Dielectric imaging for electrophysiology procedures: The technology, current state, and future potential

One-year outcomes of wide antral cryoballoon ablation guided by high-density mapping vs. conventional cryoballoon ablation for atrial fibrillation: a propensity score-matched study

Background

Pulmonary vein isolation with wide antral ablation leads to better clinical outcomes for the treatment of atrial fibrillation, but the isolation lesion is invisible in conventional cryoballoon ablation. In this study, we aim to investigate the efficacy of the wide pulmonary vein isolation technique that includes the intervenous carina region, guided by high-density mapping, compared with pulmonary vein isolation alone without the mapping system.

Methods

We conducted a propensity score-matched comparison of 74 patients who underwent a wide cryoballoon ablation guided by high-density mapping (mapping group) and 74 controls who underwent conventional cryoballoon ablation in the same period (no-mapping group). The primary outcome was a clinical recurrence of documented atrial arrhythmias for >30 s during the 1-year follow-up.

Results

Of 74 patients in the mapping group, residual local potential in the pulmonary vein antrum was found in 30 (40.5%) patients, and additional cryothermal applications were performed to achieve a wide pulmonary vein isolation. Compared with the no-mapping group, the use of the mapping system in the mapping group was associated with a longer fluoroscopic time (26.97 ± 8.07 min vs. 23.76 ± 8.36 min, P = 0.023) and greater fluoroscopic exposure [339 (IQR181-586) mGy vs. 224 (IQR133-409) mGy, P = 0.012]. However, no significant differences between the two groups were found in terms of procedural duration and left atrial dwell time (104.10 ± 18.76 min vs. 102.45 ± 21.01 min, P = 0.619; 83.52 ± 17.01 min vs. 79.59 ± 17.96 min, P = 0.177). The rate of 12-month freedom from clinical atrial arrhythmia recurrence was 85.1% in the mapping group and 70.3% in the no-mapping group (log-rank P = 0.029).

Conclusion

Voltage and pulmonary vein potential mapping after cryoballoon pulmonary vein isolation can identify residual potential in the pulmonary vein antrum, and additional cryoablation guided by mapping leads to improved freedom from atrial arrhythmias compared with conventional pulmonary vein isolation without the mapping system.

Clinical Trial Registration Number

ChiCTR2200064383.

Feasibility study of cryoballoon ablation for atrial fibrillation with KODEX-EPD: a single center experience

To evaluate the feasibility of cryoballoon (CB) ablation of atrial fibrillation (AF) under the guidance of a new three-dimensional (3D) mapping system KODEX-EPD. 40 patients scheduled for CB ablation of AF in the first affiliated Hospital of Xinjiang Medical University from August 2021 to July 2022 were randomly divided into two groups: KODEX-EPD 3D mapping system guidance group (KODEX group, n = 20) and conventional two-dimensional perspective group (standard group, n = 20). The ablation time, operation time, fluoroscopy time, fluoroscopy dose, contrast agent dosage and follow-up data were compared between the two groups. Besides, the feasibility and accuracy of the dielectric sensing system in evaluating pulmonary vein (PV) occlusion in patients with AF during CB ablation were verified. All pulmonary veins were being isolated. The ablation time (36.40 ± 6.72 min vs 35.15 ± 6.29 min, P > 0.05) and the operation time (64.20 ± 11.82 min vs 66.00 ± 13.18 min, P > 0.05) were not statistically different in the two groups. The standard group has longer fluoroscopy time, dose and contrast medium dosage. There were significant differences in fluoroscopy time (532.30 ± 72.83 s vs 676.25 ± 269.33 s, P < 0.05), fluoroscopy dose (110.00 ± 28.64 mGy vs 144.68 ± 66.66 mGy, P < 0.05), and contrast medium dosage (71.90 ± 5.97 ml vs 76.05 ± 5.93 ml, P < 0.05) between the two groups. The learning curves of the first 5 patients and the last 15 patients in the KODEX group were compared. There was no statistical difference in the ablation time (36.80 ± 8.56 min vs 36.27 ± 6.34 min, P > 0.05) or the operation time (69.00 ± 5.00 min vs 62.60 ± 13.10 min, P > 0.05); however, compared to the first 5 patients, fluoroscopy time (587.40 ± 38.34 s vs 513.93 ± 73.02 s, P < 0.05), fluoroscopy dose (147.85 ± 35.19 mGy vs 97.39 ± 8.80 mGy, P < 0.05) and contrast medium dosage (79.60 ± 1.14 ml vs 69.33 ± 4.45 ml, P < 0.05) were significantly decreased. Using pulmonary venography as the gold standard, the sensitivity, specificity of the completely occlusion in KODEX group was 93.6% (95% CI 85-97.6%) and 69.6% (95% CI 54-81.8%); and the sensitivity, specificity of the small leak in KODEX group was 93.1% (95% CI 82.4-97.8%) and 82.0% (95% CI 65.9-91.9%). During an average follow-up of (9.90 ± 1.06) months, there was no statistical difference in arrhythmia recurrence and antiarrhythmic drugs taking after CB ablation between the two groups (P > 0.05). Using the KODEX-EPD system, the CB ablation procedure can correctly evaluate the PV occlusion, and significantly reduce fluoroscopy exposure and contrast medium without significantly increasing the operation time.

