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Atrial fibrillation (AF) is the single most common heart rhythm disturbance in adult humans, affecting over 2.5 million people in the United States alone.1 While numerous treatment options have been developed for rate control, stroke prevention, and pharmacologic suppression, ablative therapy remains an attractive option for patients when less-invasive treatments are ineffective or poorly tolerated. Radiofrequency catheter ablation (RFCA) has been available and reported for 20 years. As mapping and catheter technologies have become refined, more advanced AF cases have been considered for RFCA, resulting in an increase in procedure complexity and duration. As fluoroscopy use has traditionally been a material necessity in the performance of electrophysiology procedures, radiation exposure for patients as well as laboratory staff increases in tandem with procedure complexity and duration.² With improvements to commercially available mapping systems and augmented use of intracardiac echocardiography (ICE), it has become possible, if not preferable, to replace fluoroscopy-based imaging with mapping and ICE imaging modalities to perform AF ablation.^3–11

Required Equipment

While fluoroscopic imaging only provides direct tissue information limited to cardiac silhouette with some superimposed chamber shadowing, it does provide real-time, nearly instantaneous imaging of intracardiac catheters as they move within the vasculature and heart chambers. To safely and effectively perform these maneuvers without fluoroscopy requires the mastery of alternative imaging systems that provide information equal or superior to standard fluoroscopy. For this reason, a 3-dimensional (3D) mapping system with high spatial accuracy and minimal latency is required along with ICE imaging, ideally with the ability to import echocardiographic image contours directly into the mapping display environment. At the time current time, only the CARTO3 mapping system (Biosense Webster, Diamond Bar, CA) in conjunction with CARTOSOUND has the spatial accuracy and latency to offer a suitable replacement to fluoroscopy. The use of a contact force-sensing catheter is recommended as this provides numerical force-sensing information superior to fluoroscopic or tactile feedback information alone. Additional experience using transcutaneous ultrasound imaging probes for groin access and wire advancement are helpful; these probes usually come standard with most ICE imaging systems. The use of an esophageal temperature probe, a standard safety feature in many labs, is modified by placing a sensored catheter into the probe lumen such that the sensor is directly adjacent to the thermocouple (Figure 31.1). Finally, the use of a blunt radiofrequency (RF) needle (Baylis Medical, Toronto, Ontario, Canada) is recommended to be able to safely obtain transseptal access.

Preprocedure Preparation

The patient is brought to the electrophysiology lab in the usual fasting state with uninterrupted anticoagulation. CARTO patches are applied in the standard chest and back locations. After sedation (usually general anesthesia with endotracheal intubation), the esophageal probe/sensored catheter combination is placed in the oropharynx and advanced into the mid to distal esophagus. This sensored catheter can now be seen in the CARTO mapping screen, marking the location of the adjacent esophageal probe. To visualize the transseptal needle, 2 pinned cables are placed in a dedicated pin block (Figure 31.2): the distal cable is connected directly to a junction box (Baylis Medical), which includes a manual switch between electrode tip visualization in the mapping system and RF energy delivery for the transseptal needle; the proximal cable is connected in a piggy-back fashion into the pin block used for the duo-decapolar catheter, to use the proximal coronary sinus (CS) as the reference electrode. The patient is then prepped in the groin and subxiphoid areas as would be standard in a fluoroscopic case.

Procedure

Using a transcutaneous linear ultrasound probe, the femoral artery and vein are imaged, carefully noting the bifurcation of the profundus branch of the femoral artery from the main femoral artery. Access needle placement into the femoral vein, taking care not to enter any superficial arterioles, should be done just proximal to the femoral artery bifurcation. Access is obtained twice into both the right and left femoral veins. Upon venous cannulation, guidewires are advanced. Rotating the linear ultrasound probe 90° allows for a longitudinal view of the vein and confirms that the wires are advancing cranially (Figure 31.3). If suture closure upon sheath removal is planned, this is the best tie to place a figure-8 silk suture. This is performed by using an 0 silk with a large, curved needle (e.g., CT-1, Ethicon). The proximal or cranial skin bite should be large and proximal to the actual entry point into the vein as imaged with the linear probe. The distal skin bite is less critical and serves more like an anchor for the proximal suture bite. If performed properly, this suture is pulled tight enough to prevent visible bleeding and uses the patient’s own superficial fascia to apply the pressure needed for hemostasis.¹² Electronic Short sheaths are advanced over the wire, and the dilators and wires are removed. After flushing of all sheaths, an ICE catheter is inserted into one of the left venous access sheaths and advanced slowly, deflecting the tip if necessary to reach the bifurcation of the iliac vein branches from the inferior vena cava (IVC) (Figure 31.4). If resistance is felt with ICE probe advancement, pull back gently and note the direction of microbubble flow in the ICE imaging window and follow that path. Advance long sheath wires into the remaining short sheaths and observe each wire advance past the iliac bifurcation and up into the IVC. Except for the ICE sheath, replace each of the short sheaths with long sheaths to help eliminate the possibility of catheters becoming any side branching veins of the IVC. The two sheaths in the right femoral vein are specifically replaced by sheaths suitable for transseptal access.

The ICE catheter is then advanced into the right atrium (RA) using imaging from the ICE catheter itself to assist ( Video 31.1). A sound contour is obtained of the aortic root, the os of the CS, and the fossa ovalis (Figure 31.5). After connecting the ablation catheter to the mapping system, the catheter is advanced through one of the sheaths in the right groin and advanced into the RA while observing the catheter position in the mapping window. At this point, the aortic valve and CS contours are visible, as well as the sensored catheter in the esophagus representing temperature probe position. Because the His bundle recording rests just caudal to the aortic valve, the aortic valve contour is used to locate the His bundle. The mapping catheter is then withdrawn into the RA and advanced into the superior vena cava (SVC). The remaining right groin sheath is then used to advance a sensored multi-electrode mapping catheter (either Lasso or PENTARAY, Biosense Webstrer). Between the ablation and the multi-electrode catheter, a detailed geometry of the RA and CS are created (Figure 31.6). Using the advanced catheter location (ACL) system, nonsensored catheters may be visualized in the mapping environment accurately, but only after creating and adequate ACL computer matrix. Inadequate ACL matrix is usually the reason that nonsensored catheter are not seen or flash in and out of visibility in the mapping screen. To address this, matrix may be displayed directly to confirm its adequacy in the desired chambers (Figure 31.6). Once created, a decapolar or duo-decapolar nonsensored catheter is advanced into the remaining left groin sheath. Normally, nonsensored catheters can only be visualized when all electrodes are advanced out of the sheath. To overcome this problem, each electrode may be visualized individually if the raw data feature is temporarily turned on. This allows for advance of the duo-decapolar catheter into the CS while a portion remains in the sheath (Figure 31.7). Upon CS cannulation, the remainder of the catheter is advanced along the free wall of the RA and the entire catheter may be visualized without the raw data feature (Figure 31.7).

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