Fluoroless cryo-ablation of para-Hisian accessory pathway 127 Klinični primer Zdrav Vestn | marec – april 2017 | l etnik 86 Department of Cardiovascular Surgery, Division of Surgery, University Medical Centre Ljubljana Korespondenca/ Correspondence: matevž Jan, e: janmatevz@hotmail. com Ključne besede: elektrofiziologija; tridimenzijsko elektroanatomsko mapiranje; znotrajsrčni elektrogram; midseptalna akcesorna pot; kriomapiranje Key words: electrophysiology; three- dimensional electro- anatomic mapping system; intracardiac electrogram; mid-septal accessory pathway; cryo- mapping Citirajte kot/Cite as: Zdrav Vestn. 2017; 86: 127–30. prispelo: 16. 6. 2015 Sprejeto: 2. 2. 2017 Klinični primer Srce in ožilje 1381 Fluoroless cryo-ablation of para-Hisian accessory pathway Krioablacija parahisarne akcesorne poti brez uporabe rentgenske diaskopije Tine prolič Kalinšek, Jure Jug, matevž Jan, Borut Geršak Abstract W e present a case of para-Hisian accessory pathway ablation in a patient with W olff-Parkinson-Whi- te syndrome, which was performed with cryoablation to reduce the possibility of collateral damage to the conduction system of the heart. We also used fluoroless approach to exclude possible harm from radiation exposure, using only intracardial electrograms and three-dimensional (3D) electro- -anatomic mapping system to navigate the catheters in the heart. Izvleček Predstavljamo primer ablacije parahisarne akcesorne poti, ki smo jo opravili pri bolniku s sindro- mom W olff-Parkinson-White. Opravili smo krioablacijo, da bi čim bolj zmanjšali možnost poškodbe prevodnega sistema srca med ablacijo. Za usmerjanje katetrov na ustrezna mesta v srcu smo upora- bili le znotrajsrčne elektrokardiograme in sistem za tridimenzionalno (3D) mapiranje. Rentgenske diaskopije nismo uporabili, s čimer smo izključili možnost škodljivih vplivov rentgenskega sevanja. Background Thirty-three years old male patient was diagnosed with the Wolff-Parkin- son-White (WPW) syndrome. A 12-lead electrocardiogram revealed the delta wave pattern consistent with the presen- ce of a mid-septal accessory pathway (Fi- gure 1A). He had monthly attacks of fast heart rate that lasted 2 to 3 minutes. He was otherwise healthy and had structu- rally normal heart. Due to the presumed accessory pathway location, close to the conduction system of the heart, we cho- se cryo-ablation as a treatment option. The cryo-ablation approach is based on the tissue cooling instead of heating as in the radiofrequency ablation. It enables the operator to first perform the cryo- -mapping (at minus 30°C, creating re- versible tissue damage) at different sites of interest to check for possible collateral damage. When the cryo-mapping results in a favorable response, it is followed by cryo-ablation (at minus 70°C, creating irreversible tissue damage). The proce- dure was performed completely without the use of fluoroscopy. Case presentation The patient was awake during the whole procedure. We performed a per- cutaneous femoral vein puncture and inserted a 10-polar electrophysiology catheter into the coronary sinus, a 4-po- 128 Zdrav Vestn | marec – april 2017 | l etnik 86 Srce in ožilJe Figure 1: (A) An ec G of a patient before the ablation showing a delta wave pattern consistent with the presence of a mid-septal accessory pathway. (B) partial 3D colour-coded activation map of the right atrium. White colour indicates the area of the earliest activation of the ventricle. T ricuspid annulus is marked with white dots. Brown dots depict the location of the earliest activation of ventricle in the septal region. cryo-ablation was performed where the red dots are. (c) endocardial electrocardiogram after the ablation. Arrows mark the far field signal of the His bundle on the distal pole of the cryo-ablation catheter at the location of a successful cryo-ablation. lar electrophysiology catheter into the high right atrium and an ablation cathe- ter into the right ventricle. Ventricular pacing demonstrated non-decremental atrio-ventricular and ventriculo-atri- al conduction indicating conduction over an accessory pathway. The ablation catheter and the EnSite/NavX™ (St. Jude Medical) 3D electro-anatomic mapping system were used for the reconstruction of a partial 3D model of the right atrium. Mapping near the area of the tricuspid annulus during sinus rhythm