High-density Mapping System Research Articles

Catheter ablation of supraventricular tachycardia

Supraventricular tachycardias (SVT) are common, with atrioventricular nodal reentry tachycardias (AVNRT) being the most common paroxysmal supraventricular tachycardia. The pathophysiological understanding and the catheter ablation of SVTs have developed steadily in recent years. For example, dividing AVNRT into "typical" and "atypical" depending on the HA-, VA-interval and AH/HA ratio is recommended. Because of higher rates of recurrences after cryoablation, radiofrequency ablation has prevailed in AVNRT. The current ESC guidelines for SVTs recommend the ablation of accessory pathways in asymptomatic high-risk patients and it is now aClassI recommendation. There is no recommendation for the access in left-sided accessory pathways. However, atransseptal compared to transaortic approach seems more promising in acute success. The use of athree-dimensional (3D) mapping system leads to areduction of the fluoroscopy times and procedure duration. Ablation of focal atrial tachycardia remains challenging despite the use of 3D electroanatomical mapping systems. However, new technologies such as high-density (HD) multipoint mapping systems can be helpful. HD mapping systems also allow abetter understanding of left and right atrial macroreentry tachycardia after previous ablation or cardiac surgery and in primary nature. However, in all technological advances, a proficient understanding of the basic techniques in electrophysiology, such as entrainment mapping, is mandatory.

P3778Long-term outcome of non-pharmacologial treatment of atrial fibrillation in hypertrophic cardiomyopathy: a large single-centre experience

Abstract Introduction Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM) and is generally associated with a significant deterioration of clinical status. Non-pharmacological treatment such as surgical and catheter ablation has become an established therapy for symptomatic AF but in patients with HCM often having a chronically increased left atrial pressure and extensive atrial cardiomyopathy the long-term outcome is uncertain. Purpose The present study aimed to analyse the long-term outcome of AF ablation in HCM and the mechanism of recurrent atrial arrhythmias using high-density mapping systems. Methods A total of 65 patients (age 64.5±9.9 years, 42 (64.6%) male) with HCM undergoing AF ablation for symptomatic AF were included in our study. The ablation strategy for catheter ablation included pulmonary vein isolation in all patients and biatrial ablation of complex fractionated electrograms with additional ablation lines if appropriate. In patients with suspected atrial tachycardia (AT) high-density activation and substrate mapping were performed. A surgical ablation at the time of an operative myectomy for left ventricular outflow tract obstruction was performed in 8 (12.3%) patients. The outcome was analysed using clinical assessment, Holter ECG and continuous rhythm monitoring of cardiac implantable electric devices. Results Paroxysmal AF was present in 27 (41.6%), persistent AF in 37 (56.9%) and primary AT in 1 (1.5%) patients. The mean left atrial diameter was 54.1±12.5 ml. In 11 (16.9%) patients with AT high-density mapping was used to characterize the mechanism of the ongoing tachycardia. After 1.9±1.2 ablation procedures and a follow-up of 48.5±37.2 months, ablation success was demonstrated in 58.9% of patients. The success rate for paroxysmal and persistent AF was 70.0% and 55.8%, respectively (p=0.023). Of those patients with AT high-density mapping guided ablation was successful in 44.4% of patients. The LA diameter of patients with a successful ablation was smaller (52.2 vs. 58.1 mm; p=0.003). Conclusion Non-pharmacological treatment of AF in HCM is effective during long-term follow-up. Paroxysmal AF and a smaller LA diameter are favourable for successful ablation. In patients with complex AT the use of high-density mapping can guide ablation resulting in further ablation success in a reasonable number of patients.

High-density Mapping Guided Pulmonary Vein Isolation for Treatment of Atrial Fibrillation - Two-year clinical outcome of a single center experience

