ADVERTISEMENT
Zero Fluoroscopy Ablation of Atrial and Ventricular Arrhythmias in a Single Procedure
© 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(8):21-23.
Since our last article published in EP Lab Digest in 2020,1 which demonstrated our experience with zero fluoroscopy ablation for atrial fibrillation,2 catheter ablation of cardiac arrhythmias without the use of fluoroscopy has been established as a safe and effective technique, with numerous advantages over the conventional approach, without compromising safety and procedure time. In fact, it has become the main technique for all cardiac ablations in our service (with the possible exception of simple atrioventricular node ablation). However, in complex procedures, with multiples sources of arrhythmias, it may be challenging for less experienced operators to access different chambers with use of intracardiac echocardiography (ICE) and 3-dimensional (3D) mapping systems only.
Case Presentation
A 68-year-old man presented with a history of palpitations and shortness of breath with typical atrial flutter (AFL) and frequent premature ventricular complexes (PVCs), with right bundle branch block (RBBB) morphology and inferior axis, suggesting a left ventricular outflow tract (LVOT) origin (Figure 1). The nature of his symptoms, associated with the electrocardiographic documentation, made clear that both arrhythmias should be mapped and ablated in the same procedure.
The procedure was performed under general anesthesia, and the patient was monitored using 12-lead electrocardiogram and electroanatomic mapping (EAM) cutaneous patches (Carto 3, Biosense Webster, Inc, a Johnson & Johnson company). Under ultrasound guidance, right femoral vein access (including left femoral vein and right femoral artery access) was obtained.
From the left femoral vein, an ICE catheter (SoundStar 10 French [F], Biosense Webster) was advanced through the left iliac vein while keeping an “echo-free space” close to the near-field of the ultrasound image (representing absence of tissue contact at the tip of the ICE catheter). This technique allows the operator to clearly discriminate between a free-advancement of the tip of the ICE catheter through intravascular space when echo-free space is visible, and a palpable resistance to advancement when this image is not obtained.3 The ICE catheter was advanced to the right atrium (RA) until a “home view” image was obtained (Video 1). The catheter was flexed anteriorly through the tricuspid valve to the right ventricular inflow tract (RVIT) to obtain a clear image of the pericardial space in different echo planes to set the baseline to compare later in the procedure. In the RA, a posterior tilt of the ICE catheter allowed for visualization of the superior vena cava (SVC) to proceed with mapping.
Video 1
Video 1. ICE visualization of home view during AFL.
A long guide wire was then inserted through the right femoral vein, and smooth progression to the SVC was guided by ICE imaging. A long transseptal sheath was advanced over the wire and placed in the SVC. A multipolar catheter was then inserted in the long Vizigo sheath (Biosense Webster), and both geometry and activation mapping of the RA and coronary sinus (CS) were created during AFL, allowing for positioning of a decapolar catheter in the CS and a quadripolar catheter in the RV.
CS atrial activation during AFL was proximal to distal, with a cycle length of 224 milliseconds. The time from the peak of F-wave in lead V1 to the mid CS activation (dipole CS 5-6) was 128 milliseconds (Figure 2), representing approximately 57% of the cycle length, suggesting a peritricuspid circuit.3 The 3D EAM confirmed a counterclockwise-rotating macroreentry (Video 2), and entrainment from the cavotricuspid isthmus (CTI) confirmed a CTI-dependent AFL. CTI ablation guided by ICE and contact force was performed (Video 3), and interrupted the AFL converting to junctional rhythm (Figure 3). Bidirectional block was confirmed by double potentials along the line during proximal CS pacing (Figure 4) in combination with differential pacing of the lateral wall with the ablation catheter.
Video 2
Video 2. Activation mapping of counterclockwise AFL.
Video 3
Video 3. Irrigated catheter at the CTI during RF ablation. The catheter can be seen by EAM and in ICE.
After termination of typical AFL, the PVCs remained. An irrigated catheter was advanced via a retrograde approach through the right femoral artery using a standard short 8F sheath (ACT of 300 seconds). To safely achieve this, the ICE catheter was withdrawn to the inferior vena cava (IVC) and directed to visualize the infrarenal aorta and iliac arteries. It was possible to visualize the catheter progression (Video 4) in the whole arterial bed (with exception to the portion located beneath the liver). The ICE catheter was then positioned in the SVC to visualize the aortic arch. The ablation catheter was bended to assume an atraumatic loop-shape and progressed to the ascending aorta and LV under ICE and EAM visualization (Video 5).
Video 4
Video 4. ICE visualization of ablation catheter retrogradely advanced through the right iliac artery and aorta.
Video 5
Video 5. ICE and EAM visualization of ablation catheter retrogradely advanced through ascending aorta. The catheter was bended to cross the aortic valve in an atraumatic fashion.
The ICE catheter was then positioned in the RV, and after progressive clockwise torque, a transverse aortic root image was obtained and the shape of the aortic sinus of Valsalva (left, right, and noncoronary) was drawn using CartoSound (Biosense Webster) (Video 6). It was easy to individualize the mapping of the sinus of Valsalva, which served as a clear marker to differentiate subvalvular and supravalvular regions during LV mapping. Other important structures such as the mitral annulus and papillary muscles may be drawn using ICE to create a comprehensive anatomical map.4
Video 6
Video 6. ICE image showing a cross section of the aortic valve and aortic sinus of Valsalva. EAM performed with CartoSound shows the anatomic representation of the cusps.
