In recent years, there has been an emerging interest in reducing radiation exposure, including near-zero and fluoroscopy-free EP procedures, as 3D mapping systems have become widely available. Numerous operators have reported successful ablations without any use of fluoroscopy, even in very complex cases.1,2 The biological effects of exposure to ionizing radiation are not only detrimental to patients and lab staff, but regular use of lead aprons by staff can also cause severe orthopedic degenerative diseases.3,4 Nevertheless, fluoroscopic-guided ablation is still standard in most EP labs, although the necessary equipment for fluoroscopy-free procedures, or at least minimal fluoroscopy use, is available. In this article, we describe our first experience with fluoroscopy-free ablation in Oldenburg.
The EP program in Oldenburg was developed in the early 2000s. Currently, approximately 350 ablation procedures a year are performed, including complex left atrial and ventricular procedures. The EP lab is equipped with a biplane fluoroscopy unit (AlluraClarity, Philips), digital signal processing (AXIOM Sensis EP System, Siemens), a standard EP stimulator (Qubic Stim, BIOTRONIK), an ablation generator (SMARTABLATE System, Biosense Webster, Inc., a Johnson & Johnson company), and a fully integrated 3D mapping system (CARTO 3 V6, Biosense Webster, Inc.). Apart from conventional and 3D mapping cases, cryoballoon ablation for atrial fibrillation is also routinely performed. The EP team currently consists of 1 director, 2 attending physicians, and 2 residents in training.
The patient is a 26-year-old male with a history of recurrent palpitations accompanied by dizziness and shortness of breath. Recently, a regular supraventricular tachycardia (SVT) with a short RP interval had been documented and terminated by bolus injection of 12 mg adenosine (Figure 1). The patient had no prior medical history and requested nonpharmacologic permanent treatment of his highly symptomatic tachycardia. He was referred to our center for elective invasive EP study and ablation.
The patient was brought to our EP lab and received a light conscious intravenous sedation using midazolam and fentanyl. Two short guiding sheaths were placed in the right femoral vein under additional local anesthesia with lidocaine and ropivacaine. The CARTO 3 mapping system (Biosense Webster, Inc.) was employed, and a 4 mm tip ablation catheter (NAVISTAR D curve, Biosense Webster, Inc.) was then carefully advanced through one of the guiding sheaths until atrial electrograms could be recorded. A 3D geometry of the right atrium without fluoroscopy was then acquired, the His region was mapped in detail, every site with a distinct His or bundle branch potential was marked in the 3D map (Figure 2), and baseline AV nodal measurements were recorded. Afterwards, the ablation catheter could easily be maneuvered into the coronary sinus (CS). Once proximal CS anatomy was complete, a second steerable decapolar diagnostic catheter (WEBSTER CS Bi-Directional D-F, Biosense Webster, Inc.) was advanced into the RA and successfully placed into the CS under guidance of the mapping system alone. For stimulation purposes, the ablation catheter was then placed in a stable right ventricular position.
Programmed atrial stimulation showed dual AV node conduction properties. After infusion of orciprenaline, the clinical tachycardia could be induced reproducibly by programmed atrial stimulation with 2 extrastimuli (Figure 3). The tachycardia showed AV synchronous activation (VA interval at CS ostium <20 ms), and ventricular overdrive pacing and His refractory premature beats consistently terminated the tachycardia. Due to a reproducible long AH jump before induction of the tachycardia, we considered the tachycardia to be typical slow-fast AV nodal reentrant tachycardia (AVNRT) and decided to perform slow pathway modulation.
The slow pathway region was mapped carefully with the ablation catheter. Typical signals with an A/V ratio of 1:5 could be recorded anterior to the CS ostium, inferior to the His region, and were marked. Radiofrequency (RF) was delivered at 50 W with a minimum distance of 17 mm to the closest mapped His potential under constant surveillance of AV conduction by a second operator. Numerous junctional beats were induced by RF delivery (Figure 4).
After a total of 4:03 minutes of RF ablation, the tachycardia was no longer inducible. There was no more evidence of slow pathway conduction, the AV and HV interval remained unchanged with physiologic antegrade AV conduction. The tachycardia also remained non-inducible after repeated administration of orciprenaline. The total procedure time (“skin-to-skin”) was 93 minutes, and the final lesion set can be seen in Figure 5 and Video 1 (scroll to end of article to view video). The sheaths were removed and the patient was discharged the following day.
The operators of this case were familiar with the use of 3D mapping; however, they did not use it in the setting of AVNRT and had never placed EP catheters without additional fluoroscopic guidance. Yet, there were no relevant difficulties during the case and it was completed in a reasonable time. The mean procedure time for AVNRT ablation at our lab over the last 2 years before this case was 65 minutes. From an economic standpoint, fluoroscopy-free ablation leads to higher costs — mostly attributable to the more expensive catheters — when compared to a standard approach. However, the benefits of not using ionizing radiation should outweigh these aspects by far. Moreover, physicians in Germany are required by law to use a radiation-free diagnostic or therapeutic measure whenever possible without disadvantages for the patient and staff. Thus, we would like to encourage every EP physician who has a 3D mapping system available and routinely uses fluoroscopy for AVNRT, AVRT, and typical flutter procedures to reduce radiation exposure to a minimum or zero fluoroscopy if possible. Precise knowledge of cardiac anatomy with experience from many previous fluoroscopy-guided procedures is crucial for catheter manipulation without visualization by fluoroscopy and creation of 3D structures.
In this article, we describe the first ablation without fluoroscopy at our center, which was easily performed by an operator without prior experience of fluoroscopy-free ablation but with extensive experience in standard invasive EP procedures. The use of fluoroscopy-free ablation techniques should be encouraged, as they imply great benefits to both patients and lab staff. They are also feasible in the vast majority of EP labs, as long as operators are experienced in the use of 3D mapping systems.
Disclosures: The authors have no conflicts of interest to report regarding the content herein.
- Sommer P, Bertagnolli L, Kircher S, et al. Safety profile of near-zero fluoroscopy atrial fibrillation ablation with non-fluoroscopic catheter visualization: experience from 1000 consecutive procedures. Europace. 2018;20:1952-1958.
- Rogers A, Brodt C. Minimizing radiation in the modern electrophysiology laboratory. J Innov Card Rhythm Manag. 2018;9:3265-3270.
- Fadl YY, Ellenbogen KA, Grubb RL, Khoo-Summers L, Lindsay BD. A review of spinal injuries in the invasive cardiologist: part 1. Biomechanics and pain generation. Pacing Clin Electrophysiol. 2007;30:1012-1019.
- Russo GL, Picano E. The effects of radiation exposure on interventional cardiologists. Eur Heart J. 2012;33:423-424.