Step-by-Step Approach to Zero Fluoroscopy: Experience at AdventHealth Orlando

EP Lab Digest. 2023;23(2):1,7-9.

Precise anatomical localization is paramount for successful electrophysiology (EP) study and ablation. Intracardiac navigation of catheters has traditionally been performed using fluoroscopy. However, exposure to ionizing radiation is detrimental to both patients and health care providers. For example, for patients undergoing atrial fibrillation (AF) ablation, the effective radiation dose has shown to be equivalent to 830 chest x-rays.¹ The lifetime risk for a fatal malignancy associated with a single AF ablation procedure is estimated to be .15% for women and .21% for men; the risk normalized to 60 minutes of fluoroscopy was .07% for women and .1% for men.¹ For health care providers, the median risk of fatal and nonfatal cancer is calculated at 1 in 192.² Heavy occupational protective equipment also takes a toll. According to a recent survey, 50% of health care professionals using X-ray protective lead attire reported spine problems, while 25% experienced issues related to their hips, ankles, or knees.³

With technological advancements in 3-dimensional (3D) electroanatomic mapping systems and intracardiac echocardiography (ICE), limited and zero fluoroscopy EP study and ablation have emerged as solutions for reducing or eliminating radiation exposure. In 2002, Drago et al first reported fluoroless ablation of right-sided accessory pathways using a single catheter and 3D electroanatomic mapping (Carto system, Biosense Webster, Inc, a Johnson & Johnson company) in pediatric patients.⁴ This technique continues to evolve as experience grows in ICE catheter manipulation and electroanatomic mapping.

Zero fluoroscopy ablation has increasingly become a common practice adopted by centers to address a wide range of arrhythmias. In a single-center retrospective analysis of 1853 procedures reported by Triosi et al from January 2017 to June 2021, the rate of fluoroless procedures increased from 8.5% in 2017 to 22.9% in the first semester of 2021.⁵ In addition, the adoption of a fluoroless approach did not influence procedure time or major complication rate.⁵ A recent meta-analysis summarized 24 studies comparing fluoroscopy-guided vs zero/minimal fluoroscopic ablation to treat paroxysmal supraventricular tachycardia (SVT). In 9047 patients, the short- (risk ratio [RR]=1.00; 95% CI, .99-1.01; P=.97) and long-term success rate (RR=1.01; 95% CI, 1.00-1.03; P=.13) were comparable.⁶ The zero/minimal fluoroscopy group had significantly lower fluoroscopy and ablation times while demonstrating similar complication rates.⁶ In 200 consecutive AF ablations reported by Liu and Palmer, all cases were successfully completed under zero fluoroscopy, with a 76% success rate (mean follow-up of 11 months) and a complication rate of 1%.⁷ Schoene et al also reported using a nonfluoroscopic catheter tracking system for 20 patients undergoing percutaneous cavotricuspid isthmus ablation.⁸ Compared to conventional fluoroscopy ablation, zero fluoroscopy ablation had no difference in efficacy, safety, and procedural duration while achieving a significant reduction in radiation exposure.⁸ For ventricular tachycardia (VT), the feasibility of zero fluoroscopy ablation has been demonstrated to treat VT/premature ventricular contractions (PVCs) originating from the right ventricular outflow tract,⁹ left ventricular summit,¹⁰ and complex congenital disease.¹¹

Electrophysiologists are typically trained to use fluoroscopy as the principal imaging modality, which has potentially hampered the wide adoption of fluoroless ablation. Kochar et al also reported on the learning curve associated with AF, SVT, and PVC ablation using zero fluoroscopy.¹² However, the main hurdle to the adoption of a zero fluoroscopy approach is likely a lack of preparedness to abandon an old practice. Increasing knowledge and experience in this method will facilitate this transition. Herein we share our step-by-step approach to zero fluoroscopy at AdventHealth Orlando.

Zero Fluoroscopy Technique

Fluoroless ablation procedures can safely be performed for all types of arrhythmias, excluding those requiring epicardial access with or without ICE for procedures in the right atrium (RA) and ventricle, or in the left ventricle (LV) using a retrograde approach. For ablations on the left side of the heart, ICE is necessary to guide the transseptal puncture.

