The SANS FLUORO Approach to Ablation

Fluoroscopy reduction to the point of elimination is a growing trend in the EP community. Yet despite the increasing number of original research articles and case studies on different zero fluoroscopy or lead-free techniques being published, only a small percentage of all EP labs are fluoroless.

Working in the EP lab can be hazardous — physicians, nurses, and technicians can accumulate large amounts of fluoroscopic radiation exposure over time,^1,2 and prolonged protective lead apron use may result in a significant risk for orthopedic issues.³ Patients can also be unnecessarily exposed to radiation exposure.⁴ In the past, patients might receive up to 60 mSv of absorbed radiation during an ablation procedure; the annual exposure for a cardiac electrophysiologist was approximately 5 mSv.¹⁸ While almost all operators and staff are aware of the ALARA (As Low As Reasonably Achievable) principle, there is still no amount of radiation that is completely safe with both deterministic and stochastic effects.^5,6

Fluoroless techniques have been used in pediatric and pregnant populations, but only recently have gained traction in the adult population.^7-11 Therefore, for those of us who work in electrophysiology, many consider fluoroscopy a necessary evil. Simply put: it is not! Many fluoroless techniques have been described elsewhere¹⁶; in this article, we briefly review our SANS FLUORO technique.

Description of Approach

In 2016, we published our initial experience with zero fluoroscopy ablation in predominantly persistent atrial fibrillation patients.¹² Since that time, we have performed almost 1000 ablations SANS FLUORO — this includes simple AV node ablation to typical flutter, to most SVT cases including AVNRT, AVRT, as well as atrial tachycardias (AT). All ablations are performed without fluoroscopy, including both radiofrequency (RF) and cryo ablations for patients with atrial fibrillation. We do not currently perform epicardial ablations, which would likely require x-ray for catheter/wire verifications; however, all endocardial ventricular tachycardia (VT) and PVC cases are fluoroless. Approximately 5 seconds of fluoroscopy is required to register remote magnetic catheter navigation technology (RMT).

A learning curve does exist for EP operators to go fluoroless, but it is not insurmountable. For example, I performed my first “no fluoro” ablation only six months after completing EP fellowship. An in-depth understanding of cardiac anatomy, especially the chamber of interest, as well as high-level ICE utilization, are critical.^13,14 Initially, atrial fibrillation ablations utilizing RF are probably the easiest place to begin. Most EPs already depend heavily on mapping systems during PVI, so the crucial first step is to learn to perform the transseptal puncture with ICE alone. I would then recommend trying right-sided SVTs and PVCs, and then finally, VT cases may be achieved. Most importantly, one should continuously evaluate the electrograms to confirm that they are “where they think they are.”

Mapping systems have made dramatic improvements that allow zero fluoroscopy techniques to be performed. Current systems approach CT quality with their definition capabilities, with spatial resolution down to 1-2 mm.¹⁵ All three major mapping systems (EnSite Precision Cardiac Mapping System, Abbott; CARTO 3 System, Biosense Webster, Inc., a Johnson & Johnson company; and RHYTHMIA HDx Mapping System, Boston Scientific) can be utilized successfully. In our lab, the CARTO system was initially used. However, there are also advantages in using a system with an open platform — an initial map can be made very quickly with any CS catheter (duo or decapolar), which is frequently the first catheter placed in most ablations.

When performing the SANS FLUORO technique, the following steps can be used. After obtaining femoral vein access with short sheaths, a decapolar CS catheter is advanced to the level of the right atrium (RA). Monitoring electrograms for atrial signal will inform the operator when the catheter is in the RA, right ventricle (RV), coronary sinus (CS), and His. An anatomic shell of the RA, SVC, and IVC with identification of the His is then made. If a cavotricuspid isthmus (CTI) is anticipated for a typical flutter, the RV-RA annulus and the CTI are mapped more extensively. Finally, the coronary sinus is cannulated. Other catheters are then placed, depending on the clinical arrhythmia. When performing left-sided cases, short sheaths are exchanged for longer ones and ICE assistance is used for transseptal puncture.

For most SVT cases, especially AVNRT, after placement of the CS, three diagnostic (usually Josephson) catheters are placed (RA, RV, and His), and the EP study is commenced. Post induction and pacing maneuvers, the His catheter is removed and replaced with an ablation catheter. The critical step is to always re-identify the His. This step is performed multiple times during the ablation to prevent damage to the fast pathway, and corrects map drift and impedance distortion. Frequently, re-identifying the os of the CS is also helpful. Ablation of the slow pathway is then performed (Figure 1).