Dielectric response as a novel marker for ablation lesion quality: Relation to conventional ablation parameters

Background

The tissue response viewer (TRV) is a novel marker for ablation lesion quality that aims to classify lesions into transmural or nontransmural lesions (high or low dielectric response, HDR or LDR) using dielectric-based tissue assessment. The objective of this study was to gain insight in the TRV by relating its outcomes to conventional ablation parameters.

Methods

Patients that had repeat ablation for atrial fibrillation with a dielectric imaging-based mapping system were enrolled. All ablation data were downloaded from the mapping system and analyzed to explore associations between TRV outcomes and other ablation parameters.

Results

The cohort included 24 patients, in which 58 pulmonary veins and 8 superior vena cavas were targeted. A total of 388 energy applications were applied, resulting in 639 ablation points. The system classified 36% of ablation points as HDR and 44% as LDR. The system did not provide a dielectric response in 20%. The system's ability to provide a dielectric response was related to longer ablation duration and absence of dragging ablation. HDR (versus LDR) was multivariably associated with longer energy applications, higher mean ablation power, and lower wall thickness. Greater impedance drop was univariably associated with HDR.

Conclusion

Outcomes of the TRV are associated with conventional ablation parameters (e.g., duration and power) but also local wall thickness. Catheter stability seems important for successful lesion assessment with the TRV. Further reduction of missing outcomes and validation of the tool are warranted before widespread use.

Low fluoroscopy permanent His bundle pacing using a new electroanatomic mapping system (KODEX EPD). A multicenter experience

Background

His bundle pacing (HBP) may be a challenging procedure, often involving a long fluoroscopic time (FT) and a long procedural time (PT). We sought to evaluate whether the use of a new nonfluroscopic mapping (NFM) system, the KODEX-EPD, is able to reduce FT and PT when mapping is performed by the pacing catheter rather than an electrophysiological mapping catheter.

Methods and Results

We included 46 consecutive patients (77 ± 8 years; 63% male) who underwent HBP; in 22 a NFM-guided procedure with the KODEX-EPD system was performed (group 1), whereas in 24 a conventional fluoroscopy-guided approach was used (group 2). Pacing indications were sick sinus syndrome in 13, atrioventricular block in 21, and cardiac resynchronization therapy in 12 cases. Both a lumen-less fixed helix lead and a stylet-driven extendable helix lead were used, respectively, in 24% and 76% of patients. HBP was successful in 22 patients (100%) in group 1 and 23 patients (96%) in group 2. The FT was significantly reduced in group 1 (183 ± 117 s vs 464.1 ± 352 s in group 2, p = .012). There were no significant differences between groups in PT and other procedural outcomes.

Conclusions

The KODEX-EPD system may be safely used in HBP procedures. It is effective in reducing ionizing radiation exposure, as evidenced by the significant drop in FT, without increasing PT.

Atrial conduction velocity mapping: clinical tools, algorithms and approaches for understanding the arrhythmogenic substrate

Characterizing patient-specific atrial conduction properties is important for understanding arrhythmia drivers, for predicting potential arrhythmia pathways, and for personalising treatment approaches. One metric that characterizes the health of the myocardial substrate is atrial conduction velocity, which describes the speed and direction of propagation of the electrical wavefront through the myocardium. Atrial conduction velocity mapping algorithms are under continuous development in research laboratories and in industry. In this review article, we give a broad overview of different categories of currently published methods for calculating CV, and give insight into their different advantages and disadvantages overall. We classify techniques into local, global, and inverse methods, and discuss these techniques with respect to their faithfulness to the biophysics, incorporation of uncertainty quantification, and their ability to take account of the atrial manifold.

