the same
transseptal puncture site as the transseptal sheath using a
“shoe-horn” technique without a long sheath.
The VeriSight Pro® 4D ICE catheter is approved for use in humans by the
United States Food and Drug Administration (FDA). Procedures were
performed after FDA approval, in preparation for a planned registry
study that has been approved by the Northwestern Institutional Review
Board (IRB) and is sponsored by Philips, the manufacturer of the 4D ICE
catheter.