Pulmonary vein isolation (PVI) as interventional treatment for atrial fibrillation (AF) aims to eliminate arrhythmogenic triggers from the PVs. Improved signal detection facilitating a more robust electrical isolation might be associated with a better outcome. This retrospective cohort study compared PVI procedures using a novel high-density mapping system (HDM) with improved signal detection vs. age- and sex-matched PVIs using a conventional 3D mapping system (COM). Endpoints comprised freedom from AF and procedural parameters. In total, 108 patients (mean age 63.9 ± 11.2 years, 56.5% male, 50.9% paroxysmal AF) were included (n = 54 patients/group). Our analysis revealed that HDM was not superior regarding freedom from AF (mean follow-up of 494.7 ± 26.2 days), with one- and two-year AF recurrence rates of 38.9%/46.5% (HDM) and 38.9%/42.2% (COM), respectively. HDM was associated with reduction in fluoroscopy times (18.8 ± 10.6 vs. 29.8 ± 13.4 min; p < 0.01) and total radiation dose (866.0 ± 1003.3 vs. 1731.2 ± 1978.4 cGy; p < 0.01) compared to the COM group. HDM was equivalent but not superior to COM with respect to clinical outcome after PVI and resulted in reduced fluoroscopy time and radiation exposure. These results suggest that HDM-guided PVI is effective and safe for AF ablation. Potential benefits in comparison to conventional mapping systems, e.g. arrhythmia recurrence rates, have to be addressed in randomized trials.

Multiple peritricuspidal reentry tachycardias after cardiac infiltration by leukaemia: a case report.

BackgroundCardiac involvement by malignant lymphocytic neoplasms is a rare phenomenon. Little is known concerning cardiotoxicity in the chronic phase after completion of treatment.Case summaryA 50-year-old woman with a past history of cardiac involvement of acute lymphoblastic leukaemia (ALL) underwent electrophysiologic study and catheter ablation for symptomatic atrial tachycardia (AT). She was diagnosed with ALL when she was 8 years old and treated with systematic chemotherapy with prednisolone and vincristine. After complete remission, she suffered from repeated palpitations beginning at the age of 16 years. Electrophysiologic study using high-density (HD) mapping showed two types of peritricuspid AT in addition to low voltage in the right atrium with conduction delay.DiscussionCardiac involvement by malignant lymphocytic neoplasms is a rare phenomenon, and cardiac infiltration often disappears after remission of ALL. Thus, little is known about cardiac electrophysiological characteristics in the chronic phase of complete remission of ALL. We describe a rare case of a patient with multiple peritricuspidal reentry tachycardias after cardiac infiltration by leukaemia using a HD mapping system.

High-density Mapping Reveals Short-term Reversibility of Atrial Ablation Lesions

Abstract Cardiac arrhythmias such as atrial fibrillation occur frequently in industrialized countries. Radiofrequency ablation (RFA) is a standard treatment if drug therapy fails. This minimally invasive surgery aims at stabilizing the heart rhythm on a permanent basis. However, the procedure commonly needs to be repeated because of the high recurrence rate of arrhythmias. Non-transmural lesions as well as gaps within linear lesions are among the main problems during the RFA. The assessment of lesion formation is not adequate in state of the art procedures. Therefore, the aim of this study is to investigate the short-term reversibility of lesions using human electrograms recorded by a high-density mapping system during an electrophysiological study (EPS). A predefined measurement protocol was executed during the EPS in order to create three ablation points in the left atrium. Subsequently, after preprocessing the recorded signals, electrogram (EGM) paths were formed along the endocardial surface of the atrium. By analyzing changes of peak to peak amplitudes of unipolar EGMs before and after ablation, it was possible to distinguish lesion area and healthy myocardium. The peak to peak amplitudes of the EGMs decreased by 40-61% after 30 seconds of ablation. Furthermore, we analyzed the morphological changes of EGMs surrounding the lesion. High-density mapping data showed that not only the tissue, which had direct contact with the catheter tip during the RFA, but also the surrounding tissue was affected. This was demonstrated by low peak to peak amplitudes in large areas with a width of 14 mm around the center of the ablation lesion. After right pulmonary vein isolation, high-density mapping was repeated on the previous lesions. The outer region of RFA-treated tissue appears to recover as opposed to the central core of the ablation point. This observation suggests that the meaningfulness of an immediate remap after ablation during an EPS may lead the physician to false conclusions

Initial single centre experience with the novel Rhythmia© high density mapping system in an all comer collective of 400 electrophysiological patients