A Novel Wide-band Dielectric Imaging System for Electro-anatomic Mapping and Monitoring in Radiofrequency Ablation and Cryoablation

Background and Objectives

A novel wide-band dielectric mapping system, named as KODEX-EPD (EPD Solutions, Philips, Best, the Netherlands), was effectively used in the EA mapping for atrial fibrillation (AF) ablation. To date, only a few studies have concentrated on the application of the KODEX-EPD system for ablating supraventricular tachycardia or ventricular premature beats (VPBs) in human models. This study aims to assess the applicability and efficiency of a novel three-dimensional electro-anatomic (EA) mapping system to improve the success rate of ablation.

Methods

This study included 11 consecutive patients who underwent ablation after EA mapping with the KODEX-EPD system.

Results

All surgeries were successfully performed using the KODEX-EPD system, including 6 cases who underwent ablation of paroxysmal supraventricular tachycardia (PSVT), 2 cases who received ablation of VPBs from right ventricular outflow tract (RVOT), and 3 cases who underwent cryoablation of AF. For ablation of PSVT or VPBs, the operation time was 31.4 (range, 24.0-38.0) min, in which a median operation time of 2.9 min was used to create anatomic images, and the median fluoroscopic dose was 7.4 mGy. For ablation of AF, the operation time was 56.0 (range, 49.0-62.0) min, in which a median of 4.3 (range, 3.4-5.2) min was used for constructing left atrium map, and the median fluoroscopic dose was 15.0 mGy. The operation time and the fluoroscopic dose were greatly shortened for all surgeries.

Conclusion

The KODEX-EPD system is an effective and safe tool to guide the EA mapping, leading to improvement in the success rate of ablation. It can promote the ablation process with the reduced fluoroscopic dose, and it is also a promising tool for complex surgeries.

Cryoballoon ablation guided by a novel wide-band dielectric imaging system

Background and aim

To investigate the feasibility, acute efficacy, periprocedural safety, and procedural parameters of CB-based PVI guided by KODEX-EPD using different occlusion tool software versions.

Methods and results

A total of 173 patients (60/173 (35%) paroxysmal AF, 64 ± 12 years, 66/173 (38%) female), underwent CB-based PVI guided by KODEX-EPD between August 2019 and October 2021. Acute PVI was achieved in all the patients. Total fluoroscopy time and dye volume were 13.9 [10.6–19.4] min and 47.5 [20–70] ml. Periprocedural complications occurred in 3 (2%) of the 173 patients. As part of the continued development program, different software versions were used, including 1.4.6 on 38 (22%), 1.4.6a on 33 (19%), 1.4.7 on 41 (24%), and 1.4.8 on 61 (35%) of the patients. Outcomes were compared between software versions by a univariate analysis. Sensitivity analyses were performed to account for confounders. Median fluoroscopy time was decreased by 6.4 min (37.3%), and the median volume of dye was decreased by 32.5 ml (52%) from versions 1.4.6 to 1.4.8. Software version was a significant predictor of fluoroscopy time and dye volume, while reductions in procedure duration and dose area product were observed but mainly explained via confounders.

Conclusion

CB-based PVI guided by KODEX-EPD is feasible and safe. Progressive software improvements appear to be associated with lower fluoroscopy duration and dye use. Further studies are needed to evaluate the advantage of KODEX-EPD-guided compared to conventional CB-PVI.

Catheter Ablation in Complex Atrial Arrhythmias: Pilot Study Evaluating a 3D Wide-Band Dielectric Imaging System

Background

Cryoballoon ablation (CBA) for pulmonary vein isolation (PVI) is a standard in atrial fibrillation (AF) ablation but might not be enough in complex atrial arrhythmias (AA). An open three-dimensional wide-band dielectric imaging system (3D-WBDIS) has been introduced to guide CBA.

Material and Methods

Pilot study evaluating feasibility and safety of 3D-WBDIS in combination with CBA and optional radiofrequency ablation (RFA) in patients with complex AA defined as (1) history of persistent AF, (2) additional atrial tachycardia/flutter, or (3) previous left atrial ablation.