Ultrasound-guided vascular access is recommended to avoid accidental puncture of the femoral artery. The number of punctures is dictated by the amount of catheters used during the procedure. A 10 French, 23-cm long sheath is used in more cases to facilitate the advancement of the ICE catheter over the left femoral vein.

Video 1

Video 1. ICE navigation to the IVC and RA, and 3D reconstruction of the RA and CS.

In our approach, an ICE catheter (SoundStar, Biosense Webster, Inc) is first inserted and advanced to the right side of the heart under real-time echocardiographic visualization (Video 1). The catheter is then rotated toward the tricuspid valve and the CartoSound module of the Carto system (Biosense Webster, Inc) is used to create a contour of the ostium of the coronary sinus (CS), which becomes the anatomical reference to advance the next catheter. Other structures can also be delineated with this technique, including but not limited to inferior vena cava (IVC) filters, the valve prosthesis, and aorta (Figure 1). The initial standard views in Carto are right and left anterior oblique projections.

A sensor-based catheter (eg, PentaRay, DecaNav mapping catheter, or SmartTouch 3-mm tip irrigated ablation catheter, Biosense Webster, Inc) is inserted and advanced using tactile feedback to the IVC until it reaches the mapping field, and a matrix and 3D shell of the IVC, superior vena cava (SVC), RA, and CS are created with fast anatomical mapping (FAM) by carefully sweeping the catheter until the His bundle and any other important anatomical landmarks are tagged (Figures 2 and 3, Video 1). Other catheters are then safely advanced to the heart with real-time visualization. When advancing the catheters, attention should be placed to near-field and far-field electrograms to validate contact. The SmartTouch catheter should be calibrated in the RA preferably under ICE visualization to ensure accuracy on contact force. At this time, right-sided ablation can be performed.

For left-sided ablations, transseptal puncture is the most limiting factor for transitioning from near-zero to zero fluoroscopy. The technique requires a good understanding of anatomy and expert use of ICE, which is used to advance to the SVC and rotated posteriorly and inferiorly until the intra-atrial septum and fossa ovalis are in view. A long guidewire is then advanced through one of the right femoral vein introducers until the wire is visualized in the SVC. Once the location of the guidewire is certain, a Carto Vizigo Bi-directional Guiding Sheath (Biosense Webster, Inc) is advanced over the wire until it reaches the SVC. The guidewire is removed and the NRG Transseptal Needle (Baylis Medical) is introduced. The entire apparatus is moved to the fossa ovalis under direct visualization with ICE (Video 2) and with the tip of the dilator directed toward the left pulmonary veins (PVs), the needle is advanced, followed by a puncture of the fossa facilitated with the delivery of radiofrequency application. The needle is then exchanged for the guidewire, which is introduced in the left atrium (LA) and inside one of the left PVs. Under direct visualization of the wire and veins, the transseptal sheath can be safely advanced, and the dilator and wire can be removed (Video 2).

Video 2

Video 2. Steps for completely fluoroless transseptal puncture.

At this time, a weight-based intravenous heparin bolus has been given to the patient (150-200 units per kilogram) and an infusion has been started to maintain an activated clotting time of 350 seconds. For AF ablations, we do not interrupt anticoagulation. In anterior posterior (PA) projection, we bring a PentaRay catheter to the LA and create a 3D shell of the chamber with FAM, followed by a 3D reconstruction of the LV if needed for ablation. A single transseptal technique is typically used, so the PentaRay catheter is exchanged for the SmartTouch ablation catheter once the anatomical geometry has been delineated. When advancing the ablation catheter, special attention is placed to ensure the tip of the transseptal sheath is away from the wall of the LA. It is recommended to slightly withdraw the sheath over the catheter to expose its tip and then calibrate the contact force with the previously described steps (Video 3).

Video 3

Video 3. Safe advancement of the ablation catheter to the LA.

Summary

Fluoroless ablation can be safely performed with the use of ICE and 3D anatomical mapping with a simple stepwise workflow. The routine use of contact force ablation catheters and ICE improve efficacy, reduce the risk of complications, and eliminate exposure to the hazards of radiation. 

Disclosures: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. They have no conflicts of interest to report regarding the content herein.

References

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