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Implementing a No-Blind-Spot Approach to Zero Fluoroscopy Catheter Ablation of Atrial Fibrillation
© 2023 HMP Global. All Rights Reserved.
Any views and opinions expressed are those of the author(s) and/or participants and do not necessarily reflect the views, policy, or position of EP Lab Digest or HMP Global, their employees, and affiliates.
EP LAB DIGEST. 2023;23(10):1,8-11.
On a full moon on Friday the 13th in September 2019, a previously healthy 24-year-old pregnant woman presented to our emergency department with incessant atrial tachycardia associated with congestive heart failure. Echocardiogram estimated left ventricular ejection fraction (LVEF) at 15%-20%. After more than 3 hours of maximum unsuccessful efforts to restore and maintain sinus rhythm, including using different intravenous (IV) antiarrhythmics and external cardioversions, the patient developed hypotension and showed signs of fetal distress.
The patient was taken emergently to the electrophysiology laboratory and underwent successful fluoroless radiofrequency (RF) ablation of a focal coronary sinus os (CS) atrial tachycardia. Avoiding fluoroscopy helped alleviate the concerns of potential harm to the fetus. Signs of fetal distress resolved almost immediately, and LVEF improved to 35% on repeat echocardiogram the following day and later recovered. The patient completed her pregnancy and delivered a healthy baby.
While cases of fluoroless ablation during pregnancy have already been well described in the literature, we share this case in an effort to highlight our path to achieving complete fluoroless access and discuss our tips for implementation. The use of fluoroscopy has been an essential part of ablation procedures. Ionizing radiation exposure poses potentially significant risks to the patient, the fetus, the operator, and other team members.1 These risks are mostly but not entirely mitigated by taking different measures, including wearing a protective lead shield, which has its occupational hazards.2 Minimal or zero fluoroscopy catheter ablation (ZFCA) has been increasingly adopted when performing ablation procedures.
However, the transition to ZFCA is often associated with concerns about anxiety and safety. These issues are mainly related to steps being performed without the confidence of fluoroscopic monitoring and, as a result, having potential blind spots. Our journey to ZFCA started 6 years ago, and we have developed an effective, no-blind-spot workflow that we share in this article.
The following is a step-by-step guide to performing ZFCA for atrial fibrillation (AF) using an intracardiac echocardiography (ICE) catheter (SoundStar, Biosense Webster, Inc, a Johnson & Johnson company) and 3-dimensional (3D) electroanatomic mapping system (Carto 3, Biosense Webster). We aim to present enough detailed information, figures, and videos to help guide others to confidently implement ZFCA for AF.
Our current ZFCA workflow can be divided into 5 main steps:
1. Venous access
2. ICE catheter anatomic reconstruction
3. Ablation catheter matrix creation
4. Transseptal puncture
5. Mapping and ablation
Step 1: Venous Access
Our approach to AF ablation has evolved over the years, and now requires only 2 venous sheaths and 1 transseptal puncture.3 We uniformly use ultrasound to guide femoral venous access. After obtaining venous access, 2 guidewires are advanced into the femoral vein. If resistance is encountered, the guidewire is moved gently back and forth and rotated until a smooth advancement is achieved. A long 25-cm sheath is then advanced with its dilator over the guidewire (the caudal of the two). This sheath is used to advance the ICE catheter. The other guidewire is used later to advance the SL1 sheath (Abbott). IV heparin bolus at a dose of about 150 units/kg is administered before or immediately after obtaining vascular access. Activated clotting time is checked via the side arm of the ICE sheath every 15-20 minutes with a goal level of 350 seconds or higher (Video 1).
Step 2: ICE Catheter Anatomic Reconstruction
Our purpose is the following:
• Confirmation of the presence of SL1 sheath guidewire in the IVC to safely advance the SL1 sheath into the IVC.
• Anatomic delineation of the inferior vena cava (IVC), aortic root, CS, cavotricuspid isthmus (CTI), mid fossa ovalis (FO), left atrium (LA), left atrium appendage (LAA) and pulmonary veins (PVs), superior vena cava (SVC), and delineation of the right phrenic nerve (PN).