revealed the earliest activation of the ventricle in the septal region. After narrowing the fi- eld of interest, the cryo-mapping at the earliest ventricular activation was per- formed with the Freezor Xtra™ (Med- tronic) catheter (Figure 1B). Three cryo- -ablations at minus 70°C, each lasting 4 minutes, were performed at the site whe- re cryo-mapping at minus 30°C revealed block of conduction over the accessory pathway and normal conduction over the atrio-ventricular node. We detected a far field signal of the His bundle on the distal pole of the cryo-ablation catheter immediately after the first cryo-ablation (Figure 1C) indicating the presence of a true para-Hisian accessory pathway. We did not detect any ventricular pre-excita- tion (no delta wave) on the 12-lead ECG thirty minutes after the cryo-ablation. After a six-month follow-up, the patient was free of ventricular pre-excitation and symptoms of tachycardia. Fluoroless cryo-ablation of para-Hisian accessory pathway 129 Klinični primer Discussion Guidelines for the treatment of the WPW syndrome recommend the cathe- ter ablation as a first line treatment (1). This is also the treatment of choice for para-Hisian accessory pathways. In our case, a true para-Hisian nature of the septal accessory pathway was reve- aled after the initial cryo-ablation. There are some advantages of cryo-ablation of accessory pathways close to the conduc- tion system compared to radiofrequency ablation. Firstly, the possibility of cryo- -mapping, which enables the confirmati- on of successful and safe ablation target before definitive and irreversible cryo- -ablation. Secondly, improved stability of catheter tip because of its adherence to tissue during cryo-ablation, compared to radiofrequency ablation. Such stabili- ty provides more precise and smaller le- sions with a similar depth as lesions cre- ated by radiofrequency ablation. Thirdly, complications such as a prolonged PR interval as well as AV blocks during cryo-mapping are completely reversible and are not permanent (2,3), compared to radiofrequency ablation of antero- -septal accessory pathways, in which the risk of permanent AV block is reported to be up to 2.7 % (4). Although the acute procedural success rate of cryo-ablati- on is lower than that of radiofrequency ablation (69 % vs. 93 %), it is preferable to use cryo-ablation when the possi- bility of permanent AV block is more probable (5). In the case of para-Hisian accessory pathway ablation, cryo-ablati- on was demonstrated to be safe with no long-term complications (6,7). When the cryo-ablation procedure is successful, its long-term success rate is 91 %, which is comparable to radiofrequency ablati- on (5). The procedure was performed wi- thout the use of fluoroscopy and only with the aid of intracardiac electro- grams and the 3D electro-anatomic ma- pping system. The procedural duration of accessory pathway ablation with the aid of the 3D electro-anatomic mapping system seems to be less than when fluo- roscopy alone is used (177.06 ± 62.189 vs 242.45 ± 99.07 minutes)  (8). In procedu- res where fluoroscopy is used, the mean duration exposure time is 47 ± 33 minu- tes, which translates to 1.9 ± 3.2 mGy of radiation exposure. The lifetime risk for patients of developing fatal malignancy is 0.08 % and the risk for developing he- reditary effects is 20 per million cases  (9). The use of fluoroscopy is also linked to a higher incidence of brain (particularly on the left side of the brain associated with proximity of x-ray machine) and neck tumors among electrophysiolo- gists and other physicians performing interventional procedures  (10). Also, ablation of accessory pathways with the aid of the 3D electro-anatomic mapping system has higher success rate compa- red to ablation done with fluoroscopy alone (97 % vs. 91 %) with no significant difference in recurrence (5 % vs. 9 %) or complication rate (0.3 % vs. 0.4 %)  (11). Fluoroless ablation with the aid of the 3D electro-anatomic mapping system is thus a more attractive alternative for both, the patient and the physician. References 1. Blomström-Lundqvist C, Scheinman MM, Aliot EM, Alpert JS, Calkins H, Camm AJ, et al. ACC/ AHA/ESC guidelines for the management of pa- tients with supraventricular arrhythmias-executi- ve summary. 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