Representative Intraprocedural Images
Figure 2A shows a fluoroscopic image of the ICE catheter in the RA while a pulmonary venogram is performed. The ICE catheter was subsequently advanced and positioned in the LA and the left superior PV (Figure 2B). The appendage was also visualized from lower in the LA (Figure 2C), from the right ventricular outflow tract and pulmonary artery, and from the coronary sinus (Figure 2D).
As with 2D ICE, imaging was initially performed of the tricuspid valve, RA, and right ventricle from the “home view” (Figure 3A). Clockwise rotation of the catheter brought into view the aorta, the left ventricle, mitral valve, and the interatrial septum (Figure 3 – online video). The interatrial septum was clearly visualized in both 2D and 3D (Figure 3B). In Figure 3C, images from the home view in a patient with a prominent moderator band in the right ventricle are shown in 2D and 3D.
As with 3D TEE, volumetric imaging with the novel ICE catheter requires an optimized 2D image. An example of a transseptal catheterization is shown in Figure 4. In panel A, a standard 2D ICE view of the interatrial septum is shown with the needle tenting alongside the 3D reconstruction of the same view. In Figure 4B, a sheath can be seen after it was advanced across the septum. One patient undergoing cryoballoon ablation had a 18 mm atrial septal occluder in place (Amplatzer, Abbott, Plymouth, MN) that had been implanted almost two decades earlier. A 2D ICE image of the interatrial septum demonstrates the sheath inferior to the closure device (Figure 4C). In panel D, a 3D image of the cryoballoon sheath crossing the septum beneath the closure device is shown.
In one patient who underwent radiofrequency ablation, the catheter tip electrode was visualized on the posterior wall. Figure 5 shows the 2D cross sections of the image, where the hyperechoic tissue from ablation is noted as well as the 3D reconstruction. On video recording (Figure 5 online), the saline bubbles from irrigation can be visualized.
Cryoballoon ablation was performed in seven of the patients. In Figure 6A, the cryoballoon is visualized in the left superior PV in 2D. Another unique feature of the 4D ICE system is the ability to digitally steer the volumetric images from the console. In doing so, images such as those shown in Figure 6B can be obtained, showing an en-face view of the cryoballoon in the left superior PV. Color Doppler was added to this image as shown in panel C, demonstrating a leak around the balloon. The ICE catheter was also advanced into the LA and Figure 6D shows the balloon after warming and deflating (online video Figure 6D). The cryoballoon itself could be seen well with 2D and 4D imaging, but it was difficult to image past or through the cryoballoon due to reflections from the balloon.
Pulsed field ablation was performed in one patient using the PulseSelect system (Medtronic), which involves a circular shaped ablation catheter with multiple gold ablation electrodes. Images of this investigational catheter in the left superior PV and LA are shown in Figure 7 (panels A and B, respectively). Irrigation from the catheter in the left superior PV can be seen in the online video.
Because of the ability to place the ICE catheter in various locations closer to the left atrial appendage, visualization during LAAC procedures has improved. Figure 8A demonstrates a 3D image of an implanted LAAC device, obtained from the LA. From the LA, views can be obtained to measure the mitral shoulder after device deployment. This is shown in Figure 8B using the glass view feature. Lastly, the ICE catheter can be withdrawn from the LA and advanced into the coronary sinus to visualize the closure device in the left atrial appendage (Figure 8C).