Proficiency in ICE catheter manipulation and image interpretation is essential for implementing ZFCA. More detailed instructions are beyond the scope of this article.
The ICE catheter is advanced up the IVC until its tip appears in the Carto field. From that point on, all structures encountered can be outlined and reconstructed by the Carto system. The IVC wall is traced as the ICE catheter is advanced toward the RA. While in the IVC, the ICE catheter is rotated as needed to confirm the presence of the SL1 sheath guidewire in the IVC. The SL1 sheath is then safely advanced over the guidewire into the IVC level.
Once in the RA, the ICE catheter is placed in the “home view.” A clockwise rotation will allow visualization and outlining of the aortic root, CTI line, CS, LA, LAA, and left PVs. A posterior curve and a right turn of the ICE catheter allow better visualization of the FO and SVC. The mid fossa point is tagged to be targeted by the transseptal needle. The ICE catheter is advanced into the SVC. Clockwise rotation of the catheter in the SVC enables visualization of the right PVs, and further clockwise rotation will outline the right PN as a highly echogenic linear structure (Video 2).
At the end of this step, we will have all relevant anatomical structures identified and reconstructed (Figure 1).
Step 3: Ablation Catheter Matrix Creation
In this step, our purpose is for:
• Matrix creation in the IVC, CS, right atrium (RA), and SVC to visualize the tip of the transseptal needle while performing transseptal puncture and to visualize, advance, and place the duodecapolar catheter in the RA/CS.
• Safe delivery of the SL1 sheath over the ablation catheter into the SVC.
Once ICE confirms the presence of the SL1 sheath guidewire in the IVC, the sheath with its dilator is advanced over the guidewire to the IVC level. The dilator and guidewire are then removed, and a contact force irrigated tip ablation catheter (ThermoCool SmartTouch, Biosense Webster) is advanced through the sheath. After the tip of the ablation catheter exits the sheath (denoted by the change in the color of the ring electrodes from black to gray) (Figure 2), the catheter’s contact force sensor is zeroed. The catheter is then slowly advanced up the IVC and into the RA while building the matrix in the IVC, then in the RA, and within the CS. Catheter advancement is guided by the Carto mapping system, contact force, and the anatomic road map created by ICE. The His potential recording site is tagged. For non-Nav catheters to be reliably visualized, the matrix needs to be built relatively slowly until the grid in the areas of interest turns green. After that, the ablation catheter is advanced and placed in the SVC (Figure 3). The sheath is advanced over the catheter to cover its tip (tip electrode color changes from gray to black). The ablation catheter is then removed, leaving the SL1 sheath in the SVC (Video 3).
Step 4: Transseptal Puncture
With the SL1 sheath in the SVC, the transseptal puncture needle (Baylis Medical) is advanced into the SL1 sheath dilator outside the body until the tip of the needle reaches the tip of the dilator without protruding. The back end of the needle is connected to the RF/mapping system and a pressure recording line. The needle and dilator are advanced into the SL1 sheath while maintaining the needle just at the tip of the dilator. Once the tip of the dilator reaches the tip of the sheath in the SVC, the sheath is pulled back over the dilator to passively expose the dilator; the dilator is then pulled back over the needle to passively expose the tip of the needle. Once exposed, the needle tip becomes visible in the Carto matrix field.
The sheath/dilator/needle assembly is then pulled down in left anterior oblique (LAO) and right anterior oblique (RAO) views targeting the mid fossa point with the tip of the needle and under ICE monitoring of the interatrial septum (IAS). Once the needle tip reaches the mid fossa and IAS tenting is confirmed by ICE, RF energy is applied for one second to cross the septum. LA pressure waveform and saline injection (microbubbles) confirm LA access. The dilator is then advanced over the needle while holding it in place (the needle tip becomes invisible in the Carto field once covered by the dilator). The sheath is advanced over the dilator while holding the dilator in place. The needle and dilator are then removed, leaving the tip of the SL1 sheath in the LA.
