Intracardiac echocardiography, electroanatomical mapping, and the obsolescence of fluoroscopy for catheter ablation procedures

With fluoroscopic guidance being the traditional approach, forgoing the use of fluoroscopy was initially met with safety concerns. However, performing a zero-fluoro ablation is different from just performing a fluoroscopically guided ablation without fluoroscopy. Every step of the procedure, from femoral venous access, to approaching the heart, to transseptal puncture, to delivery of ablation lesions, is guided by either (or both) EAM or ICE.

For femoral venous access, the handheld ultrasound can trace the J-wire cephalad, verifying venous placement and a course toward the heart. The entire journey from the femoral vein to the heart can be guided by ICE, maneuvering to preserve the echolucent space while ascending. If a branch vessel is engaged, the catheter can be partly withdrawn and either anteflexed or retroflexed to take the alternate path that leads to the heart.

Zero-fluoro transseptal is generally performed through one of two approaches [2]. ICE can be used to guide the wire to the SVC, followed by a traditional drawing down of sheath and dilator toward the septum. Alternatively, the ablator can be advanced through the transseptal sheath and positioned at the septum. The sheath can then ride the ablator as a rail and come to rest on the septum, followed by advancement of the dilator and subsequent unsheathing of the dilator at the septum for puncture. Both of these approaches can be learned and incorporated into an ablation workflow, and, once mastered, they can be performed just as quickly as a traditional fluoroscopic approach.

As operators become more facile with ICE, though the initial motivation may have been to facilitate zero-fluoro ablation, those skills transfer and make the entire procedure safer. For example, expert operators may routinely use ICE to rule out left atrial appendage thrombus through imaging from the left pulmonary artery. Comfort and skill with using ICE also permit real-time observation of ablation lesion delivery, allowing direct visualization of the tissue effect of ablation, as the tissue becomes progressively more echo-bright. Direct observation with ICE also removes any ambiguity that might remain when the 3D EAM system has difficulty resolving the location of the catheter between two closely related structures, such as the left superior pulmonary vein and the left atrial appendage.

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