BackgroundA novel, automatically annotating ultra-high density mapping system (Rhythmia©, Boston Scientific) collects a high number and quality of electrograms (EGMs). So far, data on general use in the electrophysiological laboratory are sparse. MethodsWe retrospectively analyzed all our ablations using Rhythmia and recorded patient clinical data, procedural parameters, and mapping parameters including the count of EGMs, mapping time, and mapping volume. Where appropriate, procedural parameters were compared over time to assess a learning curve. Results400 patients underwent ablation of atrial fibrillation (n = 202), typical (n = 16) or atypical atrial flutter (n = 49), VT (n = 48), PVC (n = 35), accessory pathways (n = 14), AVNRT (n = 4), and focal atrial tachycardia (n = 32). System use was feasible, as no procedure had to be stopped for technical reasons and no ablation had to be withheld because of mapping failure, and safe, with an overall complication rate of 2.25%. Initial restrictions in manoeuvrability of the mapping catheter were overcome rapidly, as indicated by a significant decrease of fluoroscopy time (20 vs. 14 min, p = 0.02), use of contrast agent (50 vs. 40 ml; p < 0.01), and (not significant) lower procedure times (194 vs. 170 min; p = 0.12; comparing the first with the last third of patients undergoing pulmonary vein isolation only procedure). Ablation of complex left atrial, focal and ventricular tachycardias benefited from the reliable automatic annotation of a high number of EGMs. ConclusionThe use of the Rhythmia is feasible and safe. Initial restrictions in manoeuvrability of the Orion mapping catheter were overcome rapidly. The procedures that benefit the most from ultra-high density mapping are complex left atrial tachycardias, focal tachycardias, and ventricular tachycardias.

073_16988-H2 Electrogram Signature of Specific Activation Patterns: Analysis of Atrial Arrhythmias at High-Density Endocardial Mapping

The significance of fractionated electrograms is object of debate with multiple mechanisms described. Using Rhythmia™, a high-density mapping system, we sought to investigate the relationship between specific electrophysiological phenomena and EGM characteristics at those sites. 25 consecutive

Electrogram signature of specific activation patterns: Analysis of atrial tachycardias at high-density endocardial mapping

The significance of fractionated electrograms (EGMs) is object of debate, with multiple mechanisms described. Using Rhythmia, a high-density mapping system, we sought to investigate the relationship between specific electrophysiological phenomena and EGM characteristics at those sites. Twenty-five consecutive patients underwent high-density atrial mapping during atrial tachycardias. Bipolar EGMs were recorded with a 64-electrode basket catheter. The following atrial phenomena were identified: slow conduction (SC) areas, lines of block (LB), wavefront collisions (WFC), pivot sites (PS), and gaps. EGMs collected at these predefined areas were analyzed in terms of amplitude, duration, and morphology. Twenty-five atrial maps with 195 sites of interest (1755 EGMs) were object of our analysis. Thirty-five percent were sites of SC: fractionation had low amplitude (0.16 ± 0.07 mV) and long duration (87.8 ± 10.7 ms); wavefront collisions were seen in 38% of sites with EGMs shorter in duration (46.5 ± 4.5 ms) and higher in voltage (0.58 ± 0.13 mV); 17% were lines of block, never responsible for fractionation (0.13 ± 0.05 mV; 122.4 ms ± 24.8 ms); 9% were PS with a high degree of fractionation (0.55 ± 0.15 mV; 85.8 ± 7.9 ms). Two gaps were identified (1%) with a low degree of fractionation. Specific EGM characteristics in atrial tachycardia can be reproducibly linked to electrophysiological mechanisms. High-voltage and short-duration EGMs are associated with collision sites and PS that are unlikely to form critical sites for ablation; long-duration, low-voltage EGMs are associated with SC. However, not all SC regions will lie within the critical circuit and identification by only EGM characteristics cannot guide ablation.

P384Characterization of slow conductions areas in scar-related atrial tachycardia. Insights from high density mapping system

P384Characterization of slow conductions areas in scar-related atrial tachycardia. Insights from high density mapping system

P930Low noise floor assessment in a novel high density mapping system

P930Low noise floor assessment in a novel high density mapping system

P383Characterization of reentrant atrial tachycardia circuits with a high density mapping system

P383Characterization of reentrant atrial tachycardia circuits with a high density mapping system

P1473Long-term efficiency of a novel high density mapping system for ablation of atrial tachycardia

P1473Long-term efficiency of a novel high density mapping system for ablation of atrial tachycardia

Preliminary experience with high-density electroanatomical mapping for ablation of atrial fibrillation – Comparison of mini-basket and novel open irrigated magnetic ablation catheter in consecutive patients