Another option, after its initial crossing of the IAS, is the needle could be exchanged with a coil guidewire (Torayguide, Toray Group) over which the SL1 sheath and its dilator can be advanced further into the LA. This approach is advisable early in the implementation process of ZFCA or in case of difficulty visualizing the LA (thick or echogenic IAS septum) or resistance advancing the sheath across the IAS. The large terminal coil of Torayguide allows for much easier detection by ICE compared to a J guidewire. If it is difficult to detect the coil within the LA, it is likely that it crossed the mitral valve to the left ventricle.
After successful transseptal puncture, the body of the SL1 sheath at the point of IAS crossing is outlined using Cartosound. This will guide ablation catheter reentry into the LA if needed (Video 4).
Step 5: Mapping and Ablation
A high-density recording catheter (PentaRay Nav, Biosense Webster) is advanced through the SL1 sheath into the LA. The color of the catheter tip ring electrode changes from black to gray once outside the sheath. After creating the LA 3D and voltage map, the PentaRay catheter is exchanged with the ablation catheter. The ablation catheter is advanced into the LA, relying on a change in ring electrode color from black to gray once it exits the sheath. With the catheter tip free from tissue contact, the catheter contact force sensor is zeroed again. Pacing from the ablation catheter at maximum output is performed in the right PV area to identify PN stimulation sites to avoid when isolating the right PVs. After that, ablation is performed targeting PV isolation and other areas individualized to each patient.
A single-sensor probe (Esophageal Stethoscope, DeRoyal Industries Inc) is used to monitor esophageal temperature. A quadripolar diagnostic catheter is securely tied to the probe’s tip and then connected to the Carto system to allow intraoperative monitoring and adjustment of its position (Figure 4, Video 5).
At any time during the procedure, the ICE catheter could be exchanged with the duodecapolar catheter (Abbott). The long 25-cm ICE sheath, with its tip in the IVC, allows easy advancement of the duodecapolar catheter without the need to maneuver it within the pelvic veins. The existing matrix helps visualize and advance the catheter into the RA and allows its manipulation within the RA to place it along the tricuspid annulus with the distal portion in the CS (Figure 5, Video 6).
At the end of the procedure, IV protamine sulfate is administered and hemostasis is achieved using a closure device.
Essential Considerations for Implementation
We need to stress the importance of proficiency in ICE catheter use and recommend the implementation process to be gradual and stepwise over a few weeks to a few months. We recommend visiting a few EP laboratories to observe their fluoroless workflow and appreciate their slightly different steps and tools before starting your own. One suggestion is to practice minimal to zero fluoroscopy after performing transseptal procedures while maintaining the existing workflow. After that, one step could be adopted and repeated until achieving the needed level of confidence and safety. Another step could be added until the full implementation of ZFCA protocol. There should be no hesitation in using fluoroscopy whenever in doubt. This will ensure safe implementation. Close working relationships with vendors and support staff are essential to developing a consistent, efficient, and safe workflow.
Procedure Data
A review of the last 100 AF ablation cases, including paroxysmal and persistent AF, performed by a single operator showed an average time of 17 minutes between vascular access and successful transseptal puncture and an average procedure time of 84 minutes calculated between the time of vascular access and the time of achievement of groin hemostasis. There was no cardiac perforation or other major complications.
Summary
Implementing ZFCA protocols using ICE and 3D electroanatomic mapping helps avoid the risks related to radiation exposure. The implementation process should be gradual and requires proficiency in ICE and a close working relationship with the mapping system representative and staff members. Once established, ZFCA workflow is not expected to result in longer procedure times or higher complication rates. n
Acknowledgement. We are thankful to Kelsey Cook, Senior Clinical Account Specialist III, Biosense Webster, for her help in developing our current zero fluoroscopy workflow.
Disclosure: The author has completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Alsheikh reports no conflicts of interest regarding the content herein.
References
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2. Jiang R, Chen M, Liu Q, et al. Body pain - an unheeded personal health hazard in interventional cardiologists: a national online cross-sectional survey study in China. Int J Cardiol. 2022;350:27-32. doi:10.1016/j.ijcard.2021.12.052
3. Verma S, Giedrimas E, Hernandez N, Alsheikh T. Same-day discharge for EP procedures: update from the Baptist Heart and Vascular Institute. EP Lab Digest. 2021;21(8):1,8-9.