If AVRT is present and a left-sided pathway is targeted, an ICE catheter is placed and used for transseptal crossing. A recent example of typical AVNRT in combination with a concealed left-sided anterior lateral pathway is shown in Figure 2 and Video 1.

In cases of typical RA flutter, only two catheters are commonly used: the CS (as above), and an ablation catheter. A His cloud is made to denote its location as well as points to demarcate the annulus and IVC. Again, reliance on electrogram signal and evaluating impedance is key to knowing exact location. A recent 540-lb patient (BMI of 72) with atrial flutter was ablated SANS FLUORO (Figure 3). She was too heavy for the x-ray table, so the procedure had to be performed in a bariatric bed. Use of sensor enabled (magnetic) catheters and force sensing ablation catheters can also be helpful with this type of ablation. Super obese patients receive exceedingly greater amounts of absorbed radiation despite best efforts to reduce exposure¹⁷; however, fluoroless techniques eliminate this issue.   

VT and PVC ablations are also tailored to the chamber of interest. Outflow tract ablations are performed with a typical three-step mapping process. Commonly, we use RMT to decrease the perforation risk. The RMT catheter is used with a long sheath to create a matrix using the CARTO system in order to visualize other catheters as well. The RV catheter is then placed, and the RVOT is mapped first. If necessary, this is followed by mapping the CS, being careful to use impedance for guidance as well. If the PVC originates from the LVOT or cusp, transseptal puncture is performed with ICE (or a retrograde aortic approach is used).

Ischemic VT or scar-based endocardial ablations are performed manually or with RMT. If performed manually, use of high-density grid mapping (Advisor^™ HD Grid Mapping Catheter, Sensor Enabled^™, Abbott) or other multi-splined/electrode catheter allows rapid acquisition of points. Retrograde access may be less time-consuming, but there can be some pitfalls. An example of a scar-based VT ablation is shown with an atretic, completely occluded saphenous vein graft. (Figure 4)

In atrial fibrillation cases, PVI can be similarly performed. A right atrium shell is created with the CS catheter and then placed into the CS. Next, a long sheath is placed in the IVC, and a high-density grid mapping catheter is advanced to the SVC. This is confirmed on a three-dimensional map as well as by the loss of electrograms. ICE is used to evaluate the left atrial appendage for thrombus, and transseptal puncture is performed with the “aim” toward the left veins to prevent the crossing from being excessively posterior. Next, the LA is again mapped extensively with ICE guidance. Most commonly, a single transseptal approach is used. High-quality ICE removes the pre-procedure CT guidance for PV anatomy. Contact force sensing RF catheters are critical for success in this area. Use of contact force, force-time integral (FTI), lesion size index (LSI), and impedance drops as well as electrogram attenuation are all incorporated to evaluate the individual ablation points.

For cryoablation cases, the procedure is unchanged with the exception of using a very stiff wire to exchange the transseptal sheath for the cryo sheath. Then, visualization of the Achieve catheter (Medtronic) and ICE are essential to guide proper placement of the cryoballoon.

Lastly, persistent atrial fibrillation frequently accompanied by complex LA flutters with redo and “three-do” cases all may be performed safely without the use of fluoroscopy (Figure 5, Video 2).

Summary

Whether SANS FLUORO, zero fluoro, no fluoro, or lead free, non-fluoroscopic ablations will indubitably continue to increase in popularity and availability. These techniques have been shown to be equally safe and effective, and will make the EP lab a less hazardous place for both patients and staff. As an early career EP, I have embraced the fluoroless approach and taught this technique to others. I look forward to the day when x-rays (and lead aprons) are an archaic relic of the distant past.

At our institution, we offer training to EPs and clinical staff on zero radiation ablation techniques. Please visit www.sansfluoro.com or @Sansfluorodoc for more information, cases, and weekly blogs. Special thanks to Bryan Heart Institute and EP Lab, as well as SANS FLUORO Association, staff, and members.

Disclosure: Dr. Percell reports that he is on speaker bureaus for Abbott, Medtronic, Biosense Webster, Janssen, Pfizer, and Boehringer Ingelheim, outside the submitted work.

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