During activation mapping of the LVOT, a potential preceding the PVC-QRS (by 23 milliseconds) was detected at the junction of the left and right coronary cusp (Figure 5). Radiofrequency (RF) ablation in that area eliminated the PVCs (Figure 6); further RF applications in the LV summit area were performed to consolidate the results.
After 20 minutes of observation, no PVCs were present and the CTI bidirectional block was again confirmed. Systemic heparinization was reverted with protamine, venous access hemostasis was granted using inguinal Prolene #0 figure-of-8 sutures (Ethicon, a Johnson & Johnson company), and arterial access was closed with Perclose ProGlide (Abbott) and compressive dressing. The patient was discharged the next morning using oral anticoagulation and without the use of antiarrhythmic drugs.
The entire procedure was performed in 90 minutes, without the use of fluoroscopy. Every catheter position in both the right and left circulation and aorta was safely monitored using ICE. Especially during LVOT mapping, ICE manipulation was performed by an experienced assistant electrophysiologist, helping the main operator stay focused on ablation catheter manipulation.
Discussion
A typical CTI-dependent AFL ablation is usually one of the first procedures done by electrophysiology (EP) fellows in training, but it can sometimes be challenging to perform. For example, the presence of a prominent Eustachian valve can prevent an ablation catheter from reaching the CTI segment close to the IVC using the standard approach. Often, bending the catheter to a “candy cane” shape and monitoring contact with an ICE catheter can be beneficial and allow for improved CTI block. In other instances, the presence of pouches in the CTI tissue may increase the risk of poor catheter tip irrigation and eventual steam pop formation. ICE visualization and contact force control are the recommended tools to overcome these anatomical variations and avoid complications, allowing for power titration when ablating these pouches.
ICE visualization during LVOT mapping and ablation requires some tricks and tips for best practice. Perhaps the best approach in these cases is to set a structure such as the aortic root as an anatomical reference for visualization. Using the aortic root view (also called a para-Hisian view, from the RVOT – Video 6) as a prompt, a counterclockwise torque will likely show the subvalvular structures (LV summit, LVOT). In contrast, a clockwise torque from the aortic root view will allow visualization of the supravalvular structures (ascending aorta, aortic sinus of Valsalva, and left main coronary artery [LMCA] ostia). In addition, because the LMCA and right coronary artery originate from the middle of the cusps, the junction of the cusps may be a safer place to map and even to start RF if the signals are suitable for ablation. This precise information is only possible with the aid of ICE, and it potentially avoids the need for coronary angiography.
Because of the anatomical characteristics of the LV summit and LVOT, RF ablation of PVCs originating in this area may be challenging, sometimes requiring longer RF applications to reach deep myocardial sources.5 Other groups advocate RF applications from different structures (such as the right ventricular outflow tract [RVOT] and pulmonary artery).
As in this particular case and in every outflow tract PVC case, ICE played an important role during RF application due to the ability to continuously evaluate the myocardial reaction to RF delivery. When a hyperechogenic blur slowly appears in the ventricular myocardium underneath the ablation catheter (Video 7), there is a strong correlation with the drop in impedance, representing an effective lesion. However, the appearance of a sudden hyperechogenic tissue blur sometimes precedes a rise in impedance and steam pop. When this happens, immediately stopping RF and returning to a lower power has demonstrated to be a potentially complication-saving approach. If tissue echogenicity is observed and suppression of PVCs is confirmed, a tag of the myocardial tissue can be drawn using CartoSound and that myocardial substrate can be precisely reached from the opposing RVOT or pulmonary artery to perform additional ablations, if necessary.
Video 7
Video 7. ICE image shows ablation tissue effect in the LVOT.
Conclusion
This case highlights the importance of the advanced use of ICE and EAM without fluoroscopy to treat different arrhythmic sources from both the RA and LVOT, close to the aortic sinus of Valsalva, with a high degree of precision and safety. We selected this case because it shows that the combination of standard EP knowledge, interpretation of electrograms to best define macroreentrant atrial circuits, and the advanced image and mapping technologies available in our field provide great results while minimizing recurrences with one single procedure.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. They report no conflicts of interest regarding the content herein. Outside the work, Dr Saad reports payment from Abbott and Biosense Webster for lectures and presentations.
References
1. Saad EB. Catheter ablation for atrial fibrillation without x-rays: the zero fluoro technique. EP Lab Digest. 2020;20(1):1,12-17.
2. Saad EB, Slater C, Inácio LAO, Santos GV Dos, Dias LC, Camanho LEM. Catheter ablation for treatment of atrial fibrillation and supraventricular arrhythmias without fluoroscopy use: acute efficacy and safety. Arq Bras Cardiol. 2020;114(6):1015-1026. doi:10.36660/ABC.20200096
3. Pascale P, Shah AJ, Roten L, et al. Pattern and timing of the coronary sinus activation to guide rapid diagnosis of atrial tachycardia after atrial fibrillation ablation. Circ Arrhythm Electrophysiol. 2013;6(3):481-490. doi:10.1161/CIRCEP.113.000182
4. Romero J, Diaz JC, Gamero M, et al. Fluoroless catheter ablation of left ventricular summit arrhythmias: a step-by-step approach. Card Electrophysiol Clin. 2023;15(1):75-83. doi:10.1016/j.ccep.2022.10.002
5. Garg L, Daubert T, Lin A, et al. Utility of prolonged duration endocardial ablation for ventricular arrhythmias originating from the left ventricular summit. JACC Clin Electrophysiol. 2022;8(4):465-476. doi:10.1016/J.JACEP.2021.12.010