BackgroundRecently, a novel electroanatomic mapping system enabling rapid and automatic acquisition of high-resolution maps has been introduced. Previous reports focused on system use in combination with a mini-basket catheter. However, a novel system-specific, magnet-enabled ablation catheter eliminates the need for the mini-basket catheter and can potentially reduce procedure complexity and cost. Here we present our first experience from two consecutive case series using both procedural settings. MethodsIn 14 consecutive patients (67±9years, 5 male) with paroxysmal (n=10) or persistent AF (n=4) undergoing de-novo (n=8) or repeat (n=6) AF ablation, left atrial electroanatomical maps were acquired with a mini-basket and in 22 patients (64±9years, 17 male) with paroxysmal (n=4) or persistent AF (n=18) undergoing de-novo (n=12) or repeat (n=10) AF ablation with the new ablation catheter. ResultsBoth complete (7.9 [IQR 4.5–16.2] vs 18.8 [IQR 12.0–25.5] minutes, p=0.005) and partial maps (3.0 [IQR 2.0–4.6] vs 4.5 [IQR 2.0–6.0] minutes, p=0.014) acquired with mini-basket required significantly shorter mapping time and had higher point density: 8832±4809 vs 4460±3914 (p=0.014) and 2483±1774 vs 1111±1926 data points (p=0.002) in partial maps.However, procedural (201±52 vs 159±29min, p=0.004) and fluoroscopy time (33±11 vs 25±6min, p=0.005) was significantly higher in the mini-basket group. Procedural endpoints and complications rates were similar in both groups. ConclusionThe high-density mapping system can successfully be used with both mini-basket catheters and ablation catheters employed for electro-anatomic reconstruction of the left atrium. While mapping is faster and point density higher with the mini-basket, procedure and fluoroscopy times are longer. The clinical significance of those findings needs to be investigated in future and larger studies.

Preprocessing of unipolar signals acquired by a novel intracardiac mapping system

Abstract The novel high-density mapping system Rhythmia TM Medical (Boston Scientific, Marlborough, USA) allows a fast and automatic acquisition of intracardiac electrograms (EGMs). For recording the ORION mini-basket catheter is used. Due to the small electrode surface, the spatial averaging is smaller than with other commonly used mapping catheters. This results in a higher quality of unipolar signals. However, these are still corrupted by noise such as high frequency interference. Within this project, methods were developed and benchmarked that can be applied to detect and remove these undesired components. An algorithm was implemented to detect and eliminate artificial peaks in the spectrum of the EGM. The filtered signals showed improved quality in time domain. The performance of the spectral peak detection resulted in a median sensitivity of 92.1% and in a median positive predictive value of 91.9%.

16-22: Quantification of the ablation zone after wide area circumferential pulmonary vein isolation applying a new high-density mapping system

16-22: Quantification of the ablation zone after wide area circumferential pulmonary vein isolation applying a new high-density mapping system

Quantification of spatial inhomogeneity in conduction and initiation of reentrant atrial arrhythmias

In isolated superfused left atria of the rabbit, inhomogeneity in conduction was quantified using the activation times measured with a high-density mapping system. At each recording site, the maximal difference with neighboring activation times (i.e., phase difference) was calculated. Local phase differences were plotted in a phase map, revealing the spatial distribution of inhomogeneities in conduction, and from each map a total index of inhomogeneity was calculated. During slow pacing (2 Hz) local differences in conduction velocity, depending on the direction of propagation, were found already. Inhomogeneity in conduction increased significantly during single early premature beats (inhomogeneity index increased from 2.3 to 3.1; P less than 0.001). The application of multiple premature beats further increased inhomogeneity in conduction, whereas rapid pacing induced the highest level of inhomogeneity (inhomogeneity index 5.3; P less than 0.001). An analysis of the spatial distribution of maximal phase differences revealed that during premature beats inhomogeneities in conduction were limited to an area of 6 mm around the point of origin of the premature impulse, whereas during rapid pacing inhomogeneities in conduction were found throughout the whole preparation. Phase maps constructed during the initiation of reentrant tachyarrhythmias showed that reentry occurred at sites with the highest phase differences. Quantification of spatial inhomogeneities in conduction is a useful tool to evaluate the vulnerability of the myocardial substrate for reentrant arrhythmias.