Results

Prospectively, seventeen patients, 68.9 ± 12.2 years of age, with complex AA were enrolled. In 70 pulmonary veins (PV), balloon positioning maneuvers (n = 129) were guided additionally by the occlusion tool (1.84/PV). Compared to angiography, its sensitivity and specificity was 94.5, and 85%, respectively. CBA-PVI was achieved in 100% of PVs including variants. In 68 maps, the median number of mapping points was 251.0 (interquartile range (IQR) 298.0) with a median map volume of 52.8 (IQR 83.9) mL. Following CBA, six additional arrhythmias (two right and two left atrial flutter, one left atrial appendage tachycardia, and one atrioventricular nodal reentry tachycardia) were identified and successfully ablated by means of RFA in five patients (29.4%). Left atrial and fluoroscopy times were 88 (IQR 40) and 20 (IQR 10) minutes, respectively. Dose area product was 1,100 (IQR 1252) cGyxcm². Freedom from AA after 6 months follow-up time and 90 days blanking period was documented in 10/17 (59%) patients, and 8/17 (47%) without a blanking period. No major complication was observed.

Conclusion

The combined use of CBA with optional RFA guided by a novel 3D-WBDIS is feasible and safe in patients suffering from complex AA. The occlusion tool shows high sensitivity and specificity for assessment of the balloon occlusion. Additional arrhythmias were successfully mapped and ablated. Short-term outcome is promising, and subsequent prospective, larger outcome studies are necessary to confirm our observations.

Applications of multimodality imaging for left atrial catheter ablation

Atrial arrhythmias, including atrial fibrillation and atrial flutter, may be treated through catheter ablation. The process of atrial arrhythmia catheter ablation, which includes patient selection, pre-procedural planning, intra-procedural guidance, and post-procedural assessment, is typically characterized by the use of several imaging modalities to sequentially inform key clinical decisions. Increasingly, advanced imaging modalities are processed via specialized image analysis techniques and combined with intra-procedural electrical measurements to inform treatment approaches. Here, we review the use of multimodality imaging for left atrial ablation procedures. The article first outlines how imaging modalities are routinely used in the peri-ablation period. We then describe how advanced imaging techniques may inform patient selection for ablation and ablation targets themselves. Ongoing research directions for improving catheter ablation outcomes by using imaging combined with advanced analyses for personalization of ablation targets are discussed, together with approaches for their integration in the standard clinical environment. Finally, we describe future research areas with the potential to improve catheter ablation outcomes.

Novel Wide-Band Dielectric Imaging System Guided Lead Deployment for His Bundle Pacing: A Feasibility Study

Introduction: His bundle pacing (HBP) is the most widely used physiological pacing modality, but difficulties in locating the His bundle lead to high fluoroscopic exposure. An electroanatomical mapping (EAM) system can be an efficient tool to achieve HBP implantation with near-zero fluoroscopic visualization.

Methods: In the study, 20 patients who had indications for pacemaker implantation were prospectively enrolled and underwent HBP implantation either with the conventional fluoroscopy approach (the standard group) or guided by a novel KODEX-EPD mapping system (the EAM-guided group). The success rate, procedural details, pacing parameters, and procedure-related complications were compared between the two groups.

Results: In the study, 20 consecutive patients were randomized with 10 patients in each group. HBP was successfully achieved in nine patients in the standard group and nine patients in the EAM-guided group. The procedural time was similar between the EAM-guided group vs. the standard group (85.40 ± 22.34 vs. 86.50 ± 15.05 min, p = 0.90). In comparison with the standard group, the EAM-guided group had a significant shorter total fluoroscopic time (FT) (1.45 ± 0.58 vs. 12.36 ± 5.46 min, p < 0.01) and His lead fluoroscopic time (HL-FT) (0.84 ± 0.56 vs. 9.27 ± 5.44 min, p < 0.01), while lower total fluoroscopic dose (3.13 ± 1.24 vs. 25.38 ± 11.15 mGy, p < 0.01) and His lead fluoroscopic dose (1.85 ± 1.17 vs. 19.06 ± 11.03 mGy, p < 0.01). No significant differences were observed in paced QRS duration and pacing parameters between the two groups. During a 3-month follow-up, one patient had a capture threshold increased >1 V/1.0 ms in the standard group, while no other complications were recorded in either group.

Conclusion: The KODEX-EPD system could facilitate HBP implantation with significantly reduced FT and dose without compromising the procedural time.